Mistral Medium 3.1 vs o3
Updated October 21, 2026. 68 benchmarks have a result for both. Coding is ranked on the Vibe Coding Index; every other board is shown as published.
Decision reading
Neither model has a coding score yet, so the two cannot be ranked on coding.
Mistral Medium 3.1 has the edge where output tokens cost 4.0x less, and where what matters is LiveCodeBench (Vals AI) or LiveCodeBench (Artificial Analysis run), where it leads.
- Shared results
- 68
- Mistral Medium 3.1 only
- 6
- o3 only
- 29
- Like-for-like categories
- 8 of 9
Shared results can support a head-to-head reading. Results only one model has describe coverage, not superiority.
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
Neither has a coding score yet.
One side not measured
Intelligence
AA Intelligence Index
o3
o3 leads, 20.2 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
Reasoning
GPQA Diamond
No call
Only o3 has a GPQA Diamond result, 84.1%.
Directional only
Math
AIME
o3
o3 leads, 85.3% against 42.3%.
Same board, both measured
Knowledge
MMLU Pro
o3
o3 leads, 85.6% against 75.3%.
Same board, both measured
Web design
Design Arena: websites
Mistral Medium 3.1
Mistral Medium 3.1 leads, 1133 against 1036.
Same board, both measured
Long documents
Listed context window
o3
o3 takes 200K tokens against 131K.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
Mistral Medium 3.1
Mistral Medium 3.1 $0.0014, o3 $0.0060 per turn.
List prices
Cost per solved task
One SWE-bench Verified task, solved
No call
Only o3 has the number, $0.571.
Directional only
At a glance
- Coding index
- Mistral Medium 3.1 not benchmarked, o3 not benchmarked.
- Widest category
- Agentic work, 40.1 points apart on average over 1 shared benchmark.
- Widest single gap
- AA Math Index: Mistral Medium 3.1 38.3 against o3 88.3, 50.0 points apart on a 0 to 100 scale.
- Output price
- Mistral Medium 3.1 $2.00 against o3 $8.00 per million output tokens, 4.0x apart.
- Context window
- Mistral Medium 3.1 takes 131K tokens, o3 200K.
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 | Mistral Medium 3.1 | Bars | o3 | Ties |
|---|---|---|---|---|
| Coding | 2 | 4 | ||
| Intelligence | 0 | 1 | ||
| Agentic work | 0 | 1 | ||
| Reasoning | 3 | 5 | ||
| Math | 0 | 7 | ||
| Knowledge | 4 | 7 | ||
| Web design | 4 | 1 | ||
| General | 15 | 14 | ||
| All shared boards | 28 | 40 |
CodingLike-for-likeSix of these boards feed the Vibe Coding Index24
| Benchmark | Mistral Medium 3.1 | o3 | Leader |
|---|---|---|---|
| Aider polyglot | Not measured | 81.3% | Only o3 measured |
| SWE-bench Verified | Not measured | 58.4% | Only o3 measured |
| SWE-bench Multimodal | Not measured | 36.0% | Only o3 measured |
| AA Coding Index | 20.5 | Not measured | Only Mistral Medium 3.1 measured |
| LiveCodeBench (Vals AI) | 44.8% | 83.9% | o3 |
| LiveCodeBench (Artificial Analysis run) | 40.6% | 80.8% | o3 |
| SciCode | 32.4% | Not measured | Only Mistral Medium 3.1 measured |
| Terminal-Bench Hard (Artificial Analysis run) | 10.6% | 37.1% | o3 |
| GSO-Bench | Not measured | 8.8% | Only o3 measured |
| WeirdML | Not measured | 52.4% | Only o3 measured |
| ALE-Bench | 210.2 | 933.5 | o3 |
| LMArena Text: coding | 1433 | 1407 | Mistral Medium 3.1 |
| LMArena Text: software and IT | 1436 | 1415 | Mistral Medium 3.1 |
| Neither model has a result on the other 25 boards here | |||
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index01
| Benchmark | Mistral Medium 3.1 | o3 | Leader |
|---|---|---|---|
| AA Intelligence Index | 9.2 | 20.2 | o3 |
| Epoch Capabilities Index | Not measured | 146.7 | Only o3 measured |
Agentic workLike-for-likePublic boards, shown as published, kept out of the index01
| Benchmark | Mistral Medium 3.1 | o3 | Leader |
|---|---|---|---|
| AA Agentic Index | 1.9 | Not measured | Only Mistral Medium 3.1 measured |
| τ²-Bench Telecom | 40.6% | 80.7% | o3 |
| METR time horizons | Not measured | 65.4% | Only o3 measured |
| GDPval | Not measured | 30.8% | Only o3 measured |
| DeepResearch Bench | Not measured | 45.2% | Only o3 measured |
| OSWorld | Not measured | 23.0% | Only o3 measured |
| Neither model has a result on the other 33 boards here | |||
ReasoningLike-for-likePublic boards, shown as published, kept out of the index35
| Benchmark | Mistral Medium 3.1 | o3 | Leader |
|---|---|---|---|
| GPQA Diamond | Not measured | 84.1% | Only o3 measured |
| MMMU Pro (Vals AI) | 63.0% | 80.4% | o3 |
| GPQA Diamond (Artificial Analysis run) | 58.8% | 82.7% | o3 |
| Humanity's Last Exam (Artificial Analysis run) | 4.7% | 20.1% | o3 |
| GPQA Diamond (Epoch AI run) | Not measured | 81.8% | Only o3 measured |
| ARC-AGI | Not measured | 60.8% | Only o3 measured |
| ARC-AGI-2 | Not measured | 6.5% | Only o3 measured |
| SimpleBench | Not measured | 53.1% | Only o3 measured |
| Chess puzzles | Not measured | 37.0% | Only o3 measured |
| Mystery game puzzles | Not measured | 29.0% | Only o3 measured |
| VPCT | Not measured | 52.0% | Only o3 measured |
| LMArena Text: hard prompts | 1426 | 1402 | Mistral Medium 3.1 |
| LMArena Text: expert | 1408 | 1402 | Mistral Medium 3.1 |
| LMArena Text: hard prompts in English | 1435 | 1411 | Mistral Medium 3.1 |
| LMArena Vision: diagrams | 1175 | 1220 | o3 |
| LMArena Vision: homework | 1165 | 1234 | o3 |
| Neither model has a result on the other 5 boards here | |||
MathLike-for-likePublic boards, shown as published, kept out of the index07
| Benchmark | Mistral Medium 3.1 | o3 | Leader |
|---|---|---|---|
| AIME | 42.3% | 85.3% | o3 |
| MATH 500 (Vals AI) | 87.0% | 94.6% | o3 |
| MGSM (Vals AI) | 90.9% | 91.8% | o3 |
| AA Math Index | 38.3 | 88.3 | o3 |
| AIME 2025 (Artificial Analysis run) | 38.3% | 88.3% | o3 |
| OTIS Mock AIME | Not measured | 84.4% | Only o3 measured |
| FrontierMath, tiers 1 to 3 | Not measured | 33.3% | Only o3 measured |
| MATH level 5 | Not measured | 97.8% | Only o3 measured |
| LMArena Text: math | 1408 | 1426 | o3 |
| LMArena Text: mathematical work | 1412 | 1423 | o3 |
| Neither model has a result on the other 3 boards here | |||
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index47
| Benchmark | Mistral Medium 3.1 | o3 | Leader |
|---|---|---|---|
| MMLU Pro | 75.3% | 85.6% | o3 |
| LegalBench (Vals AI) | 62.0% | 83.8% | o3 |
| CorpFin (Vals AI) | 50.7% | 59.7% | o3 |
| TaxEval (Vals AI) | 70.3% | 74.6% | o3 |
| MortgageTax (Vals AI) | 36.5% | 65.7% | o3 |
| MedQA (Vals AI) | 78.2% | 96.1% | o3 |
| MedCode (Vals AI) | Not measured | 47.3% | Only o3 measured |
| MMLU Pro (Artificial Analysis run) | 68.3% | 85.3% | o3 |
| SimpleQA Verified | Not measured | 49.4% | Only o3 measured |
| GeoBench | Not measured | 74.0% | Only o3 measured |
| LMArena Text: science | 1444 | 1429 | Mistral Medium 3.1 |
| LMArena Text: medicine and healthcare | 1449 | 1448 | Mistral Medium 3.1 |
| LMArena Text: legal and government | 1439 | 1428 | Mistral Medium 3.1 |
| LMArena Text: business and finance | 1418 | 1393 | Mistral Medium 3.1 |
| Neither model has a result on the other 3 boards here | |||
Web designLike-for-likePublic boards, shown as published, kept out of the index41
| Benchmark | Mistral Medium 3.1 | o3 | Leader |
|---|---|---|---|
| Design Arena: websites | 1133 | 1036 | Mistral Medium 3.1 |
| Design Arena: UI components | 1099 | 1017 | Mistral Medium 3.1 |
| Design Arena: game dev | 1074 | 1034 | Mistral Medium 3.1 |
| Design Arena: data viz | 1144 | 1200 | o3 |
| Design Arena: 3D | 1081 | Not measured | Only Mistral Medium 3.1 measured |
| Design Arena: all code categories | 1120 | 1020 | Mistral Medium 3.1 |
| Design Arena: SVG | 993 | Not measured | Only Mistral Medium 3.1 measured |
| Design Arena: ASCII art | 997 | Not measured | Only Mistral Medium 3.1 measured |
| Neither model has a result on the other 1 board here | |||
GeneralLike-for-likePublic boards, shown as published, kept out of the index1514
| Benchmark | Mistral Medium 3.1 | o3 | Leader |
|---|---|---|---|
| SAGE (Vals AI) | Not measured | 41.8% | Only o3 measured |
| MedScribe (Vals AI) | Not measured | 76.7% | Only o3 measured |
| IFBench | 39.8% | 71.4% | o3 |
| Long context reasoning (AA-LCR) | 42.7% | 74.7% | o3 |
| DTBench | 67.5% | 84.8% | o3 |
| LMCA | 19.1% | 39.7% | o3 |
| Fiction.LiveBench | Not measured | 88.9% | Only o3 measured |
| Creative writing (Lech Mazur) | Not measured | 83.9% | Only o3 measured |
| CL-bench | Not measured | 17.8% | Only o3 measured |
| LMArena Text | 1424 | 1410 | Mistral Medium 3.1 |
| LMArena Text: instruction following | 1398 | 1368 | Mistral Medium 3.1 |
| LMArena Text: creative writing | 1391 | 1359 | Mistral Medium 3.1 |
| LMArena Vision | 1172 | 1214 | o3 |
| LMArena Text: English | 1438 | 1417 | Mistral Medium 3.1 |
| LMArena Text: non-English | 1408 | 1401 | Mistral Medium 3.1 |
| LMArena Text: Chinese | 1447 | 1437 | Mistral Medium 3.1 |
| LMArena Text: German | 1432 | 1420 | Mistral Medium 3.1 |
| LMArena Text: Japanese | 1379 | 1403 | o3 |
| LMArena Text: Korean | 1380 | 1370 | Mistral Medium 3.1 |
| LMArena Text: French | 1460 | 1430 | Mistral Medium 3.1 |
| LMArena Text: Spanish | 1433 | 1395 | Mistral Medium 3.1 |
| LMArena Text: Russian | 1411 | 1406 | Mistral Medium 3.1 |
| LMArena Text: Polish | 1430 | 1438 | o3 |
| LMArena Text: multi-turn | 1418 | 1405 | Mistral Medium 3.1 |
| LMArena Text: longer queries | 1406 | 1372 | Mistral Medium 3.1 |
| LMArena Text: writing and language | 1395 | 1372 | Mistral Medium 3.1 |
| LMArena Text: entertainment and media | 1390 | 1373 | Mistral Medium 3.1 |
| LMArena Vision: English | 1179 | 1221 | o3 |
| LMArena Vision: Chinese | 1190 | 1237 | o3 |
| LMArena Vision: reading text | 1175 | 1218 | o3 |
| LMArena Vision: humor | 1168 | 1222 | o3 |
| LMArena Vision: captioning | 1145 | 1210 | o3 |
| LMArena Vision: recognizing things | 1147 | 1234 | o3 |
| LMArena Vision: creative writing | 1200 | 1201 | o3 |
| Neither model has a result on the other 12 boards here | |||
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
| Benchmark | Mistral Medium 3.1 | o3 | 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
Mistral Medium 3.1 costs less
Repository review
50K input + 3K output tokens
Mistral Medium 3.1 costs less
Agent loop
200K input + 10K output tokens
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 | Mistral Medium 3.1 | OpenAI o3 |
|---|---|---|
| Maker | Mistral AI | OpenAI |
| Weights | No public weights listed | No public weights listed |
| Released | August 13, 2025 | April 16, 2025 |
| Context window | 131K | 200K |
| Input $/Mtok | $0.40 | $2.00 |
| Output $/Mtok | $2.00 | $8.00 |
| Coding index | Not benchmarked | Not benchmarked |
| Independent measurements behind it | 0 | 0 |
| Cost per solved task | Not computable | $0.571 |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is Mistral Medium 3.1 better than o3 for coding?
Neither model has a coding score yet, so the two cannot be ranked on coding. Mistral Medium 3.1 has the edge where output tokens cost 4.0x less, and where what matters is LiveCodeBench (Vals AI) or LiveCodeBench (Artificial Analysis run), where it leads.
Which is cheaper, Mistral Medium 3.1 or o3?
Mistral Medium 3.1 costs $0.40 per million input tokens and $2.00 per million output tokens; o3 costs $2.00 and $8.00. Cost per solved task is known for o3 only.
Which has the bigger context window, Mistral Medium 3.1 or o3?
o3, with 200K tokens against 131K.
How many benchmarks is the Mistral Medium 3.1 vs o3 comparison based on?
68 benchmarks have a result for both models as of October 21, 2026. Mistral Medium 3.1's coding index rests on 0 independent benchmarks and o3's on 0. Where only one model has a result, the page says so instead of naming a winner.