Claude Opus 5.5 vs GPT-6.1 Sol
Humanity's Last Exam Humanity's Last Exam: Very hard expert questions across many fields, written to stump today’s models
Opus 5.554.7
GPT-6.1 Sol49.9
Arena Text · overall Arena Text · overall: Human pairwise preferences in the stated text vote pool
Opus 5.5 · high1,508
GPT-6.1 Sol · max1,484
Arena Text · Chinese Arena Text · chinese: Human pairwise preferences in the stated text vote pool
Opus 5.5 · high1,583.6
GPT-6.1 Sol · max1,494.6
Arena Text · English Arena Text · english: Human pairwise preferences in the stated text vote pool
Opus 5.5 · high1,516.9
GPT-6.1 Sol · max1,454.2
Arena Text · French Arena Text · french: Human pairwise preferences in the stated text vote pool
Opus 5.5 · high1,505.3
GPT-6.1 Sol · max1,470.1
Arena Text · instruction following Arena Text · instruction following: Human pairwise preferences in the stated text vote pool
Opus 5.5 · high1,535.8
GPT-6.1 Sol · max1,468.6
Arena Text · non-English Arena Text · non english: Human pairwise preferences in the stated text vote pool
Opus 5.5 · high1,506.9
GPT-6.1 Sol · max1,437.5
Arena Text · Russian Arena Text · russian: Human pairwise preferences in the stated text vote pool
Opus 5.5 · high1,519.1
GPT-6.1 Sol · max1,457.9
Arena Text · Spanish Arena Text · spanish: Human pairwise preferences in the stated text vote pool
Opus 5.5 · high1,519
GPT-6.1 Sol · max1,440.4
AA Omniscience Index AA Omniscience Index: Scores factual knowledge while penalizing incorrect answers to encourage admitting uncertainty
Opus 5.540.3
GPT-6.1 Sol40
SimpleQA Verified v1 SimpleQA Verified v1: Accuracy on short factual questions with verified answers, answered without web access
Opus 5.5 · max72.2
GPT-6.1 Sol · max73.9
CritPt (physics) CritPt (physics): Research-level physics problems that need many careful reasoning steps
Opus 5.527.7
GPT-6.1 Sol27.7
AA Intelligence Index 4.3.2 AA Intelligence Index 4.3.2: Artificial Analysis combines tests of knowledge, reasoning, coding and tool use into one score
Opus 5.551.2
GPT-6.1 Sol47.8
AA Omniscience · Accuracy AA Omniscience · Accuracy: Measures correct answers on the AA Omniscience factual knowledge test
Opus 5.564.6
GPT-6.1 Sol60.4
AA Omniscience · Hallucination Rate AA Omniscience · Hallucination Rate: Measures how often attempted answers are incorrect on the AA Omniscience factual knowledge test · lower is better
Opus 5.568.4
GPT-6.1 Sol51.6
AA-LCR (long context) 1.1 AA-LCR (long context) 1.1: Questions that need reading and connecting facts across very long documents (around 100K tokens)
Opus 5.584.3
GPT-6.1 Sol83.3
GDP.pdf · AA all-pass GDP.pdf · AA all-pass: Models reason over professional PDF documents; an attempt passes only when every atomic criterion passes
Opus 5.525.6
GPT-6.1 Sol30
MLCR-AA MLCR-AA: Models synthesize long medical records; the headline credits concise answers judged both accurate and complete
Opus 5.5 · max66.7
GPT-6.1 Sol · max33.9
ARC-AGI-1 · public evaluation ARC-AGI-1 · public-eval: Models infer transformations from examples and solve unseen grid puzzles; the evaluation split is explicit
Opus 5.598.3
GPT-6.1 Sol97.9
ARC-AGI-1 · semi-private ARC-AGI-1 · semi-private: Models infer transformations from examples and solve unseen grid puzzles; the evaluation split is explicit
Opus 5.597.5
GPT-6.1 Sol95.5
ARC-AGI-2 · public evaluation ARC-AGI-2 · public-eval: Models infer transformations from examples and solve unseen grid puzzles; the evaluation split is explicit
Opus 5.593.5
GPT-6.1 Sol90.6
ARC-AGI-2 · semi-private ARC-AGI-2 · semi-private: Models infer transformations from examples and solve unseen grid puzzles; the evaluation split is explicit
Opus 5.587.5
GPT-6.1 Sol86.7
Chess Puzzles Chess Puzzles: Models choose the best next move from a novel chess position
Opus 5.5 · max67
GPT-6.1 Sol · max68
FrontierMath Erdos FrontierMath Erdos: Models solve expert-written advanced mathematics problems on the named tier and edition
Opus 5.5 · max2.9
GPT-6.1 Sol · max4.4
FrontierMath Tier 4 (v2) FrontierMath Tier 4 (v2): Models solve expert-written advanced mathematics problems on the named tier and edition
Opus 5.5 · max95
GPT-6.1 Sol · max100
FrontierMath Tiers 1–3 (v2) FrontierMath Tiers 1–3 (v2): Models solve expert-written advanced mathematics problems on the named tier and edition
Opus 5.5 · max91.2
GPT-6.1 Sol · max93.7
Mystery Game Puzzles Mystery Game Puzzles: Models choose the best move in puzzle positions from an undisclosed game
Opus 5.5 · max71
GPT-6.1 Sol · max80
MathArena · ArXivMath · August 2026 MathArena · arxiv · 08/2026: Answer accuracy on the named mathematics competition under the recorded effort
Opus 5.5 · high86
GPT-6.1 Sol · max96.5
MathArena · ArXivMath · June 2026 MathArena · arxiv · 06/2026: Answer accuracy on the named mathematics competition under the recorded effort
Opus 5.5 · high83.3
GPT-6.1 Sol · max94.4
MathArena · ArXivMath · May 2026 MathArena · arxiv · 05/2026: Answer accuracy on the named mathematics competition under the recorded effort
Opus 5.5 · high81.7
GPT-6.1 Sol · max95
MathArena · ArXivMath · September 2026 MathArena · arxiv · 09/2026: Answer accuracy on the named mathematics competition under the recorded effort
Opus 5.5 · high82.1
GPT-6.1 Sol · max91.5
MathArena · BrokenArXiv · August 2026 MathArena · arxiv_false · 08/2026: Answer accuracy on the named mathematics competition under the recorded effort
Opus 5.5 · high77.4
GPT-6.1 Sol · max86.3
MathArena · BrokenArXiv · June 2026 MathArena · arxiv_false · 06/2026: Answer accuracy on the named mathematics competition under the recorded effort
Opus 5.5 · high100
GPT-6.1 Sol · max100
MathArena · BrokenArXiv · May 2026 MathArena · arxiv_false · 05/2026: Answer accuracy on the named mathematics competition under the recorded effort
Opus 5.5 · high95
GPT-6.1 Sol · max90
MathArena · BrokenArXiv · September 2026 MathArena · arxiv_false · 09/2026: Answer accuracy on the named mathematics competition under the recorded effort
Opus 5.5 · high76.7
GPT-6.1 Sol · max82.7
MathArena · ArXivLean · September 2026 MathArena · arxivlean · 09/2026: Answer accuracy on the named mathematics competition under the recorded effort
Opus 5.5 · high47.2
GPT-6.1 Sol · max35.9
Vals MedCode Vals MedCode: Medical coding accuracy on patient encounters
Opus 5.549.8
GPT-6.1 Sol48.8
Vals MedScribe Vals MedScribe: Accuracy of clinical notes produced from consultation transcripts
Opus 5.591.4
GPT-6.1 Sol86.5
Vals Legal Research Bench Vals Legal Research Bench: Grounded legal research; a task passes only if all criteria pass
Opus 5.550.5
GPT-6.1 Sol38.5
Vals Science Index Vals Science Index: Scientific problem solving across the index’s component evaluations
Opus 5.558.7
GPT-6.1 Sol59.6
ARC-AGI-3 · semi-private ARC-AGI-3 · semi-private: Measures interactive game solving through relative human action efficiency
Opus 5.5—
GPT-6.1 Sol10.6
| Benchmark | Opus 5.5 | GPT-6.1 Sol |
|---|---|---|
| Humanity's Last Exam | 54.7 | 49.9 |
| Arena Text · overall | 1,508 · high | 1,484 · max |
| Arena Text · Chinese | 1,583.6 · high | 1,494.6 · max |
| Arena Text · English | 1,516.9 · high | 1,454.2 · max |
| Arena Text · French | 1,505.3 · high | 1,470.1 · max |
| Arena Text · instruction following | 1,535.8 · high | 1,468.6 · max |
| Arena Text · non-English | 1,506.9 · high | 1,437.5 · max |
| Arena Text · Russian | 1,519.1 · high | 1,457.9 · max |
| Arena Text · Spanish | 1,519 · high | 1,440.4 · max |
| AA Omniscience Index | 40.3 | 40 |
| SimpleQA Verified v1 | 72.2 · max | 73.9 · max |
| CritPt (physics) | 27.7 | 27.7 |
| AA Intelligence Index 4.3.2 | 51.2 | 47.8 |
| AA Omniscience · Accuracy | 64.6 | 60.4 |
| AA Omniscience · Hallucination Rate | 68.4 | 51.6 |
| AA-LCR (long context) 1.1 | 84.3 | 83.3 |
| GDP.pdf · AA all-pass | 25.6 | 30 |
| MLCR-AA | 66.7 · max | 33.9 · max |
| ARC-AGI-1 · public evaluation | 98.3 | 97.9 |
| ARC-AGI-1 · semi-private | 97.5 | 95.5 |
| ARC-AGI-2 · public evaluation | 93.5 | 90.6 |
| ARC-AGI-2 · semi-private | 87.5 | 86.7 |
| Chess Puzzles | 67 · max | 68 · max |
| FrontierMath Erdos | 2.9 · max | 4.4 · max |
| FrontierMath Tier 4 (v2) | 95 · max | 100 · max |
| FrontierMath Tiers 1–3 (v2) | 91.2 · max | 93.7 · max |
| Mystery Game Puzzles | 71 · max | 80 · max |
| MathArena · ArXivMath · August 2026 | 86 · high | 96.5 · max |
| MathArena · ArXivMath · June 2026 | 83.3 · high | 94.4 · max |
| MathArena · ArXivMath · May 2026 | 81.7 · high | 95 · max |
| MathArena · ArXivMath · September 2026 | 82.1 · high | 91.5 · max |
| MathArena · BrokenArXiv · August 2026 | 77.4 · high | 86.3 · max |
| MathArena · BrokenArXiv · June 2026 | 100 · high | 100 · max |
| MathArena · BrokenArXiv · May 2026 | 95 · high | 90 · max |
| MathArena · BrokenArXiv · September 2026 | 76.7 · high | 82.7 · max |
| MathArena · ArXivLean · September 2026 | 47.2 · high | 35.9 · max |
| Vals MedCode | 49.8 | 48.8 |
| Vals MedScribe | 91.4 | 86.5 |
| Vals Legal Research Bench | 50.5 | 38.5 |
| Vals Science Index | 58.7 | 59.6 |
| ARC-AGI-3 · semi-private | — | 10.6 |
Specs
| Spec | Opus 5.5 | GPT-6.1 Sol |
|---|---|---|
| Input, per 1M | $4 | $2 |
| Output, per 1M | $20 | $10 |
| Cost per task? | $1.34 | $0.21 |
| Speed, tok/s | 81 | 45 |
| Context | 1M | 1.05M |
| Weights | Closed | Closed |
| Released | Sep 2026 | Sep 2026 |
| See images | ✓ | ✓ |
| Read PDFs | ✓ | Partial |
| Hear audio | — | — |
| Watch video | — | — |
| Call tools | ✓ | ✓ |
| Force a tool call | — | Partial |
| Return strict JSON | ✓ | ✓ |
| Search the web | ✓ | ✓ |
| Run code | ✓ | ✓ |
| Use a computer | ✓ | ✓ |
What breaks when you switch
Opus 5.5 → GPT-6.1 Sol
Remove unsupported parameters›
With reasoning enabled, remove temperature, top_p and top_logprobs, plus Chat Completions logprobs or Responses message.output_text.logprobs includes.
Responses API for tool calling · Chat Completions›
Use Responses for tools; Chat Completions supports this model without tool calling.
No none or minimal reasoning›
The none and minimal reasoning efforts are unsupported; choose low, medium, high, xhigh or max.
More than 272K input tokens›
Prompts above 272K input tokens charge 2× input and cache rates and 1.5× output rates for the entire request.
Cache writes billed at 1.25x›
Cache writes cost 1.25× the uncached input token rate.
Ultrafast prices 6x Standard›
Ultrafast mode costs 6× Standard token prices.
GPT-6.1 Sol → Opus 5.5
Context: 1.05M → 1M
No forced tool use›
Forced tool_choice any or tool returns HTTP 400; remove the forced choice.
Thinking is always on›
Disabled thinking or a manual budget returns HTTP 400; omit thinking or use adaptive thinking.
Remove sampling parameters›
Non-default temperature, top_p or top_k returns HTTP 400; omit these parameters and use prompting.
No assistant prefill›
Assistant prefill returns HTTP 400; use structured outputs or system instructions, with system instructions on Bedrock.
Old computer tool rejected · Claude API / Google Cloud›
The computer_20251124 tool returns HTTP 400 on the Claude API and Google Cloud; use computer_toolset_20260801 there.
Return thinking blocks unmodified›
Edited, reordered or partially dropped thinking blocks return HTTP 400; echo assistant messages complete and unmodified with tool results.