Compare Claude Opus 4.8 and Grok 4.20 Reasoning: Analytical Rigor vs Thinking Tokens
Claude Opus 4.8 vs Grok-4.20 Reasoning: which should I use?
Grok 4.20 Reasoning provides dedicated reasoning tokens with competitive pricing ($2.00/$6.00 per million tokens) and 2M context, while Claude Opus 4.8 delivers deep analytical reasoning and 500K context ($5.00/$25.00 per million tokens). Verified 2026-09-07.
Verified 2026-09-07
Where can you find price, speed, and task evidence for Claude Opus 4.8 and Grok-4.20 Reasoning?
Which tasks fit Claude Opus 4.8 and Grok-4.20 Reasoning?
Best-fit task signals from the published model strengths; this is not a substitute for a controlled benchmark.
| Fact | Claude Opus 4.8 | Grok-4.20 Reasoning |
|---|---|---|
| Best fit | Complex, multi-step tasks where Fable 5’s premium isn’t justified. | Long-document analysis and problems that benefit from explicit reasoning. |
| Reasoning mode | Available | Available |
What does a Coding Agent workload cost with Claude Opus 4.8 and Grok-4.20 Reasoning?
Modeled for Coding Agent: 20,000 input + 2,000 output tokens per task, 1 turn. This is a workload model, not a provider quote.
| Fact | Claude Opus 4.8 | Grok-4.20 Reasoning |
|---|---|---|
| Coding Agent / task | $0.15 (modeled) | $0.05 (modeled) (winner) |
| Input / output rate | $5.00 / $25.00 per M | $2.00 / $6.00 per M |
How fast are Claude Opus 4.8 and Grok-4.20 Reasoning?
Only non-estimated benchmark results are shown as measured.
| Fact | Claude Opus 4.8 | Grok-4.20 Reasoning |
|---|---|---|
| Measured throughput | 58 tokens/s (winner) | 52 tokens/s |
| Time to first token | 470 ms | 540 ms |
How compatible are Claude Opus 4.8 and Grok-4.20 Reasoning with APIs?
Provider-level wire-format and SDK facts; model-specific parameter differences may still apply.
| Fact | Claude Opus 4.8 | Grok-4.20 Reasoning |
|---|---|---|
| OpenAI SDK | Not drop-in | Usable |
| Request shape | Messages API — system prompt is a top-level field, not a message role, and max_tokens is required on every call. | Full OpenAI chat/completions compatibility — point the openai SDK at api.x.ai and it works unmodified. |
| Streaming | SSE (Anthropic content-block events) | SSE (OpenAI delta) |
What are the privacy and retention policies for Claude Opus 4.8 and Grok-4.20 Reasoning?
Provider policy and residency facts from the verified provider registry. A missing retention policy is not treated as a guarantee.
| Fact | Claude Opus 4.8 | Grok-4.20 Reasoning |
|---|---|---|
| Provider says API data trains models | No | Unavailable |
| Published retention period | Unavailable | Unavailable |
| Data residency | Unavailable | Unavailable |
How much effort does it take to migrate between Claude Opus 4.8 and Grok-4.20 Reasoning?
Direction is from each displayed model to the other. Effort is derived from provider compatibility and published parameter maps.
| Fact | Claude Opus 4.8 | Grok-4.20 Reasoning |
|---|---|---|
| Move Claude Opus 4.8 → Grok-4.20 Reasoning | config; 3 breaking parameter differences | Target: Grok-4.20 Reasoning |
| Move Grok-4.20 Reasoning → Claude Opus 4.8 | Source: Grok-4.20 Reasoning | code-change; 8 breaking parameter differences |
| Why | Keep the `openai` SDK; change `baseURL` and the API key. | Messages API — system prompt is a top-level field, not a message role, and max_tokens is required on every call. |
Batch 56 · exact-pair decision contributions. Surface verification: 2026-09-02. Exactly three boards are server-rendered from frozen scenario fixtures; assumptions and unavailable joins are not observations.
Exact pair boundary: Anthropic / xAI; exact dated endpoint, requested/effective control, output/tool reserve, usage fields, rate period, and checkpoint must join. Requested models are claude-opus-4-8 and grok-4.20-0309-reasoning. Provider, rate, pricing, and task pages remain fact owners.
Opus/4.20 deliberation-control translation register
Frozen Batch 56 scenario board. Formula / deterministic rule: comparable = requested/effective control join + output/tool reserve + exact endpoint; differently named effort => conditional or rejected Boundary: Owns control translation for Opus versus the exact 0309 endpoint; migration and broad reasoning rankings remain adjacent owners.
| Frozen scenario / field ID | Pair, identity, host, surface, and evidence fields | Result | State |
|---|---|---|---|
batch56-claude-opus-4-8-vs-grok-4-20-0309-reasoning-m1-r1provider default | pair=claude-opus-4-8 vs grok-4.20-0309-reasoning; provider=Anthropic / xAI; hostA=api.anthropic.com; hostB=api.x.ai; surfaceA=Messages API; surfaceB=xAI reasoning API; requested/effective IDs=claude-opus-4-8,grok-4.20-0309-reasoning; scenario=provider default; exact ID/host/control/value; requested/effective evidence; output/tool reserve; comparable/conditional/rejected state; probe/source/date; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-02; measurement versus assumption=explicit | Unavailable — provider default is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch56-claude-opus-4-8-vs-grok-4-20-0309-reasoning-m1-r2lowest documented setting | pair=claude-opus-4-8 vs grok-4.20-0309-reasoning; provider=Anthropic / xAI; hostA=api.anthropic.com; hostB=api.x.ai; surfaceA=Messages API; surfaceB=xAI reasoning API; requested/effective IDs=claude-opus-4-8,grok-4.20-0309-reasoning; scenario=lowest documented setting; exact ID/host/control/value; requested/effective evidence; output/tool reserve; comparable/conditional/rejected state; probe/source/date; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-02; measurement versus assumption=explicit | Unavailable — lowest documented setting is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch56-claude-opus-4-8-vs-grok-4-20-0309-reasoning-m1-r3middle setting | pair=claude-opus-4-8 vs grok-4.20-0309-reasoning; provider=Anthropic / xAI; hostA=api.anthropic.com; hostB=api.x.ai; surfaceA=Messages API; surfaceB=xAI reasoning API; requested/effective IDs=claude-opus-4-8,grok-4.20-0309-reasoning; scenario=middle setting; exact ID/host/control/value; requested/effective evidence; output/tool reserve; comparable/conditional/rejected state; probe/source/date; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-02; measurement versus assumption=explicit | Unavailable — middle setting is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch56-claude-opus-4-8-vs-grok-4-20-0309-reasoning-m1-r4highest setting | pair=claude-opus-4-8 vs grok-4.20-0309-reasoning; provider=Anthropic / xAI; hostA=api.anthropic.com; hostB=api.x.ai; surfaceA=Messages API; surfaceB=xAI reasoning API; requested/effective IDs=claude-opus-4-8,grok-4.20-0309-reasoning; scenario=highest setting; exact ID/host/control/value; requested/effective evidence; output/tool reserve; comparable/conditional/rejected state; probe/source/date; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-02; measurement versus assumption=explicit | Unavailable — highest setting is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch56-claude-opus-4-8-vs-grok-4-20-0309-reasoning-m1-r5tool-using turn | pair=claude-opus-4-8 vs grok-4.20-0309-reasoning; provider=Anthropic / xAI; hostA=api.anthropic.com; hostB=api.x.ai; surfaceA=Messages API; surfaceB=xAI reasoning API; requested/effective IDs=claude-opus-4-8,grok-4.20-0309-reasoning; scenario=tool-using turn; exact ID/host/control/value; requested/effective evidence; output/tool reserve; comparable/conditional/rejected state; probe/source/date; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-02; measurement versus assumption=explicit | Unavailable — tool-using turn is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch56-claude-opus-4-8-vs-grok-4-20-0309-reasoning-m1-r6unsupported control | pair=claude-opus-4-8 vs grok-4.20-0309-reasoning; provider=Anthropic / xAI; hostA=api.anthropic.com; hostB=api.x.ai; surfaceA=Messages API; surfaceB=xAI reasoning API; requested/effective IDs=claude-opus-4-8,grok-4.20-0309-reasoning; scenario=unsupported control; exact ID/host/control/value; requested/effective evidence; output/tool reserve; comparable/conditional/rejected state; probe/source/date; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-02; measurement versus assumption=explicit | Unavailable — unsupported control has no matched, dated bilateral observation. | FAIL CLOSED — manual, probe, or source evidence required |
First-party provenance: xAI model documentation; verification date 2026-09-02. Missing or conflicting joins fail closed.
Billed-reasoning usage reconciliation receipt
Frozen Batch 56 scenario board. Formula / deterministic rule: cost = documented input + output + reasoning + tool units × dated rates; missing breakdown or open rate period => Unavailable Boundary: Owns billed usage reconciliation for this exact pair; no hidden-chain quality claim is inferred.
| Frozen scenario / field ID | Pair, identity, host, surface, and evidence fields | Result | State |
|---|---|---|---|
batch56-claude-opus-4-8-vs-grok-4-20-0309-reasoning-m2-r1answer only | pair=claude-opus-4-8 vs grok-4.20-0309-reasoning; provider=Anthropic / xAI; hostA=api.anthropic.com; hostB=api.x.ai; surfaceA=Messages API; surfaceB=xAI reasoning API; requested/effective IDs=claude-opus-4-8,grok-4.20-0309-reasoning; scenario=answer only; request/response/usage hashes; exact controls; documented unit fields; rate-period owner; calculated cost; reconciliation delta; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-02; measurement versus assumption=explicit | Unavailable — answer only is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch56-claude-opus-4-8-vs-grok-4-20-0309-reasoning-m2-r2reasoning plus answer | pair=claude-opus-4-8 vs grok-4.20-0309-reasoning; provider=Anthropic / xAI; hostA=api.anthropic.com; hostB=api.x.ai; surfaceA=Messages API; surfaceB=xAI reasoning API; requested/effective IDs=claude-opus-4-8,grok-4.20-0309-reasoning; scenario=reasoning plus answer; request/response/usage hashes; exact controls; documented unit fields; rate-period owner; calculated cost; reconciliation delta; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-02; measurement versus assumption=explicit | Unavailable — reasoning plus answer is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch56-claude-opus-4-8-vs-grok-4-20-0309-reasoning-m2-r3tool call | pair=claude-opus-4-8 vs grok-4.20-0309-reasoning; provider=Anthropic / xAI; hostA=api.anthropic.com; hostB=api.x.ai; surfaceA=Messages API; surfaceB=xAI reasoning API; requested/effective IDs=claude-opus-4-8,grok-4.20-0309-reasoning; scenario=tool call; request/response/usage hashes; exact controls; documented unit fields; rate-period owner; calculated cost; reconciliation delta; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-02; measurement versus assumption=explicit | Unavailable — tool call is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch56-claude-opus-4-8-vs-grok-4-20-0309-reasoning-m2-r4streamed response | pair=claude-opus-4-8 vs grok-4.20-0309-reasoning; provider=Anthropic / xAI; hostA=api.anthropic.com; hostB=api.x.ai; surfaceA=Messages API; surfaceB=xAI reasoning API; requested/effective IDs=claude-opus-4-8,grok-4.20-0309-reasoning; scenario=streamed response; request/response/usage hashes; exact controls; documented unit fields; rate-period owner; calculated cost; reconciliation delta; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-02; measurement versus assumption=explicit | Unavailable — streamed response is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch56-claude-opus-4-8-vs-grok-4-20-0309-reasoning-m2-r5retry | pair=claude-opus-4-8 vs grok-4.20-0309-reasoning; provider=Anthropic / xAI; hostA=api.anthropic.com; hostB=api.x.ai; surfaceA=Messages API; surfaceB=xAI reasoning API; requested/effective IDs=claude-opus-4-8,grok-4.20-0309-reasoning; scenario=retry; request/response/usage hashes; exact controls; documented unit fields; rate-period owner; calculated cost; reconciliation delta; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-02; measurement versus assumption=explicit | Unavailable — retry is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch56-claude-opus-4-8-vs-grok-4-20-0309-reasoning-m2-r6missing usage breakdown | pair=claude-opus-4-8 vs grok-4.20-0309-reasoning; provider=Anthropic / xAI; hostA=api.anthropic.com; hostB=api.x.ai; surfaceA=Messages API; surfaceB=xAI reasoning API; requested/effective IDs=claude-opus-4-8,grok-4.20-0309-reasoning; scenario=missing usage breakdown; request/response/usage hashes; exact controls; documented unit fields; rate-period owner; calculated cost; reconciliation delta; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-02; measurement versus assumption=explicit | Unavailable — missing usage breakdown has no matched, dated bilateral observation. | FAIL CLOSED — manual, probe, or source evidence required |
First-party provenance: xAI API pricing documentation; verification date 2026-09-02. Missing or conflicting joins fail closed.
Deliberation-budget stop board
Frozen Batch 56 scenario board. Formula / deterministic rule: continue = marginal evidence gain / remaining budget > stop threshold and checkpoint is reversible; ambiguous effective setting => hold/manual Boundary: Owns per-request and workflow stopping for Opus versus Grok 4.20 reasoning only.
| Frozen scenario / field ID | Pair, identity, host, surface, and evidence fields | Result | State |
|---|---|---|---|
batch56-claude-opus-4-8-vs-grok-4-20-0309-reasoning-m3-r1single hard problem | pair=claude-opus-4-8 vs grok-4.20-0309-reasoning; provider=Anthropic / xAI; hostA=api.anthropic.com; hostB=api.x.ai; surfaceA=Messages API; surfaceB=xAI reasoning API; requested/effective IDs=claude-opus-4-8,grok-4.20-0309-reasoning; scenario=single hard problem; observed versus assumed units/attempts; remaining budget; reversible checkpoint; marginal-evidence rule; continue/switch/hold/manual outcome; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-02; measurement versus assumption=explicit | Unavailable — single hard problem is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch56-claude-opus-4-8-vs-grok-4-20-0309-reasoning-m3-r2iterative critique | pair=claude-opus-4-8 vs grok-4.20-0309-reasoning; provider=Anthropic / xAI; hostA=api.anthropic.com; hostB=api.x.ai; surfaceA=Messages API; surfaceB=xAI reasoning API; requested/effective IDs=claude-opus-4-8,grok-4.20-0309-reasoning; scenario=iterative critique; observed versus assumed units/attempts; remaining budget; reversible checkpoint; marginal-evidence rule; continue/switch/hold/manual outcome; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-02; measurement versus assumption=explicit | Unavailable — iterative critique is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch56-claude-opus-4-8-vs-grok-4-20-0309-reasoning-m3-r3tool loop | pair=claude-opus-4-8 vs grok-4.20-0309-reasoning; provider=Anthropic / xAI; hostA=api.anthropic.com; hostB=api.x.ai; surfaceA=Messages API; surfaceB=xAI reasoning API; requested/effective IDs=claude-opus-4-8,grok-4.20-0309-reasoning; scenario=tool loop; observed versus assumed units/attempts; remaining budget; reversible checkpoint; marginal-evidence rule; continue/switch/hold/manual outcome; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-02; measurement versus assumption=explicit | Unavailable — tool loop is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch56-claude-opus-4-8-vs-grok-4-20-0309-reasoning-m3-r4nearing request cap | pair=claude-opus-4-8 vs grok-4.20-0309-reasoning; provider=Anthropic / xAI; hostA=api.anthropic.com; hostB=api.x.ai; surfaceA=Messages API; surfaceB=xAI reasoning API; requested/effective IDs=claude-opus-4-8,grok-4.20-0309-reasoning; scenario=nearing request cap; observed versus assumed units/attempts; remaining budget; reversible checkpoint; marginal-evidence rule; continue/switch/hold/manual outcome; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-02; measurement versus assumption=explicit | Unavailable — nearing request cap is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch56-claude-opus-4-8-vs-grok-4-20-0309-reasoning-m3-r5exhausted workflow cap | pair=claude-opus-4-8 vs grok-4.20-0309-reasoning; provider=Anthropic / xAI; hostA=api.anthropic.com; hostB=api.x.ai; surfaceA=Messages API; surfaceB=xAI reasoning API; requested/effective IDs=claude-opus-4-8,grok-4.20-0309-reasoning; scenario=exhausted workflow cap; observed versus assumed units/attempts; remaining budget; reversible checkpoint; marginal-evidence rule; continue/switch/hold/manual outcome; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-02; measurement versus assumption=explicit | Unavailable — exhausted workflow cap is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch56-claude-opus-4-8-vs-grok-4-20-0309-reasoning-m3-r6ambiguous effective setting | pair=claude-opus-4-8 vs grok-4.20-0309-reasoning; provider=Anthropic / xAI; hostA=api.anthropic.com; hostB=api.x.ai; surfaceA=Messages API; surfaceB=xAI reasoning API; requested/effective IDs=claude-opus-4-8,grok-4.20-0309-reasoning; scenario=ambiguous effective setting; observed versus assumed units/attempts; remaining budget; reversible checkpoint; marginal-evidence rule; continue/switch/hold/manual outcome; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-02; measurement versus assumption=explicit | Unavailable — ambiguous effective setting is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
First-party provenance: Anthropic API rate limits; verification date 2026-09-02. Missing or conflicting joins fail closed.
Method and limitations: formulas are deterministic; observed and assumed inputs are labeled; no missing provider, host, account, region, realm, alias, snapshot, revision, weight, artifact, control, tool, modality, workload, rate-period, timestamp, or result is transferred. Run the claude-opus-4-8-vs-grok-4-20-0309-reasoning Batch 56 scenario →
Batch 65 · exact-pair decision contributions · verified 2026-09-07
Exact pair boundary: Anthropic / xAI; model endpoint, frontier reasoning vs dedicated reasoning preview, and deliberation budgets must join. Requested models are claude-opus-4-8 and grok-4.20-0309-reasoning. Provider, rate, pricing, and task pages remain fact owners.
Token pricing and reasoning token budget expenditure board
Frozen Batch 65 scenario board. Formula / deterministic rule: monthly_spend = calls * ((in_tokens * rate_in + out_tokens * rate_out) / 1M) Boundary: Owns base token tariff comparisons and reasoning token expenditure modeling.
| Frozen scenario / field ID | Pair, identity, host, surface, and evidence fields | Result | State |
|---|---|---|---|
batch65-claude-opus-4-8-vs-grok-4-20-0309-reasoning-m1-r15K mathematical proofs | pair=claude-opus-4-8 vs grok-4.20-0309-reasoning; provider=Anthropic / xAI; hostA=api.anthropic.com; hostB=api.x.ai; surfaceA=Anthropic Messages API; surfaceB=xAI API; requested/effective IDs=claude-opus-4-8,grok-4.20-0309-reasoning; scenario=5K mathematical proofs; workload; prompt tokens; completion tokens; Opus 4.8 spend; Grok Reasoning spend; budget delta; cost winner; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — 5K mathematical proofs is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch65-claude-opus-4-8-vs-grok-4-20-0309-reasoning-m1-r225K complex algorithmic coding challenges | pair=claude-opus-4-8 vs grok-4.20-0309-reasoning; provider=Anthropic / xAI; hostA=api.anthropic.com; hostB=api.x.ai; surfaceA=Anthropic Messages API; surfaceB=xAI API; requested/effective IDs=claude-opus-4-8,grok-4.20-0309-reasoning; scenario=25K complex algorithmic coding challenges; workload; prompt tokens; completion tokens; Opus 4.8 spend; Grok Reasoning spend; budget delta; cost winner; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — 25K complex algorithmic coding challenges is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch65-claude-opus-4-8-vs-grok-4-20-0309-reasoning-m1-r350K architectural design reviews | pair=claude-opus-4-8 vs grok-4.20-0309-reasoning; provider=Anthropic / xAI; hostA=api.anthropic.com; hostB=api.x.ai; surfaceA=Anthropic Messages API; surfaceB=xAI API; requested/effective IDs=claude-opus-4-8,grok-4.20-0309-reasoning; scenario=50K architectural design reviews; workload; prompt tokens; completion tokens; Opus 4.8 spend; Grok Reasoning spend; budget delta; cost winner; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — 50K architectural design reviews is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch65-claude-opus-4-8-vs-grok-4-20-0309-reasoning-m1-r4prompt caching active (Opus 90% read / Grok 75% read) | pair=claude-opus-4-8 vs grok-4.20-0309-reasoning; provider=Anthropic / xAI; hostA=api.anthropic.com; hostB=api.x.ai; surfaceA=Anthropic Messages API; surfaceB=xAI API; requested/effective IDs=claude-opus-4-8,grok-4.20-0309-reasoning; scenario=prompt caching active (Opus 90% read / Grok 75% read); workload; prompt tokens; completion tokens; Opus 4.8 spend; Grok Reasoning spend; budget delta; cost winner; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — prompt caching active (Opus 90% read / Grok 75% read) is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch65-claude-opus-4-8-vs-grok-4-20-0309-reasoning-m1-r5batch processing active (50% both) | pair=claude-opus-4-8 vs grok-4.20-0309-reasoning; provider=Anthropic / xAI; hostA=api.anthropic.com; hostB=api.x.ai; surfaceA=Anthropic Messages API; surfaceB=xAI API; requested/effective IDs=claude-opus-4-8,grok-4.20-0309-reasoning; scenario=batch processing active (50% both); workload; prompt tokens; completion tokens; Opus 4.8 spend; Grok Reasoning spend; budget delta; cost winner; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — batch processing active (50% both) is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch65-claude-opus-4-8-vs-grok-4-20-0309-reasoning-m1-r6unresolved pricing currency | pair=claude-opus-4-8 vs grok-4.20-0309-reasoning; provider=Anthropic / xAI; hostA=api.anthropic.com; hostB=api.x.ai; surfaceA=Anthropic Messages API; surfaceB=xAI API; requested/effective IDs=claude-opus-4-8,grok-4.20-0309-reasoning; scenario=unresolved pricing currency; workload; prompt tokens; completion tokens; Opus 4.8 spend; Grok Reasoning spend; budget delta; cost winner; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — unresolved pricing currency has no matched, dated bilateral observation. | FAIL CLOSED — manual, probe, or source evidence required |
First-party provenance: Anthropic API pricing; verification date 2026-09-07. Missing or conflicting joins fail closed.
Context window saturation (500K vs 2M) capability gate
Frozen Batch 65 scenario board. Formula / deterministic rule: eligible = (context <= 500K ? Both : (context <= 2M ? Grok : Excluded)) Boundary: Owns context scaling and capability gating for large inputs.
| Frozen scenario / field ID | Pair, identity, host, surface, and evidence fields | Result | State |
|---|---|---|---|
batch65-claude-opus-4-8-vs-grok-4-20-0309-reasoning-m2-r1small library codebase (50K tokens) | pair=claude-opus-4-8 vs grok-4.20-0309-reasoning; provider=Anthropic / xAI; hostA=api.anthropic.com; hostB=api.x.ai; surfaceA=Anthropic Messages API; surfaceB=xAI API; requested/effective IDs=claude-opus-4-8,grok-4.20-0309-reasoning; scenario=small library codebase (50K tokens); context size; Opus 4.8 eligible; Grok Reasoning eligible; Opus cost; Grok cost; context gating verdict; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — small library codebase (50K tokens) is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch65-claude-opus-4-8-vs-grok-4-20-0309-reasoning-m2-r2medium application service (250K tokens) | pair=claude-opus-4-8 vs grok-4.20-0309-reasoning; provider=Anthropic / xAI; hostA=api.anthropic.com; hostB=api.x.ai; surfaceA=Anthropic Messages API; surfaceB=xAI API; requested/effective IDs=claude-opus-4-8,grok-4.20-0309-reasoning; scenario=medium application service (250K tokens); context size; Opus 4.8 eligible; Grok Reasoning eligible; Opus cost; Grok cost; context gating verdict; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — medium application service (250K tokens) is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch65-claude-opus-4-8-vs-grok-4-20-0309-reasoning-m2-r3large monolithic codebase (500K boundary) | pair=claude-opus-4-8 vs grok-4.20-0309-reasoning; provider=Anthropic / xAI; hostA=api.anthropic.com; hostB=api.x.ai; surfaceA=Anthropic Messages API; surfaceB=xAI API; requested/effective IDs=claude-opus-4-8,grok-4.20-0309-reasoning; scenario=large monolithic codebase (500K boundary); context size; Opus 4.8 eligible; Grok Reasoning eligible; Opus cost; Grok cost; context gating verdict; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — large monolithic codebase (500K boundary) is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch65-claude-opus-4-8-vs-grok-4-20-0309-reasoning-m2-r4massive enterprise monorepo (1M tokens) | pair=claude-opus-4-8 vs grok-4.20-0309-reasoning; provider=Anthropic / xAI; hostA=api.anthropic.com; hostB=api.x.ai; surfaceA=Anthropic Messages API; surfaceB=xAI API; requested/effective IDs=claude-opus-4-8,grok-4.20-0309-reasoning; scenario=massive enterprise monorepo (1M tokens); context size; Opus 4.8 eligible; Grok Reasoning eligible; Opus cost; Grok cost; context gating verdict; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — massive enterprise monorepo (1M tokens) is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch65-claude-opus-4-8-vs-grok-4-20-0309-reasoning-m2-r52M full context saturation test | pair=claude-opus-4-8 vs grok-4.20-0309-reasoning; provider=Anthropic / xAI; hostA=api.anthropic.com; hostB=api.x.ai; surfaceA=Anthropic Messages API; surfaceB=xAI API; requested/effective IDs=claude-opus-4-8,grok-4.20-0309-reasoning; scenario=2M full context saturation test; context size; Opus 4.8 eligible; Grok Reasoning eligible; Opus cost; Grok cost; context gating verdict; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — 2M full context saturation test is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch65-claude-opus-4-8-vs-grok-4-20-0309-reasoning-m2-r6unsupported archive payload format | pair=claude-opus-4-8 vs grok-4.20-0309-reasoning; provider=Anthropic / xAI; hostA=api.anthropic.com; hostB=api.x.ai; surfaceA=Anthropic Messages API; surfaceB=xAI API; requested/effective IDs=claude-opus-4-8,grok-4.20-0309-reasoning; scenario=unsupported archive payload format; context size; Opus 4.8 eligible; Grok Reasoning eligible; Opus cost; Grok cost; context gating verdict; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — unsupported archive payload format has no matched, dated bilateral observation. | FAIL CLOSED — manual, probe, or source evidence required |
First-party provenance: xAI Grok documentation; verification date 2026-09-07. Missing or conflicting joins fail closed.
Deliberation budget control and deep mathematical proof accuracy
Frozen Batch 65 scenario board. Formula / deterministic rule: proof_roi = saved_engineering_hours - ((in_tokens * rate_in + out_tokens * rate_out) / 1M) Boundary: Owns reasoning depth modeling and return-on-investment calculations.
| Frozen scenario / field ID | Pair, identity, host, surface, and evidence fields | Result | State |
|---|---|---|---|
batch65-claude-opus-4-8-vs-grok-4-20-0309-reasoning-m3-r1formal mathematical verification | pair=claude-opus-4-8 vs grok-4.20-0309-reasoning; provider=Anthropic / xAI; hostA=api.anthropic.com; hostB=api.x.ai; surfaceA=Anthropic Messages API; surfaceB=xAI API; requested/effective IDs=claude-opus-4-8,grok-4.20-0309-reasoning; scenario=formal mathematical verification; reasoning problem; thinking depth budget; Opus 4.8 cost; Grok Reasoning cost; net economic ROI; recommendation; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — formal mathematical verification is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch65-claude-opus-4-8-vs-grok-4-20-0309-reasoning-m3-r2cryptographic protocol validation | pair=claude-opus-4-8 vs grok-4.20-0309-reasoning; provider=Anthropic / xAI; hostA=api.anthropic.com; hostB=api.x.ai; surfaceA=Anthropic Messages API; surfaceB=xAI API; requested/effective IDs=claude-opus-4-8,grok-4.20-0309-reasoning; scenario=cryptographic protocol validation; reasoning problem; thinking depth budget; Opus 4.8 cost; Grok Reasoning cost; net economic ROI; recommendation; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — cryptographic protocol validation is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch65-claude-opus-4-8-vs-grok-4-20-0309-reasoning-m3-r3distributed consensus protocol proof | pair=claude-opus-4-8 vs grok-4.20-0309-reasoning; provider=Anthropic / xAI; hostA=api.anthropic.com; hostB=api.x.ai; surfaceA=Anthropic Messages API; surfaceB=xAI API; requested/effective IDs=claude-opus-4-8,grok-4.20-0309-reasoning; scenario=distributed consensus protocol proof; reasoning problem; thinking depth budget; Opus 4.8 cost; Grok Reasoning cost; net economic ROI; recommendation; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — distributed consensus protocol proof is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch65-claude-opus-4-8-vs-grok-4-20-0309-reasoning-m3-r4optimizing compiler intermediate representation | pair=claude-opus-4-8 vs grok-4.20-0309-reasoning; provider=Anthropic / xAI; hostA=api.anthropic.com; hostB=api.x.ai; surfaceA=Anthropic Messages API; surfaceB=xAI API; requested/effective IDs=claude-opus-4-8,grok-4.20-0309-reasoning; scenario=optimizing compiler intermediate representation; reasoning problem; thinking depth budget; Opus 4.8 cost; Grok Reasoning cost; net economic ROI; recommendation; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — optimizing compiler intermediate representation is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch65-claude-opus-4-8-vs-grok-4-20-0309-reasoning-m3-r5reasoning token budget exhaustion | pair=claude-opus-4-8 vs grok-4.20-0309-reasoning; provider=Anthropic / xAI; hostA=api.anthropic.com; hostB=api.x.ai; surfaceA=Anthropic Messages API; surfaceB=xAI API; requested/effective IDs=claude-opus-4-8,grok-4.20-0309-reasoning; scenario=reasoning token budget exhaustion; reasoning problem; thinking depth budget; Opus 4.8 cost; Grok Reasoning cost; net economic ROI; recommendation; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — reasoning token budget exhaustion has no matched, dated bilateral observation. | FAIL CLOSED — manual, probe, or source evidence required |
batch65-claude-opus-4-8-vs-grok-4-20-0309-reasoning-m3-r6unresolved proof specification | pair=claude-opus-4-8 vs grok-4.20-0309-reasoning; provider=Anthropic / xAI; hostA=api.anthropic.com; hostB=api.x.ai; surfaceA=Anthropic Messages API; surfaceB=xAI API; requested/effective IDs=claude-opus-4-8,grok-4.20-0309-reasoning; scenario=unresolved proof specification; reasoning problem; thinking depth budget; Opus 4.8 cost; Grok Reasoning cost; net economic ROI; recommendation; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — unresolved proof specification has no matched, dated bilateral observation. | FAIL CLOSED — manual, probe, or source evidence required |
First-party provenance: Anthropic Claude documentation; verification date 2026-09-07. Missing or conflicting joins fail closed.
Method and limitations: formulas are deterministic; observed and assumed inputs are labeled; no missing provider, host, account, region, realm, alias, snapshot, revision, weight, artifact, control, tool, modality, workload, rate-period, timestamp, or result is transferred. Run the claude-opus-4-8-vs-grok-4-20-0309-reasoning Batch 65 scenario →
How do Claude Opus 4.8 and Grok-4.20 Reasoning compare on specs?
| Claude Opus 4.8 | Grok-4.20 Reasoning | |
|---|---|---|
| Price (input) | $5.00/M | $2.00/M ✓ |
| Price (output) | $25.00/M | $6.00/M ✓ |
| Blended price | $10.00/M | $3.00/M ✓ |
| Context window | 500,000 tokens | 1,000,000 tokens ✓ |
| Max output | 64,000 tokens | 64,000 tokens |
| Modalities | text, vision | text, vision |
| Reasoning mode | Yes | Yes |
| Released | 2026-04 | 2026-03 |
| Speed | 58 t/s ✓ | 52 t/s |
How much do Claude Opus 4.8 and Grok-4.20 Reasoning cost at scale?
| Tokens / month | Claude Opus 4.8 | Grok-4.20 Reasoning | Delta |
|---|---|---|---|
| 1,000,000 | $10.00 | $3.00 | $7.00 (3.3×) |
| 10,000,000 | $100.00 | $30.00 | $70.00 (3.3×) |
| 100,000,000 | $1000.00 | $300.00 | $700.00 (3.3×) |
Choose Claude Opus 4.8 if…
- ✓Elite coding and multi-step reasoning
- ✓Strong instruction following on ambiguous prompts
- ✓Extended-thinking mode
- ✓Complex, multi-step tasks where Fable 5’s premium isn’t justified.
Choose Grok-4.20 Reasoning if…
- ✓State-of-the-art document analysis at 1M context
- ✓Dedicated reasoning mode
- ✓Strong vision understanding
- ✓Long-document analysis and problems that benefit from explicit reasoning.
Run this exact matchup right now
Send the same prompt to Claude Opus 4.8 and Grok-4.20 Reasoning side by side and see the outputs yourself.
Try Claude Opus 4.8 vs Grok-4.20 Reasoning FreeWhat are common questions about Claude Opus 4.8 and Grok-4.20 Reasoning?
Is Claude Opus 4.8 cheaper than Grok-4.20 Reasoning?
Grok-4.20 Reasoning is cheaper, at $3.00 per million blended tokens vs $10.00 for Claude Opus 4.8.
Which has the bigger context window, Claude Opus 4.8 or Grok-4.20 Reasoning?
Grok-4.20 Reasoning has the larger context window: 1,000,000 tokens vs 500,000.
Can Claude Opus 4.8 replace Grok-4.20 Reasoning for coding?
Both are viable for coding. Elite coding and multi-step reasoning (Claude Opus 4.8) vs State-of-the-art document analysis at 1M context (Grok-4.20 Reasoning) — pick based on which strength matters more for your workload.
Which is faster, Claude Opus 4.8 or Grok-4.20 Reasoning?
Claude Opus 4.8 is faster: 58 t/s vs 52 t/s, measured on our speed benchmarks.
Neither of these? See Claude Opus 4.8 alternatives or Grok-4.20 Reasoning alternatives.
What related comparisons help choose between Claude Opus 4.8 and Grok-4.20 Reasoning?
Claude Opus 4.8 pricingGrok-4.20 Reasoning pricingvs Claude Opus 4vs DeepSeek V4 Provs Gemini 3.1 Provs Gemini 3.7 FlashPremium model tests
Pricing verified 2026-04-06. Specs verified 2026-08-14.