GPT-5.1-Codex vs Kimi K3
Kimi K3 leads GPT-5.1-Codex on coding, 62.3 to 15.3 on the Vibe Coding Index, and GPT-5.1-Codex costs 1.5x less per output token ($10.00 vs $15.00 per million). Updated October 21, 2026; 17 benchmarks have a result for both.
GPT-5.1-Codex or Kimi K3: which to pick
Pick Kimi K3 for coding: it scores 62.3 on the Vibe Coding Index against 15.3 for GPT-5.1-Codex.
Pick GPT-5.1-Codex for output tokens 1.5x cheaper ($10.00 vs $15.00 per million).
- Shared results
- 17
- GPT-5.1-Codex only
- 9
- Kimi K3 only
- 100
- 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
Kimi K3 scores 62.3 against 15.3.
2 and 6 benchmarks behind the scores
Intelligence
AA Intelligence Index
Kimi K3
Kimi K3 leads, 43.6 against 23.7.
Same board, both measured
Agentic work
AA Agentic Index
No call
Only Kimi K3 has a AA Agentic Index result, 50.0.
Directional only
Reasoning
GPQA Diamond
No call
Only Kimi K3 has a GPQA Diamond result, 92.9%.
Directional only
Knowledge
MMLU Pro
No call
Only Kimi K3 has a MMLU Pro result, 88.0%.
Directional only
Web design
Design Arena: websites
Kimi K3
Kimi K3 leads, 1335 against 1162.
Same board, both measured
General
Vals Index
No call
Only Kimi K3 has a Vals Index result, 53.0%.
Directional only
Long documents
Listed context window
Kimi K3
Kimi K3 takes 1.05M tokens against 400K.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
GPT-5.1-Codex
GPT-5.1-Codex $0.0063, Kimi K3 $0.011 per turn.
List prices
Cost per solved task
One SWE-bench Verified task, solved
Kimi K3
GPT-5.1-Codex $0.892, Kimi K3 $0.81.
Published attempt cost and pass rate
At a glance
- Coding index
- GPT-5.1-Codex 15.3 from 2 benchmarks, Kimi K3 62.3 from 6 benchmarks.
- Widest category
- Coding, 34.1 points apart on average over 5 shared benchmarks.
- Widest single gap
- Vibe Code Bench (Vals AI): GPT-5.1-Codex 13.1% against Kimi K3 85.0%, 71.8 points apart on a 0 to 100 scale.
- Output price
- GPT-5.1-Codex $10.00 against Kimi K3 $15.00 per million output tokens, 1.5x apart.
- Context window
- GPT-5.1-Codex takes 400K tokens, Kimi K3 1.05M.
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 | GPT-5.1-Codex | Bars | Kimi K3 | Ties |
|---|---|---|---|---|
| Coding | 0 | 5 | ||
| Intelligence | 0 | 1 | ||
| Agentic work | 0 | 3 | ||
| Reasoning | 0 | 2 | ||
| Web design | 0 | 5 | ||
| General | 0 | 1 | ||
| All shared boards | 0 | 17 |
CodingLike-for-likeSix of these boards feed the Vibe Coding Index05
| Benchmark | GPT-5.1-Codex | Kimi K3 | Leader |
|---|---|---|---|
| SWE-bench Verified | 66.0% | Not measured | Only GPT-5.1-Codex measured |
| LiveBench coding | Not measured | 59.3% | Only Kimi K3 measured |
| LMArena WebDev | 1337 | 1655 | Kimi K3 |
| AA Coding Index | Not measured | 76.2 | Only Kimi K3 measured |
| LiveCodeBench (Vals AI) | 85.5% | 87.2% | Kimi K3 |
| SWE-bench Verified (Vals AI) | Not measured | 93.4% | Only Kimi K3 measured |
| Terminal-Bench 4 (Vals AI) | Not measured | 17.2% | Only Kimi K3 measured |
| Vibe Code Bench (Vals AI) | 13.1% | 85.0% | Kimi K3 |
| Code migration (Vals AI) | Not measured | 16.1% | Only Kimi K3 measured |
| ProgramBench (Vals AI) | Not measured | 2.0% | Only Kimi K3 measured |
| IOI (Vals AI) | Not measured | 48.9% | Only Kimi K3 measured |
| Terminal-Bench 2.1 (Vals AI) | Not measured | 80.9% | Only Kimi K3 measured |
| SWE-bench Multimodal (Vals AI) | Not measured | 44.2% | Only Kimi K3 measured |
| Vibe Code Bench 1-100 (Vals AI) | Not measured | 18.2% | Only Kimi K3 measured |
| CyberBench (Vals AI) | Not measured | 75.2% | Only Kimi K3 measured |
| LiveCodeBench (Artificial Analysis run) | 84.9% | Not measured | Only GPT-5.1-Codex measured |
| SciCode | Not measured | 59.5% | Only Kimi K3 measured |
| Terminal-Bench Hard (Artificial Analysis run) | 34.8% | Not measured | Only GPT-5.1-Codex measured |
| Terminal-Bench | 57.8% | Not measured | Only GPT-5.1-Codex measured |
| FrontierCode | Not measured | 44.2% | Only Kimi K3 measured |
| FrontierSWE | Not measured | 25.9% | Only Kimi K3 measured |
| WeirdML | Not measured | 82.6% | Only Kimi K3 measured |
| ALE-Bench | 1244.9 | 1524.5 | Kimi K3 |
| LMArena Text: coding | Not measured | 1508 | Only Kimi K3 measured |
| LMArena Text: software and IT | Not measured | 1499 | Only Kimi K3 measured |
| LMArena WebDev: React | Not measured | 1670 | Only Kimi K3 measured |
| LMArena WebDev: HTML | 1346 | 1644 | Kimi K3 |
| LMArena WebDev: from an image | Not measured | 1579 | Only Kimi K3 measured |
| Neither model has a result on the other 11 boards here | |||
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index01
| Benchmark | GPT-5.1-Codex | Kimi K3 | Leader |
|---|---|---|---|
| AA Intelligence Index | 23.7 | 43.6 | Kimi K3 |
| Epoch Capabilities Index | Not measured | 157.9 | Only Kimi K3 measured |
Agentic workLike-for-likePublic boards, shown as published, kept out of the index03
| Benchmark | GPT-5.1-Codex | Kimi K3 | Leader |
|---|---|---|---|
| AA Agentic Index | Not measured | 50.0 | Only Kimi K3 measured |
| Design Arena: agents building web apps | 1018 | 1295 | Kimi K3 |
| Design Arena: agents building full-stack apps | 1086 | 1315 | Kimi K3 |
| Design Arena: agents building mobile apps | 1191 | 1269 | Kimi K3 |
| Design Arena: agents building Android apps | Not measured | 1250 | Only Kimi K3 measured |
| Design Arena: agents building Godot games | Not measured | 1223 | Only Kimi K3 measured |
| Design Arena: agents building games | Not measured | 1252 | Only Kimi K3 measured |
| Design Arena: HTML slides | Not measured | 1256 | Only Kimi K3 measured |
| Design Arena: PowerPoint slides | Not measured | 1273 | Only Kimi K3 measured |
| Design Arena: spreadsheets | Not measured | 1058 | Only Kimi K3 measured |
| LiveBench research | Not measured | 79.0% | Only Kimi K3 measured |
| LiveBench browser | Not measured | 16.0% | Only Kimi K3 measured |
| LiveBench long agentic | Not measured | 42.8% | Only Kimi K3 measured |
| Finance Agent (Vals AI) | Not measured | 53.1% | Only Kimi K3 measured |
| Tax Agent Bench (Vals AI) | Not measured | 33.4% | Only Kimi K3 measured |
| Legal Research Bench (Vals AI) | Not measured | 46.1% | Only Kimi K3 measured |
| Harvey's Legal Agent Benchmark (Vals AI) | Not measured | 12.9% | Only Kimi K3 measured |
| Excel Modeling Benchmark (Vals AI) | Not measured | 66.7% | Only Kimi K3 measured |
| BioMysteryBench (Vals AI) | Not measured | 72.6% | Only Kimi K3 measured |
| Terminal-Bench-Science (Vals AI) | Not measured | 1.4% | Only Kimi K3 measured |
| Time Horizon Index (Vals AI) | Not measured | 10.5% | Only Kimi K3 measured |
| τ²-Bench Telecom | 83.0% | Not measured | Only GPT-5.1-Codex measured |
| APEX-Agents | Not measured | 47.8% | Only Kimi K3 measured |
| PostTrainBench | Not measured | 32.0% | Only Kimi K3 measured |
| Vending-Bench 2 | Not measured | $5,165 | Only Kimi K3 measured |
| Neither model has a result on the other 16 boards here | |||
ReasoningLike-for-likePublic boards, shown as published, kept out of the index02
| Benchmark | GPT-5.1-Codex | Kimi K3 | Leader |
|---|---|---|---|
| GPQA Diamond | Not measured | 92.9% | Only Kimi K3 measured |
| LiveBench reasoning | Not measured | 90.7% | Only Kimi K3 measured |
| MMMU Pro (Vals AI) | Not measured | 88.2% | Only Kimi K3 measured |
| GPQA Diamond (Artificial Analysis run) | 86.0% | 93.5% | Kimi K3 |
| Humanity's Last Exam (Artificial Analysis run) | 25.7% | 46.9% | Kimi K3 |
| GPQA Diamond (Epoch AI run) | Not measured | 93.1% | Only Kimi K3 measured |
| ARC-AGI | Not measured | 94.5% | Only Kimi K3 measured |
| ARC-AGI-2 | Not measured | 60.4% | Only Kimi K3 measured |
| SimpleBench | Not measured | 60.7% | Only Kimi K3 measured |
| Chess puzzles | Not measured | 37.0% | Only Kimi K3 measured |
| Mystery game puzzles | Not measured | 26.0% | Only Kimi K3 measured |
| LMArena Text: hard prompts | Not measured | 1495 | Only Kimi K3 measured |
| LMArena Text: expert | Not measured | 1520 | Only Kimi K3 measured |
| LMArena Text: hard prompts in English | Not measured | 1496 | Only Kimi K3 measured |
| Neither model has a result on the other 8 boards here | |||
MathDirectional onlyPublic boards, shown as published, kept out of the index8 boards, none shared
| Benchmark | GPT-5.1-Codex | Kimi K3 | Leader |
|---|---|---|---|
| AA Math Index | 95.7 | Not measured | Only GPT-5.1-Codex measured |
| AIME 2025 (Artificial Analysis run) | 95.7% | Not measured | Only GPT-5.1-Codex measured |
| OTIS Mock AIME | Not measured | 97.2% | Only Kimi K3 measured |
| FrontierMath, tiers 1 to 3 | Not measured | 72.2% | Only Kimi K3 measured |
| FrontierMath, tier 4 | Not measured | 39.0% | Only Kimi K3 measured |
| ProofBench | Not measured | 87.0% | Only Kimi K3 measured |
| LMArena Text: math | Not measured | 1494 | Only Kimi K3 measured |
| LMArena Text: mathematical work | Not measured | 1505 | Only Kimi K3 measured |
| Neither model has a result on the other 5 boards here | |||
KnowledgeDirectional onlyPublic boards, shown as published, kept out of the index12 boards, none shared
| Benchmark | GPT-5.1-Codex | Kimi K3 | Leader |
|---|---|---|---|
| MMLU Pro | Not measured | 88.0% | Only Kimi K3 measured |
| LegalBench (Vals AI) | Not measured | 86.2% | Only Kimi K3 measured |
| CorpFin (Vals AI) | Not measured | 71.6% | Only Kimi K3 measured |
| TaxEval (Vals AI) | Not measured | 75.7% | Only Kimi K3 measured |
| MortgageTax (Vals AI) | Not measured | 66.3% | Only Kimi K3 measured |
| MedCode (Vals AI) | Not measured | 49.4% | Only Kimi K3 measured |
| MMLU Pro (Artificial Analysis run) | 86.0% | Not measured | Only GPT-5.1-Codex measured |
| SimpleQA Verified | Not measured | 50.6% | Only Kimi K3 measured |
| LMArena Text: science | Not measured | 1508 | Only Kimi K3 measured |
| LMArena Text: medicine and healthcare | Not measured | 1489 | Only Kimi K3 measured |
| LMArena Text: legal and government | Not measured | 1503 | Only Kimi K3 measured |
| LMArena Text: business and finance | Not measured | 1470 | Only Kimi K3 measured |
| Neither model has a result on the other 6 boards here | |||
Web designLike-for-likePublic boards, shown as published, kept out of the index05
| Benchmark | GPT-5.1-Codex | Kimi K3 | Leader |
|---|---|---|---|
| Design Arena: websites | 1162 | 1335 | Kimi K3 |
| Design Arena: UI components | 1237 | 1344 | Kimi K3 |
| Design Arena: game dev | 1138 | 1359 | Kimi K3 |
| Design Arena: data viz | 1213 | 1351 | Kimi K3 |
| Design Arena: 3D | Not measured | 1388 | Only Kimi K3 measured |
| Design Arena: all code categories | 1152 | 1360 | Kimi K3 |
| Design Arena: SVG | Not measured | 1302 | Only Kimi K3 measured |
| LiveBench design | Not measured | 77.2% | Only Kimi K3 measured |
| Neither model has a result on the other 1 board here | |||
GeneralLike-for-likePublic boards, shown as published, kept out of the index01
| Benchmark | GPT-5.1-Codex | Kimi K3 | Leader |
|---|---|---|---|
| Vals Index | Not measured | 53.0% | Only Kimi K3 measured |
| LiveBench data analysis | Not measured | 78.7% | Only Kimi K3 measured |
| Public Benefits Bench (Vals AI) | Not measured | 68.2% | Only Kimi K3 measured |
| SAGE (Vals AI) | Not measured | 52.8% | Only Kimi K3 measured |
| MedScribe (Vals AI) | Not measured | 88.0% | Only Kimi K3 measured |
| Vals Multimodal Index | Not measured | 73.4% | Only Kimi K3 measured |
| IFBench | 70.0% | Not measured | Only GPT-5.1-Codex measured |
| Long context reasoning (AA-LCR) | 69.3% | 88.7% | Kimi K3 |
| DTBench | Not measured | 91.2% | Only Kimi K3 measured |
| LMCA | Not measured | 52.7% | Only Kimi K3 measured |
| Surface Evolver Bench | Not measured | 95.0% | Only Kimi K3 measured |
| Furniture assembly | Not measured | 34.2% | Only Kimi K3 measured |
| LMArena Text | Not measured | 1476 | Only Kimi K3 measured |
| LMArena Text: instruction following | Not measured | 1485 | Only Kimi K3 measured |
| LMArena Text: creative writing | Not measured | 1457 | Only Kimi K3 measured |
| LMArena Text: English | Not measured | 1481 | Only Kimi K3 measured |
| LMArena Text: non-English | Not measured | 1466 | Only Kimi K3 measured |
| LMArena Text: Chinese | Not measured | 1529 | Only Kimi K3 measured |
| LMArena Text: German | Not measured | 1490 | Only Kimi K3 measured |
| LMArena Text: Japanese | Not measured | 1494 | Only Kimi K3 measured |
| LMArena Text: Korean | Not measured | 1460 | Only Kimi K3 measured |
| LMArena Text: French | Not measured | 1492 | Only Kimi K3 measured |
| LMArena Text: Spanish | Not measured | 1472 | Only Kimi K3 measured |
| LMArena Text: Russian | Not measured | 1485 | Only Kimi K3 measured |
| LMArena Text: Polish | Not measured | 1458 | Only Kimi K3 measured |
| LMArena Text: multi-turn | Not measured | 1489 | Only Kimi K3 measured |
| LMArena Text: longer queries | Not measured | 1494 | Only Kimi K3 measured |
| LMArena Text: writing and language | Not measured | 1471 | Only Kimi K3 measured |
| LMArena Text: entertainment and media | Not measured | 1453 | Only Kimi K3 measured |
| Neither model has a result on the other 17 boards here | |||
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
| Benchmark | GPT-5.1-Codex | Kimi K3 | 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
GPT-5.1-Codex costs less
Repository review
50K input + 3K output tokens
GPT-5.1-Codex costs less
Agent loop
200K input + 10K output tokens
GPT-5.1-Codex 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 | OpenAI GPT-5.1-Codex | MoonshotAI Kimi K3 |
|---|---|---|
| Maker | OpenAI | Moonshot AI |
| Weights | No public weights listed | Open weights |
| Released | November 13, 2025 | July 16, 2026 |
| Context window | 400K | 1.05M |
| Input $/Mtok | $1.25 | $3.00 |
| Output $/Mtok | $10.00 | $15.00 |
| Coding index | 15.3 | 62.3 |
| Independent measurements behind it | 2 | 6 |
| Cost per solved task | $0.892 | $0.81 |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is GPT-5.1-Codex better than Kimi K3 for coding?
Pick Kimi K3 for coding: it scores 62.3 on the Vibe Coding Index against 15.3 for GPT-5.1-Codex. Pick GPT-5.1-Codex for output tokens 1.5x cheaper ($10.00 vs $15.00 per million).
Which is cheaper, GPT-5.1-Codex or Kimi K3?
GPT-5.1-Codex costs $1.25 per million input tokens and $10.00 per million output tokens; Kimi K3 costs $3.00 and $15.00. Per solved SWE-bench Verified task, GPT-5.1-Codex costs $0.892 and Kimi K3 $0.81.
Which has the bigger context window, GPT-5.1-Codex or Kimi K3?
Kimi K3, with 1.05M tokens against 400K.
How many benchmarks is the GPT-5.1-Codex vs Kimi K3 comparison based on?
17 benchmarks have a result for both models as of October 21, 2026. GPT-5.1-Codex's coding index rests on 2 independent benchmarks and Kimi K3's on 6. Where only one model has a result, the page says so instead of naming a winner.