Kimi K3.1 Pro vs Mistral Medium 3.5
Kimi K3.1 Pro leads Mistral Medium 3.5 on coding, 82.2 to 25.4 on the Vibe Coding Index, and Mistral Medium 3.5 costs 1.3x less per output token ($7.50 vs $10.00 per million). Updated October 29, 2026; 18 benchmarks have a result for both.
Kimi K3.1 Pro or Mistral Medium 3.5: which to pick
Pick Kimi K3.1 Pro for coding: it scores 82.2 on the Vibe Coding Index against 25.4 for Mistral Medium 3.5.
Pick Mistral Medium 3.5 for output tokens 1.3x cheaper ($7.50 vs $10.00 per million).
- Shared results
- 18
- Kimi K3.1 Pro only
- 17
- Mistral Medium 3.5 only
- 63
- Like-for-like categories
- 6 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
Kimi K3.1 Pro
Kimi K3.1 Pro scores 82.2 against 25.4.
4 and 3 benchmarks behind the scores
Intelligence
AA Intelligence Index
No call
Only Kimi K3.1 Pro has a AA Intelligence Index result, 46.0.
Directional only
Agentic work
AA Agentic Index
No call
Only Mistral Medium 3.5 has a AA Agentic Index result, 7.0.
Directional only
Reasoning
GPQA Diamond
No call
Only Mistral Medium 3.5 has a GPQA Diamond result, 34.9%.
Directional only
Knowledge
MMLU Pro
No call
Only Mistral Medium 3.5 has a MMLU Pro result, 75.3%.
Directional only
Web design
Design Arena: websites
Kimi K3.1 Pro
Kimi K3.1 Pro leads, 1325 against 1141.
Same board, both measured
General
Vals Index
No call
Only Kimi K3.1 Pro has a Vals Index result, 62.5%.
Directional only
Long documents
Listed context window
Kimi K3.1 Pro
Kimi K3.1 Pro takes 1.05M tokens against 262K.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
Mistral Medium 3.5
Kimi K3.1 Pro $0.0070, Mistral Medium 3.5 $0.0053 per turn.
List prices
Cost per solved task
One SWE-bench Verified task, solved
No call
Only Mistral Medium 3.5 has the number, $6.02.
Directional only
At a glance
- Coding index
- Kimi K3.1 Pro 82.2 from 4 benchmarks, Mistral Medium 3.5 25.4 from 3 benchmarks.
- Widest category
- Math, 82.0 points apart on average over 1 shared benchmark.
- Widest single gap
- ProofBench: Kimi K3.1 Pro 91.0% against Mistral Medium 3.5 9.0%, 82.0 points apart on a 0 to 100 scale.
- Output price
- Kimi K3.1 Pro $10.00 against Mistral Medium 3.5 $7.50 per million output tokens, 1.3x apart.
- Context window
- Kimi K3.1 Pro takes 1.05M tokens, Mistral Medium 3.5 262K.
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 | Kimi K3.1 Pro | Bars | Mistral Medium 3.5 | Ties |
|---|---|---|---|---|
| Coding | 6 | 0 | ||
| Agentic work | 2 | 0 | ||
| Reasoning | 1 | 0 | ||
| Math | 1 | 0 | ||
| Web design | 7 | 0 | ||
| General | 1 | 0 | ||
| All shared boards | 18 | 0 |
CodingLike-for-likeSix of these boards feed the Vibe Coding Index60
| Benchmark | Kimi K3.1 Pro | Mistral Medium 3.5 | Leader |
|---|---|---|---|
| LiveBench coding | 81.8% | Not measured | Only Kimi K3.1 Pro measured |
| LMArena WebDev | 1695 | 1264 | Kimi K3.1 Pro |
| AA Coding Index | Not measured | 46.9 | Only Mistral Medium 3.5 measured |
| SWE-bench Verified (Vals AI) | Not measured | 66.4% | Only Mistral Medium 3.5 measured |
| Terminal-Bench 4 (Vals AI) | 63.6% | Not measured | Only Kimi K3.1 Pro measured |
| Vibe Code Bench (Vals AI) | 84.9% | 2.9% | Kimi K3.1 Pro |
| Code migration (Vals AI) | Not measured | 5.1% | Only Mistral Medium 3.5 measured |
| IOI (Vals AI) | 81.9% | Not measured | Only Kimi K3.1 Pro measured |
| Terminal-Bench 2.1 (Vals AI) | Not measured | 39.0% | Only Mistral Medium 3.5 measured |
| SciCode | 60.8% | 40.2% | Kimi K3.1 Pro |
| Terminal-Bench Hard (Artificial Analysis run) | Not measured | 33.3% | Only Mistral Medium 3.5 measured |
| ALE-Bench | 1932.8 | 764.0 | Kimi K3.1 Pro |
| LMArena Text: coding | Not measured | 1460 | Only Mistral Medium 3.5 measured |
| LMArena Text: software and IT | Not measured | 1458 | Only Mistral Medium 3.5 measured |
| LMArena WebDev: React | 1701 | 1254 | Kimi K3.1 Pro |
| LMArena WebDev: HTML | 1706 | 1308 | Kimi K3.1 Pro |
| Neither model has a result on the other 27 boards here | |||
IntelligenceDirectional onlyPublic boards, shown as published, kept out of the index2 boards, none shared
| Benchmark | Kimi K3.1 Pro | Mistral Medium 3.5 | Leader |
|---|---|---|---|
| AA Intelligence Index | 46.0 | Not measured | Only Kimi K3.1 Pro measured |
| Epoch Capabilities Index | Not measured | 141.4 | Only Mistral Medium 3.5 measured |
Agentic workLike-for-likePublic boards, shown as published, kept out of the index20
| Benchmark | Kimi K3.1 Pro | Mistral Medium 3.5 | Leader |
|---|---|---|---|
| AA Agentic Index | Not measured | 7.0 | Only Mistral Medium 3.5 measured |
| LiveBench research | 77.9% | Not measured | Only Kimi K3.1 Pro measured |
| LiveBench browser | 75.9% | Not measured | Only Kimi K3.1 Pro measured |
| LiveBench long agentic | 39.1% | Not measured | Only Kimi K3.1 Pro measured |
| Finance Agent (Vals AI) | Not measured | 32.1% | Only Mistral Medium 3.5 measured |
| Tax Agent Bench (Vals AI) | 24.9% | 4.5% | Kimi K3.1 Pro |
| Legal Research Bench (Vals AI) | 37.5% | 9.1% | Kimi K3.1 Pro |
| Harvey's Legal Agent Benchmark (Vals AI) | 11.7% | Not measured | Only Kimi K3.1 Pro measured |
| Excel Modeling Benchmark (Vals AI) | Not measured | 11.2% | Only Mistral Medium 3.5 measured |
| BioMysteryBench (Vals AI) | 75.6% | Not measured | Only Kimi K3.1 Pro measured |
| Terminal-Bench-Science (Vals AI) | 31.4% | Not measured | Only Kimi K3.1 Pro measured |
| Vals Science Index | 44.4% | Not measured | Only Kimi K3.1 Pro measured |
| τ²-Bench Telecom | Not measured | 94.2% | Only Mistral Medium 3.5 measured |
| Neither model has a result on the other 29 boards here | |||
ReasoningLike-for-likePublic boards, shown as published, kept out of the index10
| Benchmark | Kimi K3.1 Pro | Mistral Medium 3.5 | Leader |
|---|---|---|---|
| GPQA Diamond | Not measured | 34.9% | Only Mistral Medium 3.5 measured |
| LiveBench reasoning | 91.1% | Not measured | Only Kimi K3.1 Pro measured |
| MysteryMechanism (Vals AI) | 26.1% | Not measured | Only Kimi K3.1 Pro measured |
| GPQA Diamond (Artificial Analysis run) | Not measured | 74.8% | Only Mistral Medium 3.5 measured |
| Humanity's Last Exam (Artificial Analysis run) | 52.5% | 13.8% | Kimi K3.1 Pro |
| LMArena Text: hard prompts | Not measured | 1437 | Only Mistral Medium 3.5 measured |
| LMArena Text: expert | Not measured | 1432 | Only Mistral Medium 3.5 measured |
| LMArena Text: hard prompts in English | Not measured | 1445 | Only Mistral Medium 3.5 measured |
| LMArena Vision: diagrams | Not measured | 1254 | Only Mistral Medium 3.5 measured |
| LMArena Vision: homework | Not measured | 1230 | Only Mistral Medium 3.5 measured |
| Kagi LLM Benchmark | Not measured | 41.4% | Only Mistral Medium 3.5 measured |
| Neither model has a result on the other 12 boards here | |||
MathLike-for-likePublic boards, shown as published, kept out of the index10
| Benchmark | Kimi K3.1 Pro | Mistral Medium 3.5 | Leader |
|---|---|---|---|
| ProofBench | 91.0% | 9.0% | Kimi K3.1 Pro |
| LMArena Text: math | Not measured | 1432 | Only Mistral Medium 3.5 measured |
| LMArena Text: mathematical work | Not measured | 1441 | Only Mistral Medium 3.5 measured |
| MathArena | 59.6% | Not measured | Only Kimi K3.1 Pro measured |
| Neither model has a result on the other 10 boards here | |||
KnowledgeDirectional onlyPublic boards, shown as published, kept out of the index10 boards, none shared
| Benchmark | Kimi K3.1 Pro | Mistral Medium 3.5 | Leader |
|---|---|---|---|
| MMLU Pro | Not measured | 75.3% | Only Mistral Medium 3.5 measured |
| CaseLaw (Vals AI) | Not measured | 44.2% | Only Mistral Medium 3.5 measured |
| CorpFin (Vals AI) | Not measured | 58.8% | Only Mistral Medium 3.5 measured |
| TaxEval (Vals AI) | Not measured | 68.0% | Only Mistral Medium 3.5 measured |
| MortgageTax (Vals AI) | Not measured | 28.9% | Only Mistral Medium 3.5 measured |
| MedCode (Vals AI) | Not measured | 33.8% | Only Mistral Medium 3.5 measured |
| LMArena Text: science | Not measured | 1428 | Only Mistral Medium 3.5 measured |
| LMArena Text: medicine and healthcare | Not measured | 1409 | Only Mistral Medium 3.5 measured |
| LMArena Text: legal and government | Not measured | 1437 | Only Mistral Medium 3.5 measured |
| LMArena Text: business and finance | Not measured | 1426 | Only Mistral Medium 3.5 measured |
| Neither model has a result on the other 10 boards here | |||
Web designLike-for-likePublic boards, shown as published, kept out of the index70
| Benchmark | Kimi K3.1 Pro | Mistral Medium 3.5 | Leader |
|---|---|---|---|
| Design Arena: websites | 1325 | 1141 | Kimi K3.1 Pro |
| Design Arena: UI components | 1400 | 1074 | Kimi K3.1 Pro |
| Design Arena: game dev | 1410 | 1078 | Kimi K3.1 Pro |
| Design Arena: data viz | 1300 | 1121 | Kimi K3.1 Pro |
| Design Arena: 3D | 1451 | 1057 | Kimi K3.1 Pro |
| Design Arena: all code categories | 1354 | 1120 | Kimi K3.1 Pro |
| Design Arena: SVG | 1328 | 947 | Kimi K3.1 Pro |
| Design Arena: ASCII art | Not measured | 1060 | Only Mistral Medium 3.5 measured |
| LiveBench design | 77.8% | Not measured | Only Kimi K3.1 Pro measured |
GeneralLike-for-likePublic boards, shown as published, kept out of the index10
| Benchmark | Kimi K3.1 Pro | Mistral Medium 3.5 | Leader |
|---|---|---|---|
| Vals Index | 62.5% | Not measured | Only Kimi K3.1 Pro measured |
| LiveBench data analysis | 79.1% | Not measured | Only Kimi K3.1 Pro measured |
| SAGE (Vals AI) | Not measured | 72.0% | Only Mistral Medium 3.5 measured |
| MedScribe (Vals AI) | Not measured | 67.7% | Only Mistral Medium 3.5 measured |
| Vals Multimodal Index | Not measured | 34.8% | Only Mistral Medium 3.5 measured |
| IFBench | Not measured | 68.8% | Only Mistral Medium 3.5 measured |
| Long context reasoning (AA-LCR) | 86.3% | 69.3% | Kimi K3.1 Pro |
| DTBench | Not measured | 75.5% | Only Mistral Medium 3.5 measured |
| LMCA | Not measured | 26.1% | Only Mistral Medium 3.5 measured |
| Surface Evolver Bench | Not measured | 26.9% | Only Mistral Medium 3.5 measured |
| LMArena Text | Not measured | 1421 | Only Mistral Medium 3.5 measured |
| LMArena Text: instruction following | Not measured | 1415 | Only Mistral Medium 3.5 measured |
| LMArena Text: creative writing | Not measured | 1374 | Only Mistral Medium 3.5 measured |
| LMArena Vision | Not measured | 1222 | Only Mistral Medium 3.5 measured |
| LMArena Text: English | Not measured | 1433 | Only Mistral Medium 3.5 measured |
| LMArena Text: non-English | Not measured | 1405 | Only Mistral Medium 3.5 measured |
| LMArena Text: Chinese | Not measured | 1445 | Only Mistral Medium 3.5 measured |
| LMArena Text: German | Not measured | 1453 | Only Mistral Medium 3.5 measured |
| LMArena Text: Korean | Not measured | 1384 | Only Mistral Medium 3.5 measured |
| LMArena Text: French | Not measured | 1449 | Only Mistral Medium 3.5 measured |
| LMArena Text: Spanish | Not measured | 1411 | Only Mistral Medium 3.5 measured |
| LMArena Text: Russian | Not measured | 1396 | Only Mistral Medium 3.5 measured |
| LMArena Text: Polish | Not measured | 1430 | Only Mistral Medium 3.5 measured |
| LMArena Text: multi-turn | Not measured | 1423 | Only Mistral Medium 3.5 measured |
| LMArena Text: longer queries | Not measured | 1415 | Only Mistral Medium 3.5 measured |
| LMArena Text: writing and language | Not measured | 1384 | Only Mistral Medium 3.5 measured |
| LMArena Text: entertainment and media | Not measured | 1382 | Only Mistral Medium 3.5 measured |
| LMArena Vision: English | Not measured | 1240 | Only Mistral Medium 3.5 measured |
| LMArena Vision: Chinese | Not measured | 1244 | Only Mistral Medium 3.5 measured |
| LMArena Vision: reading text | Not measured | 1233 | Only Mistral Medium 3.5 measured |
| LMArena Vision: humor | Not measured | 1216 | Only Mistral Medium 3.5 measured |
| LMArena Vision: creative writing | Not measured | 1198 | Only Mistral Medium 3.5 measured |
| EQ-Bench 4 | Not measured | 983 | Only Mistral Medium 3.5 measured |
| Neither model has a result on the other 15 boards here | |||
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
| Benchmark | Kimi K3.1 Pro | Mistral Medium 3.5 | 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 3.5 costs less
Repository review
50K input + 3K output tokens
Mistral Medium 3.5 costs less
Agent loop
200K input + 10K output tokens
Mistral Medium 3.5 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 | MoonshotAI Kimi K3.1 Pro | Mistral Medium 3.5 |
|---|---|---|
| Maker | Moonshot AI | Mistral AI |
| Weights | No public weights listed | No public weights listed |
| Released | October 23, 2026 | April 30, 2026 |
| Context window | 1.05M | 262K |
| Input $/Mtok | $2.00 | $1.50 |
| Output $/Mtok | $10.00 | $7.50 |
| Coding index | 82.2 | 25.4 |
| Independent measurements behind it | 4 | 3 |
| Cost per solved task | Not computable | $6.02 |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is Kimi K3.1 Pro better than Mistral Medium 3.5 for coding?
Pick Kimi K3.1 Pro for coding: it scores 82.2 on the Vibe Coding Index against 25.4 for Mistral Medium 3.5. Pick Mistral Medium 3.5 for output tokens 1.3x cheaper ($7.50 vs $10.00 per million).
Which is cheaper, Kimi K3.1 Pro or Mistral Medium 3.5?
Kimi K3.1 Pro costs $2.00 per million input tokens and $10.00 per million output tokens; Mistral Medium 3.5 costs $1.50 and $7.50. Cost per solved task is known for Mistral Medium 3.5 only.
Which has the bigger context window, Kimi K3.1 Pro or Mistral Medium 3.5?
Kimi K3.1 Pro, with 1.05M tokens against 262K.
How many benchmarks is the Kimi K3.1 Pro vs Mistral Medium 3.5 comparison based on?
18 benchmarks have a result for both models as of October 29, 2026. Kimi K3.1 Pro's coding index rests on 4 independent benchmarks and Mistral Medium 3.5's on 3. Where only one model has a result, the page says so instead of naming a winner.