Compare Claude Opus 4.8 and GPT-5.6 Luna: Frontier Rigor vs Lightweight Execution
Claude Opus 4.8 vs GPT-5.6 Luna: which should I use?
OpenAI GPT-5.6 Luna offers high-throughput execution ($1.00/$6.00 per million tokens) with 1M context, while Anthropic Claude Opus 4.8 provides deep extended thinking 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 GPT-5.6 Luna?
Which tasks fit Claude Opus 4.8 and GPT-5.6 Luna?
Best-fit task signals from the published model strengths; this is not a substitute for a controlled benchmark.
| Fact | Claude Opus 4.8 | GPT-5.6 Luna |
|---|---|---|
| Best fit | Complex, multi-step tasks where Fable 5’s premium isn’t justified. | High-volume, latency-sensitive tasks like classification, extraction, and chat. |
| Reasoning mode | Available | Unavailable |
What does a Coding Agent workload cost with Claude Opus 4.8 and GPT-5.6 Luna?
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 | GPT-5.6 Luna |
|---|---|---|
| Coding Agent / task | $0.15 (modeled) | $0.03 (modeled) (winner) |
| Input / output rate | $5.00 / $25.00 per M | $1.00 / $6.00 per M |
How fast are Claude Opus 4.8 and GPT-5.6 Luna?
Only non-estimated benchmark results are shown as measured.
| Fact | Claude Opus 4.8 | GPT-5.6 Luna |
|---|---|---|
| Measured throughput | 58 tokens/s | 126 tokens/s (winner) |
| Time to first token | 470 ms | 300 ms |
How compatible are Claude Opus 4.8 and GPT-5.6 Luna with APIs?
Provider-level wire-format and SDK facts; model-specific parameter differences may still apply.
| Fact | Claude Opus 4.8 | GPT-5.6 Luna |
|---|---|---|
| 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. | Canonical /chat/completions and /responses shape — every OpenAI-compatible provider on this site imitates it. |
| Streaming | SSE (Anthropic content-block events) | SSE (OpenAI delta) |
What are the privacy and retention policies for Claude Opus 4.8 and GPT-5.6 Luna?
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 | GPT-5.6 Luna |
|---|---|---|
| Provider says API data trains models | No | No |
| Published retention period | Unavailable | Unavailable |
| Data residency | Unavailable | US by default; EU data residency available on enterprise agreements |
How much effort does it take to migrate between Claude Opus 4.8 and GPT-5.6 Luna?
Direction is from each displayed model to the other. Effort is derived from provider compatibility and published parameter maps.
| Fact | Claude Opus 4.8 | GPT-5.6 Luna |
|---|---|---|
| Move Claude Opus 4.8 → GPT-5.6 Luna | config; 3 breaking parameter differences | Target: GPT-5.6 Luna |
| Move GPT-5.6 Luna → Claude Opus 4.8 | Source: GPT-5.6 Luna | 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 / OpenAI; exact endpoint, effort, tools, schema, raw artifacts, reviewer order, and risk class must join. Requested models are claude-opus-4-8 and gpt-5.6-luna. Provider, rate, pricing, and task pages remain fact owners.
Asymmetric draft-and-review eligibility register
Frozen Batch 56 scenario board. Formula / deterministic rule: eligible = reversibility + harm class + tools/schema + Luna draft controls + independent Opus reviewer + human role; unresolved class => hold Boundary: Owns combined Luna-draft and Opus-review eligibility, not standalone substitution or price leadership.
| Frozen scenario / field ID | Pair, identity, host, surface, and evidence fields | Result | State |
|---|---|---|---|
batch56-claude-opus-4-8-vs-gpt-5-6-luna-m1-r1routine extraction | pair=claude-opus-4-8 vs gpt-5.6-luna; provider=Anthropic / OpenAI; hostA=api.anthropic.com; hostB=api.openai.com; surfaceA=Messages API; surfaceB=Responses API; requested/effective IDs=claude-opus-4-8,gpt-5.6-luna; scenario=routine extraction; harm/reversibility class; required tools/schema; Luna eligibility; Opus independence; mandatory human role; route/hold/block state; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-02; measurement versus assumption=explicit | Unavailable — routine extraction is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch56-claude-opus-4-8-vs-gpt-5-6-luna-m1-r2reversible code suggestion | pair=claude-opus-4-8 vs gpt-5.6-luna; provider=Anthropic / OpenAI; hostA=api.anthropic.com; hostB=api.openai.com; surfaceA=Messages API; surfaceB=Responses API; requested/effective IDs=claude-opus-4-8,gpt-5.6-luna; scenario=reversible code suggestion; harm/reversibility class; required tools/schema; Luna eligibility; Opus independence; mandatory human role; route/hold/block state; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-02; measurement versus assumption=explicit | Unavailable — reversible code suggestion is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch56-claude-opus-4-8-vs-gpt-5-6-luna-m1-r3customer-facing draft | pair=claude-opus-4-8 vs gpt-5.6-luna; provider=Anthropic / OpenAI; hostA=api.anthropic.com; hostB=api.openai.com; surfaceA=Messages API; surfaceB=Responses API; requested/effective IDs=claude-opus-4-8,gpt-5.6-luna; scenario=customer-facing draft; harm/reversibility class; required tools/schema; Luna eligibility; Opus independence; mandatory human role; route/hold/block state; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-02; measurement versus assumption=explicit | Unavailable — customer-facing draft is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch56-claude-opus-4-8-vs-gpt-5-6-luna-m1-r4financial recommendation | pair=claude-opus-4-8 vs gpt-5.6-luna; provider=Anthropic / OpenAI; hostA=api.anthropic.com; hostB=api.openai.com; surfaceA=Messages API; surfaceB=Responses API; requested/effective IDs=claude-opus-4-8,gpt-5.6-luna; scenario=financial recommendation; harm/reversibility class; required tools/schema; Luna eligibility; Opus independence; mandatory human role; route/hold/block state; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-02; measurement versus assumption=explicit | Unavailable — financial recommendation is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch56-claude-opus-4-8-vs-gpt-5-6-luna-m1-r5irreversible action | pair=claude-opus-4-8 vs gpt-5.6-luna; provider=Anthropic / OpenAI; hostA=api.anthropic.com; hostB=api.openai.com; surfaceA=Messages API; surfaceB=Responses API; requested/effective IDs=claude-opus-4-8,gpt-5.6-luna; scenario=irreversible action; harm/reversibility class; required tools/schema; Luna eligibility; Opus independence; mandatory human role; route/hold/block state; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-02; measurement versus assumption=explicit | Unavailable — irreversible action has no matched, dated bilateral observation. | FAIL CLOSED — manual, probe, or source evidence required |
batch56-claude-opus-4-8-vs-gpt-5-6-luna-m1-r6unresolved model ID | pair=claude-opus-4-8 vs gpt-5.6-luna; provider=Anthropic / OpenAI; hostA=api.anthropic.com; hostB=api.openai.com; surfaceA=Messages API; surfaceB=Responses API; requested/effective IDs=claude-opus-4-8,gpt-5.6-luna; scenario=unresolved model ID; harm/reversibility class; required tools/schema; Luna eligibility; Opus independence; mandatory human role; route/hold/block state; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-02; measurement versus assumption=explicit | Unavailable — unresolved model ID has no matched, dated bilateral observation. | FAIL CLOSED — manual, probe, or source evidence required |
First-party provenance: OpenAI Responses API; verification date 2026-09-02. Missing or conflicting joins fail closed.
Independent-error correction receipt
Frozen Batch 56 scenario board. Formula / deterministic rule: correction = corrected Opus-confirmed errors / blinded reviewed drafts; uncontrolled prompts or absent raw artifact => no independence claim Boundary: Owns independent-error evidence for this asymmetric pair; it does not make Opus a universal judge.
| Frozen scenario / field ID | Pair, identity, host, surface, and evidence fields | Result | State |
|---|---|---|---|
batch56-claude-opus-4-8-vs-gpt-5-6-luna-m2-r1clean Luna draft | pair=claude-opus-4-8 vs gpt-5.6-luna; provider=Anthropic / OpenAI; hostA=api.anthropic.com; hostB=api.openai.com; surfaceA=Messages API; surfaceB=Responses API; requested/effective IDs=claude-opus-4-8,gpt-5.6-luna; scenario=clean Luna draft; prompt/draft/review/final hashes; exact IDs/settings; blinded order; validator or human denominator; error class; corrected/uncorrected/Untested result; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-02; measurement versus assumption=explicit | Unavailable — clean Luna draft is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch56-claude-opus-4-8-vs-gpt-5-6-luna-m2-r2Opus-confirmed error | pair=claude-opus-4-8 vs gpt-5.6-luna; provider=Anthropic / OpenAI; hostA=api.anthropic.com; hostB=api.openai.com; surfaceA=Messages API; surfaceB=Responses API; requested/effective IDs=claude-opus-4-8,gpt-5.6-luna; scenario=Opus-confirmed error; prompt/draft/review/final hashes; exact IDs/settings; blinded order; validator or human denominator; error class; corrected/uncorrected/Untested result; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-02; measurement versus assumption=explicit | Unavailable — Opus-confirmed error is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch56-claude-opus-4-8-vs-gpt-5-6-luna-m2-r3Opus false alarm | pair=claude-opus-4-8 vs gpt-5.6-luna; provider=Anthropic / OpenAI; hostA=api.anthropic.com; hostB=api.openai.com; surfaceA=Messages API; surfaceB=Responses API; requested/effective IDs=claude-opus-4-8,gpt-5.6-luna; scenario=Opus false alarm; prompt/draft/review/final hashes; exact IDs/settings; blinded order; validator or human denominator; error class; corrected/uncorrected/Untested result; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-02; measurement versus assumption=explicit | Unavailable — Opus false alarm is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch56-claude-opus-4-8-vs-gpt-5-6-luna-m2-r4shared unsupported claim | pair=claude-opus-4-8 vs gpt-5.6-luna; provider=Anthropic / OpenAI; hostA=api.anthropic.com; hostB=api.openai.com; surfaceA=Messages API; surfaceB=Responses API; requested/effective IDs=claude-opus-4-8,gpt-5.6-luna; scenario=shared unsupported claim; prompt/draft/review/final hashes; exact IDs/settings; blinded order; validator or human denominator; error class; corrected/uncorrected/Untested result; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-02; measurement versus assumption=explicit | Unavailable — shared unsupported claim has no matched, dated bilateral observation. | FAIL CLOSED — manual, probe, or source evidence required |
batch56-claude-opus-4-8-vs-gpt-5-6-luna-m2-r5reviewer disagreement | pair=claude-opus-4-8 vs gpt-5.6-luna; provider=Anthropic / OpenAI; hostA=api.anthropic.com; hostB=api.openai.com; surfaceA=Messages API; surfaceB=Responses API; requested/effective IDs=claude-opus-4-8,gpt-5.6-luna; scenario=reviewer disagreement; prompt/draft/review/final hashes; exact IDs/settings; blinded order; validator or human denominator; error class; corrected/uncorrected/Untested result; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-02; measurement versus assumption=explicit | Unavailable — reviewer disagreement is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch56-claude-opus-4-8-vs-gpt-5-6-luna-m2-r6missing raw artifact | pair=claude-opus-4-8 vs gpt-5.6-luna; provider=Anthropic / OpenAI; hostA=api.anthropic.com; hostB=api.openai.com; surfaceA=Messages API; surfaceB=Responses API; requested/effective IDs=claude-opus-4-8,gpt-5.6-luna; scenario=missing raw artifact; prompt/draft/review/final hashes; exact IDs/settings; blinded order; validator or human denominator; error class; corrected/uncorrected/Untested result; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-02; measurement versus assumption=explicit | Unavailable — missing raw artifact has no matched, dated bilateral observation. | FAIL CLOSED — manual, probe, or source evidence required |
First-party provenance: Anthropic Messages API; verification date 2026-09-02. Missing or conflicting joins fail closed.
Risk-weighted review-coverage allocator
Frozen Batch 56 scenario board. Formula / deterministic rule: covered_loss = Σ(stratum traffic × defect assumption × harm weight × review coverage); missing rate owner or capacity => Unavailable Boundary: Owns coverage allocation under risk and capacity for Luna-first workflows only.
| Frozen scenario / field ID | Pair, identity, host, surface, and evidence fields | Result | State |
|---|---|---|---|
batch56-claude-opus-4-8-vs-gpt-5-6-luna-m3-r10% review | pair=claude-opus-4-8 vs gpt-5.6-luna; provider=Anthropic / OpenAI; hostA=api.anthropic.com; hostB=api.openai.com; surfaceA=Messages API; surfaceB=Responses API; requested/effective IDs=claude-opus-4-8,gpt-5.6-luna; scenario=0% review; traffic/risk strata; observed versus assumed defects; review capacity; dated rate-owner links; covered loss and cost; coverage decision; human fallback; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-02; measurement versus assumption=explicit | Unavailable — 0% review is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch56-claude-opus-4-8-vs-gpt-5-6-luna-m3-r25% review | pair=claude-opus-4-8 vs gpt-5.6-luna; provider=Anthropic / OpenAI; hostA=api.anthropic.com; hostB=api.openai.com; surfaceA=Messages API; surfaceB=Responses API; requested/effective IDs=claude-opus-4-8,gpt-5.6-luna; scenario=5% review; traffic/risk strata; observed versus assumed defects; review capacity; dated rate-owner links; covered loss and cost; coverage decision; human fallback; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-02; measurement versus assumption=explicit | Unavailable — 5% review is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch56-claude-opus-4-8-vs-gpt-5-6-luna-m3-r325% review | pair=claude-opus-4-8 vs gpt-5.6-luna; provider=Anthropic / OpenAI; hostA=api.anthropic.com; hostB=api.openai.com; surfaceA=Messages API; surfaceB=Responses API; requested/effective IDs=claude-opus-4-8,gpt-5.6-luna; scenario=25% review; traffic/risk strata; observed versus assumed defects; review capacity; dated rate-owner links; covered loss and cost; coverage decision; human fallback; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-02; measurement versus assumption=explicit | Unavailable — 25% review is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch56-claude-opus-4-8-vs-gpt-5-6-luna-m3-r4100% review | pair=claude-opus-4-8 vs gpt-5.6-luna; provider=Anthropic / OpenAI; hostA=api.anthropic.com; hostB=api.openai.com; surfaceA=Messages API; surfaceB=Responses API; requested/effective IDs=claude-opus-4-8,gpt-5.6-luna; scenario=100% review; traffic/risk strata; observed versus assumed defects; review capacity; dated rate-owner links; covered loss and cost; coverage decision; human fallback; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-02; measurement versus assumption=explicit | Unavailable — 100% review is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch56-claude-opus-4-8-vs-gpt-5-6-luna-m3-r5disagreement-triggered | pair=claude-opus-4-8 vs gpt-5.6-luna; provider=Anthropic / OpenAI; hostA=api.anthropic.com; hostB=api.openai.com; surfaceA=Messages API; surfaceB=Responses API; requested/effective IDs=claude-opus-4-8,gpt-5.6-luna; scenario=disagreement-triggered; traffic/risk strata; observed versus assumed defects; review capacity; dated rate-owner links; covered loss and cost; coverage decision; human fallback; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-02; measurement versus assumption=explicit | Unavailable — disagreement-triggered is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch56-claude-opus-4-8-vs-gpt-5-6-luna-m3-r6budget exhausted | pair=claude-opus-4-8 vs gpt-5.6-luna; provider=Anthropic / OpenAI; hostA=api.anthropic.com; hostB=api.openai.com; surfaceA=Messages API; surfaceB=Responses API; requested/effective IDs=claude-opus-4-8,gpt-5.6-luna; scenario=budget exhausted; traffic/risk strata; observed versus assumed defects; review capacity; dated rate-owner links; covered loss and cost; coverage decision; human fallback; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-02; measurement versus assumption=explicit | Unavailable — budget exhausted is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
First-party provenance: OpenAI API pricing; 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-gpt-5-6-luna Batch 56 scenario →
Batch 65 · exact-pair decision contributions · verified 2026-09-07
Exact pair boundary: Anthropic / OpenAI; model endpoint, premier reasoning flagship vs fast next-gen lightweight workhorse, and pricing must join. Requested models are claude-opus-4-8 and gpt-5.6-luna. Provider, rate, pricing, and task pages remain fact owners.
Token pricing and 5x enterprise budget impact matrix
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 workload expenditure modeling.
| Frozen scenario / field ID | Pair, identity, host, surface, and evidence fields | Result | State |
|---|---|---|---|
batch65-claude-opus-4-8-vs-gpt-5-6-luna-m1-r110K interactive reasoning queries | pair=claude-opus-4-8 vs gpt-5.6-luna; provider=Anthropic / OpenAI; hostA=api.anthropic.com; hostB=api.openai.com; surfaceA=Anthropic Messages API; surfaceB=OpenAI Responses API; requested/effective IDs=claude-opus-4-8,gpt-5.6-luna; scenario=10K interactive reasoning queries; workload; prompt tokens; completion tokens; Opus 4.8 spend; Luna spend; budget delta; cost winner; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — 10K interactive reasoning queries is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch65-claude-opus-4-8-vs-gpt-5-6-luna-m1-r250K automated code generation tasks | pair=claude-opus-4-8 vs gpt-5.6-luna; provider=Anthropic / OpenAI; hostA=api.anthropic.com; hostB=api.openai.com; surfaceA=Anthropic Messages API; surfaceB=OpenAI Responses API; requested/effective IDs=claude-opus-4-8,gpt-5.6-luna; scenario=50K automated code generation tasks; workload; prompt tokens; completion tokens; Opus 4.8 spend; Luna 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 automated code generation tasks is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch65-claude-opus-4-8-vs-gpt-5-6-luna-m1-r3100K classification events | pair=claude-opus-4-8 vs gpt-5.6-luna; provider=Anthropic / OpenAI; hostA=api.anthropic.com; hostB=api.openai.com; surfaceA=Anthropic Messages API; surfaceB=OpenAI Responses API; requested/effective IDs=claude-opus-4-8,gpt-5.6-luna; scenario=100K classification events; workload; prompt tokens; completion tokens; Opus 4.8 spend; Luna spend; budget delta; cost winner; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — 100K classification events is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch65-claude-opus-4-8-vs-gpt-5-6-luna-m1-r4prompt caching active (Opus 90% read / Luna 50% read) | pair=claude-opus-4-8 vs gpt-5.6-luna; provider=Anthropic / OpenAI; hostA=api.anthropic.com; hostB=api.openai.com; surfaceA=Anthropic Messages API; surfaceB=OpenAI Responses API; requested/effective IDs=claude-opus-4-8,gpt-5.6-luna; scenario=prompt caching active (Opus 90% read / Luna 50% read); workload; prompt tokens; completion tokens; Opus 4.8 spend; Luna 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 / Luna 50% read) is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch65-claude-opus-4-8-vs-gpt-5-6-luna-m1-r5batch processing active (50% both) | pair=claude-opus-4-8 vs gpt-5.6-luna; provider=Anthropic / OpenAI; hostA=api.anthropic.com; hostB=api.openai.com; surfaceA=Anthropic Messages API; surfaceB=OpenAI Responses API; requested/effective IDs=claude-opus-4-8,gpt-5.6-luna; scenario=batch processing active (50% both); workload; prompt tokens; completion tokens; Opus 4.8 spend; Luna 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-gpt-5-6-luna-m1-r6unresolved pricing currency | pair=claude-opus-4-8 vs gpt-5.6-luna; provider=Anthropic / OpenAI; hostA=api.anthropic.com; hostB=api.openai.com; surfaceA=Anthropic Messages API; surfaceB=OpenAI Responses API; requested/effective IDs=claude-opus-4-8,gpt-5.6-luna; scenario=unresolved pricing currency; workload; prompt tokens; completion tokens; Opus 4.8 spend; Luna 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.
Draft-and-review pipeline architecture and budget optimization
Frozen Batch 65 scenario board. Formula / deterministic rule: pipeline_cost = luna_draft_cost + (escalation_rate * opus_review_cost) Boundary: Owns two-tier architectural routing between Luna-first drafting and Opus review.
| Frozen scenario / field ID | Pair, identity, host, surface, and evidence fields | Result | State |
|---|---|---|---|
batch65-claude-opus-4-8-vs-gpt-5-6-luna-m2-r1100% Luna baseline generation | pair=claude-opus-4-8 vs gpt-5.6-luna; provider=Anthropic / OpenAI; hostA=api.anthropic.com; hostB=api.openai.com; surfaceA=Anthropic Messages API; surfaceB=OpenAI Responses API; requested/effective IDs=claude-opus-4-8,gpt-5.6-luna; scenario=100% Luna baseline generation; pipeline configuration; monthly volume; blended spend; cost savings vs pure Opus; review rigor; routing verdict; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — 100% Luna baseline generation is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch65-claude-opus-4-8-vs-gpt-5-6-luna-m2-r290% Luna draft / 10% Opus 4.8 review | pair=claude-opus-4-8 vs gpt-5.6-luna; provider=Anthropic / OpenAI; hostA=api.anthropic.com; hostB=api.openai.com; surfaceA=Anthropic Messages API; surfaceB=OpenAI Responses API; requested/effective IDs=claude-opus-4-8,gpt-5.6-luna; scenario=90% Luna draft / 10% Opus 4.8 review; pipeline configuration; monthly volume; blended spend; cost savings vs pure Opus; review rigor; routing verdict; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — 90% Luna draft / 10% Opus 4.8 review is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch65-claude-opus-4-8-vs-gpt-5-6-luna-m2-r380% Luna draft / 20% Opus 4.8 review | pair=claude-opus-4-8 vs gpt-5.6-luna; provider=Anthropic / OpenAI; hostA=api.anthropic.com; hostB=api.openai.com; surfaceA=Anthropic Messages API; surfaceB=OpenAI Responses API; requested/effective IDs=claude-opus-4-8,gpt-5.6-luna; scenario=80% Luna draft / 20% Opus 4.8 review; pipeline configuration; monthly volume; blended spend; cost savings vs pure Opus; review rigor; routing verdict; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — 80% Luna draft / 20% Opus 4.8 review is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch65-claude-opus-4-8-vs-gpt-5-6-luna-m2-r450% Luna draft / 50% Opus 4.8 review | pair=claude-opus-4-8 vs gpt-5.6-luna; provider=Anthropic / OpenAI; hostA=api.anthropic.com; hostB=api.openai.com; surfaceA=Anthropic Messages API; surfaceB=OpenAI Responses API; requested/effective IDs=claude-opus-4-8,gpt-5.6-luna; scenario=50% Luna draft / 50% Opus 4.8 review; pipeline configuration; monthly volume; blended spend; cost savings vs pure Opus; review rigor; routing verdict; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — 50% Luna draft / 50% Opus 4.8 review is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch65-claude-opus-4-8-vs-gpt-5-6-luna-m2-r5100% direct Opus 4.8 generation | pair=claude-opus-4-8 vs gpt-5.6-luna; provider=Anthropic / OpenAI; hostA=api.anthropic.com; hostB=api.openai.com; surfaceA=Anthropic Messages API; surfaceB=OpenAI Responses API; requested/effective IDs=claude-opus-4-8,gpt-5.6-luna; scenario=100% direct Opus 4.8 generation; pipeline configuration; monthly volume; blended spend; cost savings vs pure Opus; review rigor; routing verdict; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — 100% direct Opus 4.8 generation is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch65-claude-opus-4-8-vs-gpt-5-6-luna-m2-r6unresolved evaluation threshold trigger | pair=claude-opus-4-8 vs gpt-5.6-luna; provider=Anthropic / OpenAI; hostA=api.anthropic.com; hostB=api.openai.com; surfaceA=Anthropic Messages API; surfaceB=OpenAI Responses API; requested/effective IDs=claude-opus-4-8,gpt-5.6-luna; scenario=unresolved evaluation threshold trigger; pipeline configuration; monthly volume; blended spend; cost savings vs pure Opus; review rigor; routing verdict; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — unresolved evaluation threshold trigger has no matched, dated bilateral observation. | FAIL CLOSED — manual, probe, or source evidence required |
First-party provenance: OpenAI model documentation; verification date 2026-09-07. Missing or conflicting joins fail closed.
Context window saturation (500K vs 1M) capability gate
Frozen Batch 65 scenario board. Formula / deterministic rule: eligible = (context <= 500K ? Both : (context <= 1M ? Luna : 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-gpt-5-6-luna-m3-r1short prompt (10K tokens) | pair=claude-opus-4-8 vs gpt-5.6-luna; provider=Anthropic / OpenAI; hostA=api.anthropic.com; hostB=api.openai.com; surfaceA=Anthropic Messages API; surfaceB=OpenAI Responses API; requested/effective IDs=claude-opus-4-8,gpt-5.6-luna; scenario=short prompt (10K tokens); context size; Opus 4.8 eligible; Luna eligible; Opus cost; Luna cost; context gate verdict; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — short prompt (10K tokens) is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch65-claude-opus-4-8-vs-gpt-5-6-luna-m3-r2large legal document (100K tokens) | pair=claude-opus-4-8 vs gpt-5.6-luna; provider=Anthropic / OpenAI; hostA=api.anthropic.com; hostB=api.openai.com; surfaceA=Anthropic Messages API; surfaceB=OpenAI Responses API; requested/effective IDs=claude-opus-4-8,gpt-5.6-luna; scenario=large legal document (100K tokens); context size; Opus 4.8 eligible; Luna eligible; Opus cost; Luna cost; context gate verdict; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — large legal document (100K tokens) is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch65-claude-opus-4-8-vs-gpt-5-6-luna-m3-r3monolithic codebase (500K boundary) | pair=claude-opus-4-8 vs gpt-5.6-luna; provider=Anthropic / OpenAI; hostA=api.anthropic.com; hostB=api.openai.com; surfaceA=Anthropic Messages API; surfaceB=OpenAI Responses API; requested/effective IDs=claude-opus-4-8,gpt-5.6-luna; scenario=monolithic codebase (500K boundary); context size; Opus 4.8 eligible; Luna eligible; Opus cost; Luna cost; context gate verdict; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — 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-gpt-5-6-luna-m3-r4repository dump (750K tokens) | pair=claude-opus-4-8 vs gpt-5.6-luna; provider=Anthropic / OpenAI; hostA=api.anthropic.com; hostB=api.openai.com; surfaceA=Anthropic Messages API; surfaceB=OpenAI Responses API; requested/effective IDs=claude-opus-4-8,gpt-5.6-luna; scenario=repository dump (750K tokens); context size; Opus 4.8 eligible; Luna eligible; Opus cost; Luna cost; context gate verdict; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — repository dump (750K tokens) is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch65-claude-opus-4-8-vs-gpt-5-6-luna-m3-r51M full context saturation test | pair=claude-opus-4-8 vs gpt-5.6-luna; provider=Anthropic / OpenAI; hostA=api.anthropic.com; hostB=api.openai.com; surfaceA=Anthropic Messages API; surfaceB=OpenAI Responses API; requested/effective IDs=claude-opus-4-8,gpt-5.6-luna; scenario=1M full context saturation test; context size; Opus 4.8 eligible; Luna eligible; Opus cost; Luna cost; context gate verdict; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — 1M 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-gpt-5-6-luna-m3-r6unsupported archive payload format | pair=claude-opus-4-8 vs gpt-5.6-luna; provider=Anthropic / OpenAI; hostA=api.anthropic.com; hostB=api.openai.com; surfaceA=Anthropic Messages API; surfaceB=OpenAI Responses API; requested/effective IDs=claude-opus-4-8,gpt-5.6-luna; scenario=unsupported archive payload format; context size; Opus 4.8 eligible; Luna eligible; Opus cost; Luna cost; context gate 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: Anthropic Claude model 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-gpt-5-6-luna Batch 65 scenario →
How do Claude Opus 4.8 and GPT-5.6 Luna compare on specs?
| Claude Opus 4.8 | GPT-5.6 Luna | |
|---|---|---|
| Price (input) | $5.00/M | $1.00/M ✓ |
| Price (output) | $25.00/M | $6.00/M ✓ |
| Blended price | $10.00/M | $2.25/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 | No |
| Released | 2026-04 | 2026-06 |
| Speed | 58 t/s | 126 t/s ✓ |
How much do Claude Opus 4.8 and GPT-5.6 Luna cost at scale?
| Tokens / month | Claude Opus 4.8 | GPT-5.6 Luna | Delta |
|---|---|---|---|
| 1,000,000 | $10.00 | $2.25 | $7.75 (4.4×) |
| 10,000,000 | $100.00 | $22.50 | $77.50 (4.4×) |
| 100,000,000 | $1000.00 | $225.00 | $775.00 (4.4×) |
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 GPT-5.6 Luna if…
- ✓Cheapest current GPT-5.6 tier
- ✓Low latency for high-volume calls
- ✓1M context window and vision input
- ✓High-volume, latency-sensitive tasks like classification, extraction, and chat.
Run this exact matchup right now
Send the same prompt to Claude Opus 4.8 and GPT-5.6 Luna side by side and see the outputs yourself.
Try Claude Opus 4.8 vs GPT-5.6 Luna FreeWhat are common questions about Claude Opus 4.8 and GPT-5.6 Luna?
Is Claude Opus 4.8 cheaper than GPT-5.6 Luna?
GPT-5.6 Luna is cheaper, at $2.25 per million blended tokens vs $10.00 for Claude Opus 4.8.
Which has the bigger context window, Claude Opus 4.8 or GPT-5.6 Luna?
GPT-5.6 Luna has the larger context window: 1,000,000 tokens vs 500,000.
Can Claude Opus 4.8 replace GPT-5.6 Luna for coding?
Both are viable for coding. Elite coding and multi-step reasoning (Claude Opus 4.8) vs Cheapest current GPT-5.6 tier (GPT-5.6 Luna) — pick based on which strength matters more for your workload.
Which is faster, Claude Opus 4.8 or GPT-5.6 Luna?
GPT-5.6 Luna is faster: 126 t/s vs 58 t/s, measured on our speed benchmarks.
Neither of these? See Claude Opus 4.8 alternatives or GPT-5.6 Luna alternatives.
What related comparisons help choose between Claude Opus 4.8 and GPT-5.6 Luna?
Claude Opus 4.8 pricingGPT-5.6 Luna pricingvs Claude Opus 4vs DeepSeek V4 Provs Gemini 3.1 Provs Gemini 3.7 FlashPremium model tests
Pricing verified 2026-06-07. Specs verified 2026-08-14.