GPT-5 Nano vs Kimi K2 Thinking
Updated October 21, 2026. 25 benchmarks have a result for both. Coding is ranked on the Vibe Coding Index; every other board is shown as published.
Decision reading
Pick Kimi K2 Thinking for coding: it scores 63.4 on the Vibe Coding Index against 34.8 for GPT-5 Nano.
Pick GPT-5 Nano when output tokens cost 6.3x less, or when a solved task costs $0.109 against $0.61.
- Shared results
- 25
- GPT-5 Nano only
- 60
- Kimi K2 Thinking only
- 5
- 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, four public coding benchmarks
Kimi K2 Thinking
Kimi K2 Thinking scores 63.4 against 34.8.
One benchmark behind each score
Intelligence
AA Intelligence Index
Kimi K2 Thinking
Kimi K2 Thinking leads, 22.0 against 13.0.
Same board, both measured
Reasoning
GPQA Diamond
Kimi K2 Thinking
Kimi K2 Thinking leads, 78.5% against 63.4%.
Same board, both measured
Math
AIME
Kimi K2 Thinking
Kimi K2 Thinking leads, 85.4% against 81.2%.
Same board, both measured
Knowledge
MMLU Pro
Kimi K2 Thinking
Kimi K2 Thinking leads, 81.1% against 76.1%.
Same board, both measured
Web design
Design Arena: websites
Kimi K2 Thinking
Kimi K2 Thinking leads, 1113 against 1101.
Same board, both measured
Long documents
Listed context window
GPT-5 Nano
GPT-5 Nano takes 400K tokens against 262K.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
GPT-5 Nano
GPT-5 Nano $0.0003, Kimi K2 Thinking $0.0019 per turn.
List prices
Cost per solved task
One SWE-bench Verified task, solved
GPT-5 Nano
GPT-5 Nano $0.109, Kimi K2 Thinking $0.61.
Published attempt cost and pass rate
At a glance
- Coding index
- GPT-5 Nano 34.8 from 1 benchmark, Kimi K2 Thinking 63.4 from 1 benchmark.
- Widest category
- Agentic work, 56.4 points apart on average over 1 shared benchmark.
- Widest single gap
- τ²-Bench Telecom: GPT-5 Nano 36.5% against Kimi K2 Thinking 93.0%, 56.4 points apart on a 0 to 100 scale.
- Output price
- GPT-5 Nano $0.40 against Kimi K2 Thinking $2.50 per million output tokens, 6.3x apart.
- Context window
- GPT-5 Nano takes 400K tokens, Kimi K2 Thinking 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 | GPT-5 Nano | Bars | Kimi K2 Thinking | Ties |
|---|---|---|---|---|
| Coding | 1 | 5 | ||
| Intelligence | 0 | 2 | ||
| Agentic work | 0 | 1 | ||
| Reasoning | 0 | 3 | ||
| Math | 0 | 4 | ||
| Knowledge | 1 | 5 | ||
| Web design | 0 | 1 | ||
| General | 0 | 2 | ||
| All shared boards | 2 | 23 |
CodingLike-for-likeFour of these boards feed the Vibe Coding Index15
| Benchmark | GPT-5 Nano | Kimi K2 Thinking | Leader |
|---|---|---|---|
| SWE-bench Verified | 34.8% | 63.4% | Kimi K2 Thinking |
| LiveCodeBench (Vals AI) | 70.2% | 63.1% | GPT-5 Nano |
| SWE-bench Verified (Vals AI) | Not measured | 60.2% | Only Kimi K2 Thinking measured |
| LiveCodeBench (Artificial Analysis run) | 78.9% | 85.3% | Kimi K2 Thinking |
| Terminal-Bench Hard (Artificial Analysis run) | 17.4% | 31.1% | Kimi K2 Thinking |
| Terminal-Bench | 21.8% | 35.7% | Kimi K2 Thinking |
| WeirdML | 38.1% | 42.8% | Kimi K2 Thinking |
| ALE-Bench | Not measured | 597.5 | Only Kimi K2 Thinking measured |
| LMArena Text: coding | 1351 | Not measured | Only GPT-5 Nano measured |
| LMArena Text: software and IT | 1345 | Not measured | Only GPT-5 Nano measured |
| Neither model has a result on the other 28 boards here | |||
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index02
| Benchmark | GPT-5 Nano | Kimi K2 Thinking | Leader |
|---|---|---|---|
| AA Intelligence Index | 13.0 | 22.0 | Kimi K2 Thinking |
| Epoch Capabilities Index | 139.2 | 145.8 | Kimi K2 Thinking |
Agentic workLike-for-likePublic boards, shown as published, kept out of the index01
| Benchmark | GPT-5 Nano | Kimi K2 Thinking | Leader |
|---|---|---|---|
| τ²-Bench Telecom | 36.5% | 93.0% | Kimi K2 Thinking |
| METR time horizons | Not measured | 59.2% | Only Kimi K2 Thinking measured |
| Neither model has a result on the other 37 boards here | |||
ReasoningLike-for-likePublic boards, shown as published, kept out of the index03
| Benchmark | GPT-5 Nano | Kimi K2 Thinking | Leader |
|---|---|---|---|
| GPQA Diamond | 63.4% | 78.5% | Kimi K2 Thinking |
| MMMU Pro (Vals AI) | 70.9% | Not measured | Only GPT-5 Nano measured |
| GPQA Diamond (Artificial Analysis run) | 67.6% | 83.8% | Kimi K2 Thinking |
| Humanity's Last Exam (Artificial Analysis run) | 9.5% | 23.8% | Kimi K2 Thinking |
| GPQA Diamond (Epoch AI run) | 69.4% | Not measured | Only GPT-5 Nano measured |
| ARC-AGI | 20.7% | Not measured | Only GPT-5 Nano measured |
| ARC-AGI-2 | 2.6% | Not measured | Only GPT-5 Nano measured |
| Chess puzzles | 22.0% | Not measured | Only GPT-5 Nano measured |
| Mystery game puzzles | 9.0% | Not measured | Only GPT-5 Nano measured |
| VPCT | 37.2% | Not measured | Only GPT-5 Nano measured |
| LMArena Text: hard prompts | 1328 | Not measured | Only GPT-5 Nano measured |
| LMArena Text: expert | 1321 | Not measured | Only GPT-5 Nano measured |
| LMArena Text: hard prompts in English | 1338 | Not measured | Only GPT-5 Nano measured |
| LMArena Vision: diagrams | 1141 | Not measured | Only GPT-5 Nano measured |
| LMArena Vision: homework | 1157 | Not measured | Only GPT-5 Nano measured |
| Neither model has a result on the other 6 boards here | |||
MathLike-for-likePublic boards, shown as published, kept out of the index04
| Benchmark | GPT-5 Nano | Kimi K2 Thinking | Leader |
|---|---|---|---|
| AIME | 81.2% | 85.4% | Kimi K2 Thinking |
| MATH 500 (Vals AI) | 93.8% | Not measured | Only GPT-5 Nano measured |
| MGSM (Vals AI) | 89.3% | 90.2% | Kimi K2 Thinking |
| AA Math Index | 83.7 | 94.7 | Kimi K2 Thinking |
| AIME 2025 (Artificial Analysis run) | 83.7% | 94.7% | Kimi K2 Thinking |
| OTIS Mock AIME | 81.1% | Not measured | Only GPT-5 Nano measured |
| FrontierMath, tiers 1 to 3 | 20.0% | Not measured | Only GPT-5 Nano measured |
| FrontierMath, tier 4 | 2.4% | Not measured | Only GPT-5 Nano measured |
| ProofBench | 12.0% | Not measured | Only GPT-5 Nano measured |
| MATH level 5 | 95.2% | Not measured | Only GPT-5 Nano measured |
| LMArena Text: math | 1317 | Not measured | Only GPT-5 Nano measured |
| LMArena Text: mathematical work | 1326 | Not measured | Only GPT-5 Nano measured |
| Neither model has a result on the other 1 board here | |||
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index15
| Benchmark | GPT-5 Nano | Kimi K2 Thinking | Leader |
|---|---|---|---|
| MMLU Pro | 76.1% | 81.1% | Kimi K2 Thinking |
| LegalBench (Vals AI) | 50.1% | 80.2% | Kimi K2 Thinking |
| CaseLaw (Vals AI) | 52.6% | 65.7% | Kimi K2 Thinking |
| CorpFin (Vals AI) | Not measured | 60.6% | Only Kimi K2 Thinking measured |
| TaxEval (Vals AI) | 67.4% | 71.7% | Kimi K2 Thinking |
| MortgageTax (Vals AI) | 53.6% | Not measured | Only GPT-5 Nano measured |
| MedQA (Vals AI) | 93.3% | 92.6% | GPT-5 Nano |
| MedCode (Vals AI) | 30.4% | Not measured | Only GPT-5 Nano measured |
| MMLU Pro (Artificial Analysis run) | 78.0% | 84.8% | Kimi K2 Thinking |
| SimpleQA Verified | 11.7% | Not measured | Only GPT-5 Nano measured |
| LMArena Text: science | 1318 | Not measured | Only GPT-5 Nano measured |
| LMArena Text: medicine and healthcare | 1335 | Not measured | Only GPT-5 Nano measured |
| LMArena Text: legal and government | 1298 | Not measured | Only GPT-5 Nano measured |
| LMArena Text: business and finance | 1311 | Not measured | Only GPT-5 Nano measured |
| Neither model has a result on the other 3 boards here | |||
Web designLike-for-likePublic boards, shown as published, kept out of the index01
| Benchmark | GPT-5 Nano | Kimi K2 Thinking | Leader |
|---|---|---|---|
| Design Arena: websites | 1101 | 1113 | Kimi K2 Thinking |
| Design Arena: UI components | 1066 | Not measured | Only GPT-5 Nano measured |
| Design Arena: game dev | 1045 | Not measured | Only GPT-5 Nano measured |
| Design Arena: data viz | 1056 | Not measured | Only GPT-5 Nano measured |
| Design Arena: 3D | 966 | Not measured | Only GPT-5 Nano measured |
| Design Arena: all code categories | 1084 | Not measured | Only GPT-5 Nano measured |
| Neither model has a result on the other 3 boards here | |||
GeneralLike-for-likePublic boards, shown as published, kept out of the index02
| Benchmark | GPT-5 Nano | Kimi K2 Thinking | Leader |
|---|---|---|---|
| SAGE (Vals AI) | 30.4% | Not measured | Only GPT-5 Nano measured |
| MedScribe (Vals AI) | 72.9% | Not measured | Only GPT-5 Nano measured |
| IFBench | 67.6% | 68.1% | Kimi K2 Thinking |
| Long context reasoning (AA-LCR) | 45.0% | 72.0% | Kimi K2 Thinking |
| DTBench | 62.7% | Not measured | Only GPT-5 Nano measured |
| LMCA | 7.9% | Not measured | Only GPT-5 Nano measured |
| Fiction.LiveBench | 44.4% | Not measured | Only GPT-5 Nano measured |
| CL-bench | Not measured | 17.6% | Only Kimi K2 Thinking measured |
| LMArena Text | 1320 | Not measured | Only GPT-5 Nano measured |
| LMArena Text: instruction following | 1306 | Not measured | Only GPT-5 Nano measured |
| LMArena Text: creative writing | 1249 | Not measured | Only GPT-5 Nano measured |
| LMArena Vision | 1159 | Not measured | Only GPT-5 Nano measured |
| LMArena Text: English | 1321 | Not measured | Only GPT-5 Nano measured |
| LMArena Text: non-English | 1313 | Not measured | Only GPT-5 Nano measured |
| LMArena Text: Chinese | 1356 | Not measured | Only GPT-5 Nano measured |
| LMArena Text: German | 1327 | Not measured | Only GPT-5 Nano measured |
| LMArena Text: Japanese | 1227 | Not measured | Only GPT-5 Nano measured |
| LMArena Text: Korean | 1269 | Not measured | Only GPT-5 Nano measured |
| LMArena Text: Spanish | 1360 | Not measured | Only GPT-5 Nano measured |
| LMArena Text: Russian | 1296 | Not measured | Only GPT-5 Nano measured |
| LMArena Text: Polish | 1314 | Not measured | Only GPT-5 Nano measured |
| LMArena Text: multi-turn | 1311 | Not measured | Only GPT-5 Nano measured |
| LMArena Text: longer queries | 1312 | Not measured | Only GPT-5 Nano measured |
| LMArena Text: writing and language | 1283 | Not measured | Only GPT-5 Nano measured |
| LMArena Text: entertainment and media | 1268 | Not measured | Only GPT-5 Nano measured |
| LMArena Vision: English | 1170 | Not measured | Only GPT-5 Nano measured |
| LMArena Vision: Chinese | 1176 | Not measured | Only GPT-5 Nano measured |
| LMArena Vision: reading text | 1152 | Not measured | Only GPT-5 Nano measured |
| LMArena Vision: humor | 1110 | Not measured | Only GPT-5 Nano 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 Nano | Kimi K2 Thinking | 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 Nano costs less
Repository review
50K input + 3K output tokens
GPT-5 Nano costs less
Agent loop
200K input + 10K output tokens
GPT-5 Nano 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 Nano | MoonshotAI Kimi K2 Thinking |
|---|---|---|
| Maker | OpenAI | Moonshot AI |
| Weights | No public weights listed | Open weights |
| Released | August 7, 2025 | November 6, 2025 |
| Context window | 400K | 262K |
| Input $/Mtok | $0.05 | $0.60 |
| Output $/Mtok | $0.40 | $2.50 |
| Coding index | 34.8 | 63.4 |
| Independent measurements behind it | 1 | 1 |
| Cost per solved task | $0.109 | $0.61 |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is GPT-5 Nano better than Kimi K2 Thinking for coding?
Pick Kimi K2 Thinking for coding: it scores 63.4 on the Vibe Coding Index against 34.8 for GPT-5 Nano. Pick GPT-5 Nano when output tokens cost 6.3x less, or when a solved task costs $0.109 against $0.61.
Which is cheaper, GPT-5 Nano or Kimi K2 Thinking?
GPT-5 Nano costs $0.05 per million input tokens and $0.40 per million output tokens; Kimi K2 Thinking costs $0.60 and $2.50. Per solved SWE-bench Verified task, GPT-5 Nano costs $0.109 and Kimi K2 Thinking $0.61.
Which has the bigger context window, GPT-5 Nano or Kimi K2 Thinking?
GPT-5 Nano, with 400K tokens against 262K.
How many benchmarks is the GPT-5 Nano vs Kimi K2 Thinking comparison based on?
25 benchmarks have a result for both models as of October 21, 2026. GPT-5 Nano's coding index rests on 1 independent benchmark and Kimi K2 Thinking's on 1. Where only one model has a result, the page says so instead of naming a winner.