Claude Opus 5.5 vs Mistral Medium 3.1
Claude Opus 5.5 leads Mistral Medium 3.1 on the Artificial Analysis Intelligence Index, 57.6 to 9.2, and Mistral Medium 3.1 costs 10.0x less per output token ($2.00 vs $20.00 per million). Updated October 21, 2026; 45 benchmarks have a result for both.
vs boards won of 45 shared
Claude Opus 5.5 or Mistral Medium 3.1: which to pick
Only Claude Opus 5.5 has a coding score, 88.8 on the Vibe Coding Index; Mistral Medium 3.1 has none, so the two cannot be ranked on coding.
Pick Mistral Medium 3.1 for output tokens 10.0x cheaper ($2.00 vs $20.00 per million).
Model AClaude Opus 5.5Anthropic88.8/1005 independent benchmarksNo cost per solved taskModel BMistral Medium 3.1Mistral AINot benchmarkedNo coding benchmarkNo cost per solved task
- Shared results
- 45
- Claude Opus 5.5 only
- 64
- Mistral Medium 3.1 only
- 29
- Like-for-like categories
- 7 of 9
Only benchmarks that tested both models count toward a pick; a result only one model has is shown but not compared.
Which one for your work
Each card is decided by one number both models carry. Where only one has it, the card says so and makes no call.
Coding
Vibe Coding Index, six public coding benchmarks
No call
Only Claude Opus 5.5 has a coding score, so no call is made.
One side not measured
Intelligence
AA Intelligence Index
Claude Opus 5.5
Claude Opus 5.5 leads, 57.6 against 9.2.
Same board, both measured
Agentic work
AA Agentic Index
No call
Only Mistral Medium 3.1 has a AA Agentic Index result, 1.9.
Directional only
Math
AIME
No call
Only Mistral Medium 3.1 has a AIME result, 42.3%.
Directional only
Knowledge
MMLU Pro
No call
Only Mistral Medium 3.1 has a MMLU Pro result, 75.3%.
Directional only
Web design
Design Arena: websites
Claude Opus 5.5
Claude Opus 5.5 leads, 1336 against 1133.
Same board, both measured
General
Vals Index
No call
Only Claude Opus 5.5 has a Vals Index result, 70.2%.
Directional only
Long documents
Listed context window
Claude Opus 5.5
Claude Opus 5.5 takes 1M tokens against 131K.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
Mistral Medium 3.1
Claude Opus 5.5 $0.014, Mistral Medium 3.1 $0.0014 per turn.
List prices
At a glance
- Coding index
- Claude Opus 5.5 88.8 from 5 benchmarks, Mistral Medium 3.1 not benchmarked.
- Widest category
- Intelligence, 48.4 points apart on average over 1 shared benchmark.
- Widest single gap
- ALE-Bench: Claude Opus 5.5 2147.4 against Mistral Medium 3.1 210.2, 64.6 points apart on a 0 to 100 scale.
- Output price
- Claude Opus 5.5 $20.00 against Mistral Medium 3.1 $2.00 per million output tokens, 10.0x apart.
- Context window
- Claude Opus 5.5 takes 1M tokens, Mistral Medium 3.1 131K.
Benchmark by benchmark
First the score: boards each model leads, per category, where both have a result. Then every board, a category to a fold; bars are each result on a 0 to 100 scale, so compare the two in a row, not one row with another.
| Category | Claude Opus 5.5 | Bars | Mistral Medium 3.1 | Ties |
|---|---|---|---|---|
| Coding | 4 | 0 | ||
| Intelligence | 1 | 0 | ||
| Reasoning | 6 | 0 | ||
| Math | 2 | 0 | ||
| Knowledge | 4 | 0 | ||
| Web design | 7 | 0 | ||
| General | 21 | 0 | ||
| All shared boards | 45 | 0 |
CodingLike-for-likeSix of these boards feed the Vibe Coding Index40
| Benchmark | Claude Opus 5.5 | Mistral Medium 3.1 | Leader |
|---|---|---|---|
| LiveBench coding | 96.3% | Not measured | Only Claude Opus 5.5 measured |
| LMArena WebDev | 1807 | Not measured | Only Claude Opus 5.5 measured |
| AA Coding Index | Not measured | 20.5 | Only Mistral Medium 3.1 measured |
| LiveCodeBench (Vals AI) | Not measured | 44.8% | Only Mistral Medium 3.1 measured |
| Terminal-Bench 4 (Vals AI) | 65.2% | Not measured | Only Claude Opus 5.5 measured |
| Vibe Code Bench (Vals AI) | 90.3% | Not measured | Only Claude Opus 5.5 measured |
| Code migration (Vals AI) | 66.7% | Not measured | Only Claude Opus 5.5 measured |
| ProgramBench (Vals AI) | 18.5% | Not measured | Only Claude Opus 5.5 measured |
| IOI (Vals AI) | 95.1% | Not measured | Only Claude Opus 5.5 measured |
| Terminal-Bench 2.1 (Vals AI) | 87.6% | Not measured | Only Claude Opus 5.5 measured |
| SWE-bench Multimodal (Vals AI) | 70.2% | Not measured | Only Claude Opus 5.5 measured |
| Vibe Code Bench 1-100 (Vals AI) | 30.4% | Not measured | Only Claude Opus 5.5 measured |
| CyberBench (Vals AI) | 74.6% | Not measured | Only Claude Opus 5.5 measured |
| LiveCodeBench (Artificial Analysis run) | Not measured | 40.6% | Only Mistral Medium 3.1 measured |
| SciCode | 66.9% | 32.4% | Claude Opus 5.5 |
| Terminal-Bench Hard (Artificial Analysis run) | Not measured | 10.6% | Only Mistral Medium 3.1 measured |
| FrontierCode | 54.6% | Not measured | Only Claude Opus 5.5 measured |
| FrontierSWE | 62.3% | Not measured | Only Claude Opus 5.5 measured |
| MirrorCode | 77.4% | Not measured | Only Claude Opus 5.5 measured |
| ALE-Bench | 2147.4 | 210.2 | Claude Opus 5.5 |
| LMArena Text: coding | 1545 | 1433 | Claude Opus 5.5 |
| LMArena Text: software and IT | 1538 | 1436 | Claude Opus 5.5 |
| LMArena WebDev: React | 1855 | Not measured | Only Claude Opus 5.5 measured |
| LMArena WebDev: HTML | 1753 | Not measured | Only Claude Opus 5.5 measured |
| LMArena WebDev: from an image | 1753 | Not measured | Only Claude Opus 5.5 measured |
| SciCode | 18.5% | Not measured | Only Claude Opus 5.5 measured |
| Neither model has a result on the other 13 boards here | |||
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index10
| Benchmark | Claude Opus 5.5 | Mistral Medium 3.1 | Leader |
|---|---|---|---|
| AA Intelligence Index | 57.6 | 9.2 | Claude Opus 5.5 |
| Epoch Capabilities Index | 168.8 | Not measured | Only Claude Opus 5.5 measured |
Agentic workDirectional onlyPublic boards, shown as published, kept out of the index25 boards, none shared
| Benchmark | Claude Opus 5.5 | Mistral Medium 3.1 | Leader |
|---|---|---|---|
| AA Agentic Index | Not measured | 1.9 | Only Mistral Medium 3.1 measured |
| Design Arena: agents building web apps | 1317 | Not measured | Only Claude Opus 5.5 measured |
| Design Arena: agents building mobile apps | 1310 | Not measured | Only Claude Opus 5.5 measured |
| Design Arena: spreadsheets | 1352 | Not measured | Only Claude Opus 5.5 measured |
| LiveBench research | 85.0% | Not measured | Only Claude Opus 5.5 measured |
| LiveBench browser | 80.0% | Not measured | Only Claude Opus 5.5 measured |
| LiveBench long agentic | 85.0% | Not measured | Only Claude Opus 5.5 measured |
| SREBench (Vals AI) | 33.6% | Not measured | Only Claude Opus 5.5 measured |
| Finance Agent (Vals AI) | 58.6% | Not measured | Only Claude Opus 5.5 measured |
| Tax Agent Bench (Vals AI) | 45.6% | Not measured | Only Claude Opus 5.5 measured |
| Legal Research Bench (Vals AI) | 50.5% | Not measured | Only Claude Opus 5.5 measured |
| Harvey's Legal Agent Benchmark (Vals AI) | 9.2% | Not measured | Only Claude Opus 5.5 measured |
| Excel Modeling Benchmark (Vals AI) | 75.9% | Not measured | Only Claude Opus 5.5 measured |
| BioMysteryBench (Vals AI) | 79.3% | Not measured | Only Claude Opus 5.5 measured |
| Terminal-Bench-Science (Vals AI) | 47.1% | Not measured | Only Claude Opus 5.5 measured |
| Vals Science Index | 58.7% | Not measured | Only Claude Opus 5.5 measured |
| Time Horizon Index (Vals AI) | 91.3% | Not measured | Only Claude Opus 5.5 measured |
| CUA-bench (Vals AI) | 14.0% | Not measured | Only Claude Opus 5.5 measured |
| Robo-bench (Vals AI) | 14.6% | Not measured | Only Claude Opus 5.5 measured |
| τ²-Bench Telecom | Not measured | 40.6% | Only Mistral Medium 3.1 measured |
| APEX-Agents | 73.5% | Not measured | Only Claude Opus 5.5 measured |
| Remote Labor Index | 21.3% | Not measured | Only Claude Opus 5.5 measured |
| SpireClimb | 3.3% | Not measured | Only Claude Opus 5.5 measured |
| Vending-Bench 2 | $9,235 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Search | 1213 | Not measured | Only Claude Opus 5.5 measured |
| Neither model has a result on the other 16 boards here | |||
ReasoningLike-for-likePublic boards, shown as published, kept out of the index60
| Benchmark | Claude Opus 5.5 | Mistral Medium 3.1 | Leader |
|---|---|---|---|
| LiveBench reasoning | 92.2% | Not measured | Only Claude Opus 5.5 measured |
| MysteryMechanism (Vals AI) | 49.5% | Not measured | Only Claude Opus 5.5 measured |
| MMMU Pro (Vals AI) | Not measured | 63.0% | Only Mistral Medium 3.1 measured |
| GPQA Diamond (Artificial Analysis run) | Not measured | 58.8% | Only Mistral Medium 3.1 measured |
| Humanity's Last Exam (Artificial Analysis run) | 61.4% | 4.7% | Claude Opus 5.5 |
| GPQA Diamond (Epoch AI run) | 90.6% | Not measured | Only Claude Opus 5.5 measured |
| ARC-AGI | 98.5% | Not measured | Only Claude Opus 5.5 measured |
| ARC-AGI-2 | 93.3% | Not measured | Only Claude Opus 5.5 measured |
| Chess puzzles | 67.0% | Not measured | Only Claude Opus 5.5 measured |
| Mystery game puzzles | 71.0% | Not measured | Only Claude Opus 5.5 measured |
| EBR-bench | 71.4% | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: hard prompts | 1536 | 1426 | Claude Opus 5.5 |
| LMArena Text: expert | 1549 | 1408 | Claude Opus 5.5 |
| LMArena Text: hard prompts in English | 1535 | 1435 | Claude Opus 5.5 |
| LMArena Vision: diagrams | 1345 | 1175 | Claude Opus 5.5 |
| LMArena Vision: homework | 1362 | 1165 | Claude Opus 5.5 |
| Neither model has a result on the other 6 boards here | |||
MathLike-for-likePublic boards, shown as published, kept out of the index20
| Benchmark | Claude Opus 5.5 | Mistral Medium 3.1 | Leader |
|---|---|---|---|
| AIME | Not measured | 42.3% | Only Mistral Medium 3.1 measured |
| MATH 500 (Vals AI) | Not measured | 87.0% | Only Mistral Medium 3.1 measured |
| MGSM (Vals AI) | Not measured | 90.9% | Only Mistral Medium 3.1 measured |
| AA Math Index | Not measured | 38.3 | Only Mistral Medium 3.1 measured |
| AIME 2025 (Artificial Analysis run) | Not measured | 38.3% | Only Mistral Medium 3.1 measured |
| OTIS Mock AIME | 100.0% | Not measured | Only Claude Opus 5.5 measured |
| FrontierMath, tiers 1 to 3 | 91.2% | Not measured | Only Claude Opus 5.5 measured |
| FrontierMath, tier 4 | 95.0% | Not measured | Only Claude Opus 5.5 measured |
| ProofBench | 100.0% | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: math | 1518 | 1408 | Claude Opus 5.5 |
| LMArena Text: mathematical work | 1516 | 1412 | Claude Opus 5.5 |
| Neither model has a result on the other 2 boards here | |||
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index40
| Benchmark | Claude Opus 5.5 | Mistral Medium 3.1 | Leader |
|---|---|---|---|
| MMLU Pro | Not measured | 75.3% | Only Mistral Medium 3.1 measured |
| LegalBench (Vals AI) | Not measured | 62.0% | Only Mistral Medium 3.1 measured |
| CorpFin (Vals AI) | Not measured | 50.7% | Only Mistral Medium 3.1 measured |
| TaxEval (Vals AI) | Not measured | 70.3% | Only Mistral Medium 3.1 measured |
| MortgageTax (Vals AI) | Not measured | 36.5% | Only Mistral Medium 3.1 measured |
| MedQA (Vals AI) | Not measured | 78.2% | Only Mistral Medium 3.1 measured |
| MedCode (Vals AI) | 49.8% | Not measured | Only Claude Opus 5.5 measured |
| MMLU Pro (Artificial Analysis run) | Not measured | 68.3% | Only Mistral Medium 3.1 measured |
| SimpleQA Verified | 72.2% | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: science | 1524 | 1444 | Claude Opus 5.5 |
| LMArena Text: medicine and healthcare | 1509 | 1449 | Claude Opus 5.5 |
| LMArena Text: legal and government | 1518 | 1439 | Claude Opus 5.5 |
| LMArena Text: business and finance | 1494 | 1418 | Claude Opus 5.5 |
| FACTS Benchmark Suite | 65.3% | Not measured | Only Claude Opus 5.5 measured |
| Neither model has a result on the other 4 boards here | |||
Web designLike-for-likePublic boards, shown as published, kept out of the index70
| Benchmark | Claude Opus 5.5 | Mistral Medium 3.1 | Leader |
|---|---|---|---|
| Design Arena: websites | 1336 | 1133 | Claude Opus 5.5 |
| Design Arena: UI components | 1392 | 1100 | Claude Opus 5.5 |
| Design Arena: game dev | 1458 | 1074 | Claude Opus 5.5 |
| Design Arena: data viz | 1397 | 1144 | Claude Opus 5.5 |
| Design Arena: 3D | 1477 | 1081 | Claude Opus 5.5 |
| Design Arena: all code categories | 1390 | 1120 | Claude Opus 5.5 |
| Design Arena: SVG | 1333 | 993 | Claude Opus 5.5 |
| Design Arena: ASCII art | Not measured | 997 | Only Mistral Medium 3.1 measured |
| LiveBench design | 86.9% | Not measured | Only Claude Opus 5.5 measured |
GeneralLike-for-likePublic boards, shown as published, kept out of the index210
| Benchmark | Claude Opus 5.5 | Mistral Medium 3.1 | Leader |
|---|---|---|---|
| Vals Index | 70.2% | Not measured | Only Claude Opus 5.5 measured |
| LiveBench data analysis | 80.3% | Not measured | Only Claude Opus 5.5 measured |
| Public Benefits Bench (Vals AI) | 70.6% | Not measured | Only Claude Opus 5.5 measured |
| SAGE (Vals AI) | 45.8% | Not measured | Only Claude Opus 5.5 measured |
| MedScribe (Vals AI) | 91.4% | Not measured | Only Claude Opus 5.5 measured |
| IFBench | Not measured | 39.8% | Only Mistral Medium 3.1 measured |
| Long context reasoning (AA-LCR) | 84.7% | 42.7% | Claude Opus 5.5 |
| DTBench | 98.9% | 67.5% | Claude Opus 5.5 |
| LMCA | 68.2% | 19.1% | Claude Opus 5.5 |
| Furniture assembly | 83.3% | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text | 1516 | 1424 | Claude Opus 5.5 |
| LMArena Text: instruction following | 1537 | 1398 | Claude Opus 5.5 |
| LMArena Text: creative writing | 1535 | 1391 | Claude Opus 5.5 |
| LMArena Vision | 1321 | 1172 | Claude Opus 5.5 |
| LMArena Text: English | 1519 | 1438 | Claude Opus 5.5 |
| LMArena Text: non-English | 1507 | 1408 | Claude Opus 5.5 |
| LMArena Text: Chinese | 1582 | 1447 | Claude Opus 5.5 |
| LMArena Text: German | Not measured | 1432 | Only Mistral Medium 3.1 measured |
| LMArena Text: Japanese | 1534 | 1379 | Claude Opus 5.5 |
| LMArena Text: Korean | Not measured | 1380 | Only Mistral Medium 3.1 measured |
| LMArena Text: French | 1493 | 1460 | Claude Opus 5.5 |
| LMArena Text: Spanish | 1508 | 1433 | Claude Opus 5.5 |
| LMArena Text: Russian | 1517 | 1411 | Claude Opus 5.5 |
| LMArena Text: Polish | Not measured | 1430 | Only Mistral Medium 3.1 measured |
| LMArena Text: multi-turn | 1501 | 1418 | Claude Opus 5.5 |
| LMArena Text: longer queries | 1532 | 1406 | Claude Opus 5.5 |
| LMArena Text: writing and language | 1532 | 1395 | Claude Opus 5.5 |
| LMArena Text: entertainment and media | 1515 | 1390 | Claude Opus 5.5 |
| LMArena Vision: English | 1317 | 1179 | Claude Opus 5.5 |
| LMArena Vision: Chinese | Not measured | 1190 | Only Mistral Medium 3.1 measured |
| LMArena Vision: reading text | 1326 | 1175 | Claude Opus 5.5 |
| LMArena Vision: humor | Not measured | 1168 | Only Mistral Medium 3.1 measured |
| LMArena Vision: captioning | Not measured | 1145 | Only Mistral Medium 3.1 measured |
| LMArena Vision: recognizing things | Not measured | 1147 | Only Mistral Medium 3.1 measured |
| LMArena Vision: creative writing | 1320 | 1200 | Claude Opus 5.5 |
| Neither model has a result on the other 11 boards here | |||
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
| Benchmark | Claude Opus 5.5 | Mistral Medium 3.1 | Leader |
|---|---|---|---|
| Neither model has a result on 5 boards here | |||
What each workload costs
Three fixed token mixes at each model's listed price, so per-token rates become a bill.
Chat turn
1K input + 500 output tokens
Claude Opus 5.5$0.014Fits in one request
Mistral Medium 3.1$0.0014Fits in one request
Mistral Medium 3.1 costs less
Repository review
50K input + 3K output tokens
Claude Opus 5.5$0.260Fits in one request
Mistral Medium 3.1$0.026Fits in one request
Mistral Medium 3.1 costs less
Agent loop
200K input + 10K output tokens
Claude Opus 5.5$1.00Fits in one request
Mistral Medium 3.1$0.100Exceeds the context window
Mistral Medium 3.1 costs less
Listed OpenRouter rates, without cache or batch discounts. A workload that does not fit a model's context window would need splitting.
Specification differences
The leading value in a row is marked; a row with a missing value names no leader. Our two rows are marked in red.
| Specification | Anthropic Claude Opus 5.5 | Mistral Medium 3.1 |
|---|---|---|
| Maker | Anthropic | Mistral AI |
| Weights | No public weights listed | No public weights listed |
| Released | September 22, 2026 | August 13, 2025 |
| Context window | 1M | 131K |
| Input $/Mtok | $4.00 | $0.40 |
| Output $/Mtok | $20.00 | $2.00 |
| Coding index | 88.8 | Not benchmarked |
| Independent measurements behind it | 5 | 0 |
| Cost per solved task | Not computable | Not computable |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is Claude Opus 5.5 better than Mistral Medium 3.1 for coding?
Only Claude Opus 5.5 has a coding score, 88.8 on the Vibe Coding Index; Mistral Medium 3.1 has none, so the two cannot be ranked on coding. Pick Mistral Medium 3.1 for output tokens 10.0x cheaper ($2.00 vs $20.00 per million).
Which is cheaper, Claude Opus 5.5 or Mistral Medium 3.1?
Claude Opus 5.5 costs $4.00 per million input tokens and $20.00 per million output tokens; Mistral Medium 3.1 costs $0.40 and $2.00. Cost per solved task is known for neither of them.
Which has the bigger context window, Claude Opus 5.5 or Mistral Medium 3.1?
Claude Opus 5.5, with 1M tokens against 131K.
How many benchmarks is the Claude Opus 5.5 vs Mistral Medium 3.1 comparison based on?
45 benchmarks have a result for both models as of October 21, 2026. Claude Opus 5.5's coding index rests on 5 independent benchmarks and Mistral Medium 3.1's on 0. Where only one model has a result, the page says so instead of naming a winner.