# GPT-5.1 vs Kimi K2.5

> GPT-5.1 and Kimi K2.5 score almost the same on the Noometry Index (48.8 vs 47.8), so choose on price, context window or the category you care about most.

- Canonical page: https://noometry.com/compare/gpt-5-1-vs-kimi-k2-5
- Last updated: 2026-10-10
- Shared benchmarks: 43

## Summary

- They share 43 benchmarks with published results for both. GPT-5.1 scores higher in 3 categories and Kimi K2.5 in 7 categories; 7 gaps are clear of the uncertainty.
- The widest gap is in reasoning, where GPT-5.1 leads 39.9 to 31.2.
- The biggest single-benchmark swing is Chess Puzzles: 32% for GPT-5.1 and 12% for Kimi K2.5.
- Kimi K2.5 is cheaper at $0.45 / $2.25 per million input/output tokens, against $1.25 / $10 for GPT-5.1.
- GPT-5.1 accepts more context: 400K tokens versus 262K.
- Kimi K2.5 has downloadable open weights; the other is API-only.

## Snapshot

| | GPT-5.1 | Kimi K2.5 |
|---|---|---|
| Provider | OpenAI | Moonshot AI |
| Noometry Index | 48.8 | 47.8 |
| Rank | 47 | 50 |
| Context | 400K | 262K |
| Input $/M | $1.25 | $0.45 |
| Output $/M | $10 | $2.25 |
| Weights | Proprietary | Open |

## Coding

- GPT-5.1: 46.9 (#59)
- Kimi K2.5: 48.7 (#48)

| Benchmark | GPT-5.1 | Kimi K2.5 |
|---|---|---|
| SWE-bench Verified | 68% | 73.8% |
| SWE-bench Verified (bash only) | 66% | 70.8% |
| LMArena WebDev | 1395 | 1436 |
| SciCode | 43.3% | 49% |
| WeirdML | 60.8% | 45.6% |
| LMArena Coding | 1454 | 1474 |
| ALE-Bench | 1,192 | 821.65 |
| SWE-bench Multilingual | — | 67.3% |
| GSO | 13.7% | — |
| LiveBench Coding | 72.5% | — |

## Agentic & Tool Use

- GPT-5.1: 32.5 (#55)
- Kimi K2.5: 34.0 (#44)

| Benchmark | GPT-5.1 | Kimi K2.5 |
|---|---|---|
| Terminal-Bench | 47.6% | 43.2% |
| Vending-Bench 2 | 1,473 | 1,198 |
| DeepResearch Bench | 42.8% | — |
| OSWorld | — | 63.3% |
| LMArena Search | 1199 | — |

## Reasoning

- GPT-5.1: 39.9 (#50)
- Kimi K2.5: 31.2 (#74)

| Benchmark | GPT-5.1 | Kimi K2.5 |
|---|---|---|
| ARC-AGI-2 | 17.6% | 11.8% |
| SimpleBench | 53.2% | 46.8% |
| ARC-AGI-1 | 72.8% | 65.3% |
| CritPt | 4.9% | 3.1% |
| Chess Puzzles | 32% | 12% |
| EnigmaEval | 11.2% | 3.4% |
| LMArena Hard Prompts | 1457 | 1454 |
| Epoch Capabilities Index | 149.66 | 148.05 |
| Kagi LLM Benchmark | — | 78.5% |
| NYT Connections (extended) | — | 69.9% |
| Thematic Generalization | — | 69.4% |
| LiveBench Reasoning | 95.8% | — |
| Mystery Game Puzzles | 19% | — |
| DTBench | 90.1% | — |
| LiveBench Data Analysis | 72.1% | — |
| LMCA | 43.9% | — |
| ForecastBench | 58.1 | — |
| LiveBench | 78.8% | — |

## Math

- GPT-5.1: 50.3 (#45)
- Kimi K2.5: 50.3 (#46)

| Benchmark | GPT-5.1 | Kimi K2.5 |
|---|---|---|
| OTIS Mock AIME 2024-2025 | 88.6% | 92.2% |
| LMArena Math | 1446 | 1470 |
| FrontierMath (Feb 2025 set) | 31% | 27.9% |
| FrontierMath Tier 4 (v1) | 12.5% | 4.2% |
| MathArena Final-Answer Competitions | — | 62.3% |
| Omni-MATH | 46.4% | — |
| LiveBench Math | 94.5% | — |

## Knowledge

- GPT-5.1: 50.5 (#65)
- Kimi K2.5: 53.6 (#52)

| Benchmark | GPT-5.1 | Kimi K2.5 |
|---|---|---|
| GPQA Diamond | 87.6% | 87.6% |
| Humanity's Last Exam | 23.7% | 24.4% |
| SimpleQA Verified | 48% | 34.3% |
| Vectara Hallucination Rate | 10.9% | 14.2% |
| LMArena Expert | 1470 | 1466 |
| MMLU-Pro | 57.9% | — |
| GPQA (HELM) | 44.2% | — |

## Multimodal

- GPT-5.1: 44.0 (#17)
- Kimi K2.5: 40.4 (#37)

| Benchmark | GPT-5.1 | Kimi K2.5 |
|---|---|---|
| LMArena Vision | 1250 | 1269 |
| LMArena Document | 1403 | 1430 |
| VPCT | 58.7% | — |

## Multilingual

- GPT-5.1: 54.0 (#51)
- Kimi K2.5: 54.1 (#50)

| Benchmark | GPT-5.1 | Kimi K2.5 |
|---|---|---|
| LMArena Non-English | 1431 | 1433 |
| LMArena Chinese | 1495 | 1495 |
| LMArena French | 1451 | 1454 |
| LMArena German | 1439 | 1441 |
| LMArena Japanese | 1453 | 1422 |
| LMArena Korean | 1401 | 1412 |
| LMArena Russian | 1435 | 1436 |
| LMArena Spanish | 1430 | 1450 |

## Instruction Following

- GPT-5.1: 84.0 (#1)
- Kimi K2.5: 75.5 (#60)

| Benchmark | GPT-5.1 | Kimi K2.5 |
|---|---|---|
| LMArena Instruction Following | 1442 | 1431 |
| LiveBench Instruction Following | 93.3% | — |
| IFEval | 93.5% | — |

## Long Context

- GPT-5.1: 47.6 (#14)
- Kimi K2.5: 52.1 (#7)

| Benchmark | GPT-5.1 | Kimi K2.5 |
|---|---|---|
| CL-bench | 23.7% | 19.3% |
| CL-bench Life | 17.3% | 13.2% |
| LMArena Longer Query | 1448 | 1445 |
| Fiction.LiveBench | — | 86.1% |

## Writing & Preference

- GPT-5.1: 64.7 (#53)
- Kimi K2.5: 65.3 (#51)

| Benchmark | GPT-5.1 | Kimi K2.5 |
|---|---|---|
| LMArena Text | 1443 | 1445 |
| LMArena Creative Writing | 1427 | 1423 |
| LMArena Multi-Turn | 1449 | 1444 |
| EQ-Bench Creative Writing | — | 1579 |
| WildBench | 86.3% | — |
| LiveBench Language | 80.2% | — |

## FAQ

### Is GPT-5.1 better than Kimi K2.5?

GPT-5.1 and Kimi K2.5 score almost the same on the Noometry Index (48.8 vs 47.8), so choose on price, context window or the category you care about most.

### Which is cheaper, GPT-5.1 or Kimi K2.5?

Kimi K2.5 is cheaper. It lists at $0.45 per million input tokens and $2.25 per million output tokens; GPT-5.1 lists at $1.25 and $10.

### Is GPT-5.1 or Kimi K2.5 better for coding?

Kimi K2.5 scores higher on coding benchmarks: 48.7 versus 46.9 in the Noometry coding category.

### Which has the bigger context window?

GPT-5.1 does, with 400K tokens against 262K.

### How many benchmarks do GPT-5.1 and Kimi K2.5 share?

43 benchmarks have published results for both models. GPT-5.1 has 63 scored results on Noometry and Kimi K2.5 has 51.