Compare Claude Opus 4.8 and GPT-5.6 Sol: Frontier Reasoning and Agent Architecture
Claude Opus 4.8 vs GPT-5.6 Sol: which should I use?
Claude Opus 4.8 and GPT-5.6 Sol represent the premier reasoning flagships of Anthropic and OpenAI. Opus 4.8 offers granular extended thinking controls and 90% cache read discounts; Sol delivers 1M context and 128K max output headroom. 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 Sol?
Which tasks fit Claude Opus 4.8 and GPT-5.6 Sol?
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 Sol |
|---|---|---|
| Best fit | Complex, multi-step tasks where Fable 5’s premium isn’t justified. | Complex, multi-step professional and coding work where accuracy matters more than cost. |
| Reasoning mode | Available | Available |
What does a Coding Agent workload cost with Claude Opus 4.8 and GPT-5.6 Sol?
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 Sol |
|---|---|---|
| Coding Agent / task | $0.15 (modeled) | $0.12 (modeled) (winner) |
| Input / output rate | $5.00 / $25.00 per M | $4.00 / $20.00 per M |
How fast are Claude Opus 4.8 and GPT-5.6 Sol?
Only non-estimated benchmark results are shown as measured.
| Fact | Claude Opus 4.8 | GPT-5.6 Sol |
|---|---|---|
| Measured throughput | 58 tokens/s (winner) | 44 tokens/s |
| Time to first token | 470 ms | 560 ms |
How compatible are Claude Opus 4.8 and GPT-5.6 Sol with APIs?
Provider-level wire-format and SDK facts; model-specific parameter differences may still apply.
| Fact | Claude Opus 4.8 | GPT-5.6 Sol |
|---|---|---|
| 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 Sol?
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 Sol |
|---|---|---|
| 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 Sol?
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 Sol |
|---|---|---|
| Move Claude Opus 4.8 → GPT-5.6 Sol | config; 3 breaking parameter differences | Target: GPT-5.6 Sol |
| Move GPT-5.6 Sol → Claude Opus 4.8 | Source: GPT-5.6 Sol | 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 63 · exact-pair decision contributions · verified 2026-09-07
Exact pair boundary: Anthropic / OpenAI; model endpoint, 500K vs 1M context, extended thinking vs native reasoning, and token tariffs must join. Requested models are claude-opus-4-8 and gpt-5.6-sol. Provider, rate, pricing, and task pages remain fact owners.
Reasoning token budgeting and output expansion economics
Frozen Batch 63 scenario board. Formula / deterministic rule: total_out_cost = (visible_tokens + reasoning_tokens) * out_rate / 1M; Opus 4.8 $25/M, Sol $20/M promo Boundary: Owns output and reasoning token spend modeling.
| Frozen scenario / field ID | Pair, identity, host, surface, and evidence fields | Result | State |
|---|---|---|---|
batch63-claude-opus-4-8-vs-gpt-5-6-sol-m1-r1standard generation without reasoning (4K tokens) | pair=claude-opus-4-8 vs gpt-5.6-sol; 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-sol; scenario=standard generation without reasoning (4K tokens); task; visible tokens; reasoning tokens; Opus 4.8 output cost; Sol output cost; cost delta; efficiency winner; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — standard generation without reasoning (4K tokens) is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch63-claude-opus-4-8-vs-gpt-5-6-sol-m1-r2deep analytical reasoning (16K reasoning tokens) | pair=claude-opus-4-8 vs gpt-5.6-sol; 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-sol; scenario=deep analytical reasoning (16K reasoning tokens); task; visible tokens; reasoning tokens; Opus 4.8 output cost; Sol output cost; cost delta; efficiency winner; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — deep analytical reasoning (16K reasoning tokens) is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch63-claude-opus-4-8-vs-gpt-5-6-sol-m1-r3exhaustive mathematical proof (32K reasoning tokens) | pair=claude-opus-4-8 vs gpt-5.6-sol; 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-sol; scenario=exhaustive mathematical proof (32K reasoning tokens); task; visible tokens; reasoning tokens; Opus 4.8 output cost; Sol output cost; cost delta; efficiency winner; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — exhaustive mathematical proof (32K reasoning tokens) is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch63-claude-opus-4-8-vs-gpt-5-6-sol-m1-r4repository refactor plan (64K reasoning tokens) | pair=claude-opus-4-8 vs gpt-5.6-sol; 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-sol; scenario=repository refactor plan (64K reasoning tokens); task; visible tokens; reasoning tokens; Opus 4.8 output cost; Sol output cost; cost delta; efficiency winner; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — repository refactor plan (64K reasoning tokens) is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch63-claude-opus-4-8-vs-gpt-5-6-sol-m1-r5maximum output ceiling test | pair=claude-opus-4-8 vs gpt-5.6-sol; 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-sol; scenario=maximum output ceiling test; task; visible tokens; reasoning tokens; Opus 4.8 output cost; Sol output cost; cost delta; efficiency winner; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — maximum output ceiling test is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch63-claude-opus-4-8-vs-gpt-5-6-sol-m1-r6unbounded thinking runaway buffer | pair=claude-opus-4-8 vs gpt-5.6-sol; 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-sol; scenario=unbounded thinking runaway buffer; task; visible tokens; reasoning tokens; Opus 4.8 output cost; Sol output cost; cost delta; efficiency winner; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — unbounded thinking runaway buffer is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
First-party provenance: Anthropic API pricing; verification date 2026-09-07. Missing or conflicting joins fail closed.
Prompt caching write/read break-even and retention board
Frozen Batch 63 scenario board. Formula / deterministic rule: caching_roi = cache_reads * (base_in_rate - read_rate) - cache_writes * (write_rate - base_in_rate) Boundary: Owns prompt caching mechanics and ROI comparisons.
| Frozen scenario / field ID | Pair, identity, host, surface, and evidence fields | Result | State |
|---|---|---|---|
batch63-claude-opus-4-8-vs-gpt-5-6-sol-m2-r12-turn conversation (1 write, 1 read) | pair=claude-opus-4-8 vs gpt-5.6-sol; 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-sol; scenario=2-turn conversation (1 write, 1 read); session turns; prompt size; Opus 4.8 cache cost; Sol cache cost; net caching savings; caching champion; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — 2-turn conversation (1 write, 1 read) is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch63-claude-opus-4-8-vs-gpt-5-6-sol-m2-r25-turn agent loop (1 write, 4 reads) | pair=claude-opus-4-8 vs gpt-5.6-sol; 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-sol; scenario=5-turn agent loop (1 write, 4 reads); session turns; prompt size; Opus 4.8 cache cost; Sol cache cost; net caching savings; caching champion; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — 5-turn agent loop (1 write, 4 reads) is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch63-claude-opus-4-8-vs-gpt-5-6-sol-m2-r320-turn deep interactive thread (1 write, 19 reads) | pair=claude-opus-4-8 vs gpt-5.6-sol; 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-sol; scenario=20-turn deep interactive thread (1 write, 19 reads); session turns; prompt size; Opus 4.8 cache cost; Sol cache cost; net caching savings; caching champion; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — 20-turn deep interactive thread (1 write, 19 reads) is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch63-claude-opus-4-8-vs-gpt-5-6-sol-m2-r4cache eviction after 5-minute TTL | pair=claude-opus-4-8 vs gpt-5.6-sol; 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-sol; scenario=cache eviction after 5-minute TTL; session turns; prompt size; Opus 4.8 cache cost; Sol cache cost; net caching savings; caching champion; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — cache eviction after 5-minute TTL is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch63-claude-opus-4-8-vs-gpt-5-6-sol-m2-r5cache read miss cold start | pair=claude-opus-4-8 vs gpt-5.6-sol; 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-sol; scenario=cache read miss cold start; session turns; prompt size; Opus 4.8 cache cost; Sol cache cost; net caching savings; caching champion; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — cache read miss cold start is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch63-claude-opus-4-8-vs-gpt-5-6-sol-m2-r6unsupported cache payload structure | pair=claude-opus-4-8 vs gpt-5.6-sol; 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-sol; scenario=unsupported cache payload structure; session turns; prompt size; Opus 4.8 cache cost; Sol cache cost; net caching savings; caching champion; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — unsupported cache payload structure 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.
Enterprise software engineering dual-run canary ledger
Frozen Batch 63 scenario board. Formula / deterministic rule: canary_spend = dual_calls * (opus_call_cost + sol_call_cost); agreement_rate determines cutover Boundary: Owns dual-run evaluation framework between Opus 4.8 and Sol.
| Frozen scenario / field ID | Pair, identity, host, surface, and evidence fields | Result | State |
|---|---|---|---|
batch63-claude-opus-4-8-vs-gpt-5-6-sol-m3-r1100 unit-test generation runs | pair=claude-opus-4-8 vs gpt-5.6-sol; 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-sol; scenario=100 unit-test generation runs; evaluation workload; Opus 4.8 spend; Sol spend; dual-run cost; consensus rate; migration status; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — 100 unit-test generation runs is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch63-claude-opus-4-8-vs-gpt-5-6-sol-m3-r2500 multi-file code review tasks | pair=claude-opus-4-8 vs gpt-5.6-sol; 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-sol; scenario=500 multi-file code review tasks; evaluation workload; Opus 4.8 spend; Sol spend; dual-run cost; consensus rate; migration status; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — 500 multi-file code review tasks is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch63-claude-opus-4-8-vs-gpt-5-6-sol-m3-r31K complex refactoring pull requests | pair=claude-opus-4-8 vs gpt-5.6-sol; 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-sol; scenario=1K complex refactoring pull requests; evaluation workload; Opus 4.8 spend; Sol spend; dual-run cost; consensus rate; migration status; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — 1K complex refactoring pull requests is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch63-claude-opus-4-8-vs-gpt-5-6-sol-m3-r45K automated CI/CD bug triage runs | pair=claude-opus-4-8 vs gpt-5.6-sol; 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-sol; scenario=5K automated CI/CD bug triage runs; evaluation workload; Opus 4.8 spend; Sol spend; dual-run cost; consensus rate; migration status; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — 5K automated CI/CD bug triage runs is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch63-claude-opus-4-8-vs-gpt-5-6-sol-m3-r5high agreement (>95%) cutover threshold | pair=claude-opus-4-8 vs gpt-5.6-sol; 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-sol; scenario=high agreement (>95%) cutover threshold; evaluation workload; Opus 4.8 spend; Sol spend; dual-run cost; consensus rate; migration status; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — high agreement (>95%) cutover threshold is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
batch63-claude-opus-4-8-vs-gpt-5-6-sol-m3-r6divergent code output conflict resolution | pair=claude-opus-4-8 vs gpt-5.6-sol; 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-sol; scenario=divergent code output conflict resolution; evaluation workload; Opus 4.8 spend; Sol spend; dual-run cost; consensus rate; migration status; prompt/config/input/output/result/cache/checkpoint/artifact hashes=required; evidence=2026-09-07; measurement versus assumption=explicit | Unavailable — divergent code output conflict resolution is a frozen fixture pending exact identity, configuration, and denominator joins. | UNTESTED — assumption cannot establish a verdict |
First-party provenance: OpenAI rate limits; 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-sol Batch 63 scenario →
How do Claude Opus 4.8 and GPT-5.6 Sol compare on specs?
| Claude Opus 4.8 | GPT-5.6 Sol | |
|---|---|---|
| Price (input) | $5.00/M | $4.00/M ✓ |
| Price (output) | $25.00/M | $20.00/M ✓ |
| Blended price | $10.00/M | $8.00/M ✓ |
| Context window | 500,000 tokens | 1,000,000 tokens ✓ |
| Max output | 64,000 tokens | 128,000 tokens ✓ |
| Modalities | text, vision | text, vision |
| Reasoning mode | Yes | Yes |
| Released | 2026-04 | 2026-06 |
| Speed | 58 t/s ✓ | 44 t/s |
How much do Claude Opus 4.8 and GPT-5.6 Sol cost at scale?
| Tokens / month | Claude Opus 4.8 | GPT-5.6 Sol | Delta |
|---|---|---|---|
| 1,000,000 | $10.00 | $8.00 | $2.00 (1.3×) |
| 10,000,000 | $100.00 | $80.00 | $20.00 (1.3×) |
| 100,000,000 | $1000.00 | $800.00 | $200.00 (1.3×) |
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 GPT-5.6 Sol if…
- ✓Strongest OpenAI model for agentic, long-horizon coding
- ✓Deep reasoning mode for multi-step planning
- ✓Native vision input and 1M context
- ✓Complex, multi-step professional and coding work where accuracy matters more than cost.
Run this exact matchup right now
Send the same prompt to Claude Opus 4.8 and GPT-5.6 Sol side by side and see the outputs yourself.
Try Claude Opus 4.8 vs GPT-5.6 Sol FreeWhat are common questions about Claude Opus 4.8 and GPT-5.6 Sol?
Is Claude Opus 4.8 cheaper than GPT-5.6 Sol?
GPT-5.6 Sol is cheaper, at $8.00 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 Sol?
GPT-5.6 Sol has the larger context window: 1,000,000 tokens vs 500,000.
Can Claude Opus 4.8 replace GPT-5.6 Sol for coding?
Both are viable for coding. Elite coding and multi-step reasoning (Claude Opus 4.8) vs Strongest OpenAI model for agentic, long-horizon coding (GPT-5.6 Sol) — pick based on which strength matters more for your workload.
Which is faster, Claude Opus 4.8 or GPT-5.6 Sol?
Claude Opus 4.8 is faster: 58 t/s vs 44 t/s, measured on our speed benchmarks.
Neither of these? See Claude Opus 4.8 alternatives or GPT-5.6 Sol alternatives.
What related comparisons help choose between Claude Opus 4.8 and GPT-5.6 Sol?
Claude Opus 4.8 pricingGPT-5.6 Sol 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.