Model comparison
GPT-5 Nano vs Kimi K2.5 Instant
Kimi K2.5 Instant is the stronger model overall, scoring 43.6 to 33.5 on the Noometry Index.
Last verified . 16 shared benchmarks.
Summary
- They share 16 benchmarks with published results for both. GPT-5 Nano scores higher in 0 categories and Kimi K2.5 Instant in 9 categories; 8 gaps are clear of the uncertainty.
- The widest gap is in writing & preference, where Kimi K2.5 Instant leads 60.6 to 39.1.
- Kimi K2.5 Instant has downloadable open weights; the other is API-only.
Side by side
| GPT-5 Nano | Kimi K2.5 Instant | |
|---|---|---|
| Provider | OpenAI | Moonshot AI |
| Noometry Index | 33.5 | 43.6 |
| Released | 2025-08-07 | — |
| Weights | Proprietary | Open |
| Context window | 400K | — |
| Max output | 128K | — |
| Input $ / M tokens | $0.05 | — |
| Output $ / M tokens | $0.40 | — |
| Results tracked | 49 | 18 |
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Category by category
Coding Kimi K2.5 Instant leads
GPT-5 Nano: 33.6 (#254), Kimi K2.5 Instant: 42.6 (#97)
| Benchmark | GPT-5 Nano | Kimi K2.5 Instant |
|---|---|---|
| LMArena Coding | 1351 | 1484 |
| SWE-bench Verified (bash only) | 34.8% | — |
| LMArena WebDev | — | 1404 |
| WeirdML | 38.1% | — |
| ALE-Bench | 718.67 | — |
Agentic & Tool Use Not comparable
GPT-5 Nano: 25.8 (#106), Kimi K2.5 Instant: —
| Benchmark | GPT-5 Nano | Kimi K2.5 Instant |
|---|---|---|
| Terminal-Bench | 21.8% | — |
| Berkeley Function Calling Leaderboard | 51.5% | — |
Reasoning Kimi K2.5 Instant leads
GPT-5 Nano: 16.3 (#306), Kimi K2.5 Instant: 29.7 (#90)
| Benchmark | GPT-5 Nano | Kimi K2.5 Instant |
|---|---|---|
| LMArena Hard Prompts | 1328 | 1443 |
| ARC-AGI-2 | 2.6% | — |
| Kagi LLM Benchmark | 62.2% | — |
| ARC-AGI-1 | 20.7% | — |
| Chess Puzzles | 27% | — |
| Mystery Game Puzzles | 9% | — |
| DTBench | 62.7% | — |
| LMCA | 7.9% | — |
| Epoch Capabilities Index | 139.38 | — |
| ForecastBench | 59.1 | — |
Math Kimi K2.5 Instant leads
GPT-5 Nano: 29.4 (#241), Kimi K2.5 Instant: 39.4 (#105)
| Benchmark | GPT-5 Nano | Kimi K2.5 Instant |
|---|---|---|
| LMArena Math | 1317 | 1442 |
| FrontierMath (Tiers 1-3) | 20% | — |
| FrontierMath Tier 4 | 2.4% | — |
| OTIS Mock AIME 2024-2025 | 81.1% | — |
| ProofBench | 12% | — |
| Omni-MATH | 54.6% | — |
| MATH Level 5 | 95.2% | — |
| FrontierMath (Feb 2025 set) | 8.3% | — |
| FrontierMath Tier 4 (v1) | 2.1% | — |
Knowledge Kimi K2.5 Instant leads
GPT-5 Nano: 35.9 (#178), Kimi K2.5 Instant: 40.2 (#123)
| Benchmark | GPT-5 Nano | Kimi K2.5 Instant |
|---|---|---|
| LMArena Expert | 1321 | 1440 |
| GPQA Diamond | 69.4% | — |
| SimpleQA Verified | 11.7% | — |
| MMLU-Pro | 77.8% | — |
| Vectara Hallucination Rate | 10.5% | — |
| GPQA (HELM) | 67.9% | — |
Multimodal Kimi K2.5 Instant leads
GPT-5 Nano: 31.3 (#108), Kimi K2.5 Instant: 40.2 (#50)
| Benchmark | GPT-5 Nano | Kimi K2.5 Instant |
|---|---|---|
| LMArena Vision | 1159 | 1254 |
| VPCT | 37.2% | — |
Multilingual Kimi K2.5 Instant leads
GPT-5 Nano: 45.3 (#172), Kimi K2.5 Instant: 52.0 (#94)
| Benchmark | GPT-5 Nano | Kimi K2.5 Instant |
|---|---|---|
| LMArena Non-English | 1313 | 1406 |
| LMArena Chinese | 1356 | 1449 |
| LMArena German | 1327 | 1413 |
| LMArena Korean | 1269 | 1378 |
| LMArena Russian | 1296 | 1404 |
| LMArena Spanish | 1360 | 1447 |
| LMArena French | — | 1403 |
| LMArena Japanese | 1226 | — |
Instruction Following Too close to call
GPT-5 Nano: 75.0 (#79), Kimi K2.5 Instant: 75.3 (#65)
| Benchmark | GPT-5 Nano | Kimi K2.5 Instant |
|---|---|---|
| LMArena Instruction Following | 1306 | 1430 |
| IFEval | 93.2% | — |
Long Context Kimi K2.5 Instant leads
GPT-5 Nano: 31.3 (#281), Kimi K2.5 Instant: 43.9 (#83)
| Benchmark | GPT-5 Nano | Kimi K2.5 Instant |
|---|---|---|
| LMArena Longer Query | 1312 | 1435 |
| Fiction.LiveBench | 44.4% | — |
Writing & Preference Kimi K2.5 Instant leads
GPT-5 Nano: 39.1 (#249), Kimi K2.5 Instant: 60.6 (#95)
| Benchmark | GPT-5 Nano | Kimi K2.5 Instant |
|---|---|---|
| LMArena Text | 1320 | 1420 |
| LMArena Creative Writing | 1249 | 1381 |
| LMArena Multi-Turn | 1311 | 1427 |
| EQ-Bench Creative Writing | 705 | — |
| WildBench | 80.6% | — |
Frequently asked questions
Is GPT-5 Nano better than Kimi K2.5 Instant?
Kimi K2.5 Instant is the stronger model overall, scoring 43.6 to 33.5 on the Noometry Index.
Is GPT-5 Nano or Kimi K2.5 Instant better for coding?
Kimi K2.5 Instant scores higher on coding benchmarks: 42.6 versus 33.6 in the Noometry coding category.
How many benchmarks do GPT-5 Nano and Kimi K2.5 Instant share?
16 benchmarks have published results for both models. GPT-5 Nano has 49 scored results on Noometry and Kimi K2.5 Instant has 18.