# GPT-5.6 Luna vs Kimi K2 (Jul 2025)

> GPT-5.6 Luna is the stronger model overall, scoring 54.7 to 40.9 on the Noometry Index.

- Canonical page: https://noometry.com/compare/gpt-5-6-luna-vs-kimi-k2
- Last updated: 2026-10-10
- Shared benchmarks: 23

## Summary

- They share 23 benchmarks with published results for both. GPT-5.6 Luna scores higher in 9 categories and Kimi K2 (Jul 2025) in 0 categories; 9 gaps are clear of the uncertainty.
- The widest gap is in math, where GPT-5.6 Luna leads 77.5 to 40.1.
- The biggest single-benchmark swing is SimpleBench: 46.8% for GPT-5.6 Luna and 26.3% for Kimi K2 (Jul 2025).
- GPT-5.6 Luna is cheaper at $0.20 / $1.20 per million input/output tokens, against $0.57 / $2.30 for Kimi K2 (Jul 2025).
- GPT-5.6 Luna accepts more context: 1.05M tokens versus 262K.
- Kimi K2 (Jul 2025) has downloadable open weights; the other is API-only.

## Snapshot

| | GPT-5.6 Luna | Kimi K2 (Jul 2025) |
|---|---|---|
| Provider | OpenAI | Moonshot AI |
| Noometry Index | 54.7 | 40.9 |
| Rank | 24 | 134 |
| Context | 1.05M | 262K |
| Input $/M | $0.20 | $0.57 |
| Output $/M | $1.20 | $2.30 |
| Weights | Proprietary | Open |

## Coding

- GPT-5.6 Luna: 53.9 (#25)
- Kimi K2 (Jul 2025): 43.1 (#83)

| Benchmark | GPT-5.6 Luna | Kimi K2 (Jul 2025) |
|---|---|---|
| WeirdML | 60.9% | 42.8% |
| LMArena Coding | 1466 | 1399 |
| ALE-Bench | 1,667 | 597.5 |
| DeepSWE | 67.2% | — |
| FrontierCode | 39.8% | — |
| SWE-bench Verified (bash only) | — | 63.4% |
| Aider Polyglot | — | 59.1% |
| CursorBench | 35.9% | — |
| LMArena WebDev | 1517 | — |
| SciCode | 53.6% | — |
| GSO | — | 4.9% |

## Agentic & Tool Use

- GPT-5.6 Luna: 35.3 (#37)
- Kimi K2 (Jul 2025): 32.2 (#59)

| Benchmark | GPT-5.6 Luna | Kimi K2 (Jul 2025) |
|---|---|---|
| Terminal-Bench | — | 35.7% |
| Berkeley Function Calling Leaderboard | — | 59.1% |
| BALROG | 45.6% | — |
| GDP.pdf | 22.7% | — |
| METR Time Horizons | — | 59.2% |
| Vending-Bench 2 | 4,095 | — |

## Reasoning

- GPT-5.6 Luna: 47.5 (#38)
- Kimi K2 (Jul 2025): 22.7 (#173)

| Benchmark | GPT-5.6 Luna | Kimi K2 (Jul 2025) |
|---|---|---|
| SimpleBench | 46.8% | 26.3% |
| Kagi LLM Benchmark | 49.1% | 64.4% |
| LMArena Hard Prompts | 1452 | 1384 |
| Epoch Capabilities Index | 156.32 | 146.02 |
| ARC-AGI-2 | 59.5% | — |
| NYT Connections (extended) | 69.4% | — |
| ARC-AGI-1 | 88% | — |
| CritPt | 20.6% | — |
| Chess Puzzles | 40% | — |
| Mystery Game Puzzles | 21% | — |
| DTBench | 89.1% | — |
| LMCA | 48.5% | — |
| Surface Evolver Bench | 61.9% | — |
| ForecastBench | — | 60.2 |

## Math

- GPT-5.6 Luna: 77.5 (#12)
- Kimi K2 (Jul 2025): 40.1 (#81)

| Benchmark | GPT-5.6 Luna | Kimi K2 (Jul 2025) |
|---|---|---|
| LMArena Math | 1455 | 1396 |
| FrontierMath (Tiers 1-3) | 82.1% | — |
| FrontierMath Tier 4 | 61% | — |
| OTIS Mock AIME 2024-2025 | 98.3% | — |
| ProofBench | 60% | — |
| Omni-MATH | — | 65.4% |
| FrontierMath (Feb 2025 set) | — | 21.4% |
| FrontierMath Tier 4 (v1) | — | 0% |

## Knowledge

- GPT-5.6 Luna: 58.6 (#31)
- Kimi K2 (Jul 2025): 36.9 (#153)

| Benchmark | GPT-5.6 Luna | Kimi K2 (Jul 2025) |
|---|---|---|
| LMArena Expert | 1479 | 1363 |
| GPQA Diamond | 91.6% | — |
| SimpleQA Verified | 41% | — |
| MMLU-Pro | — | 81.9% |
| Confabulations | — | 20.4% |
| Vectara Hallucination Rate | — | 17.9% |
| GPQA (HELM) | — | 65.3% |

## Multimodal

- GPT-5.6 Luna: 43.0 (#22)
- Kimi K2 (Jul 2025): —

| Benchmark | GPT-5.6 Luna | Kimi K2 (Jul 2025) |
|---|---|---|
| LMArena Vision | 1259 | — |
| Blueprint-Bench 2 | 22.6% | — |
| Furniture Assembly | 42.5% | — |
| LMArena Document | 1457 | — |

## Multilingual

- GPT-5.6 Luna: 53.0 (#73)
- Kimi K2 (Jul 2025): 49.8 (#125)

| Benchmark | GPT-5.6 Luna | Kimi K2 (Jul 2025) |
|---|---|---|
| LMArena Non-English | 1418 | 1372 |
| LMArena Chinese | 1469 | 1416 |
| LMArena French | 1457 | 1379 |
| LMArena German | 1459 | 1386 |
| LMArena Japanese | 1416 | 1349 |
| LMArena Korean | 1414 | 1324 |
| LMArena Russian | 1428 | 1384 |
| LMArena Spanish | 1445 | 1383 |

## Instruction Following

- GPT-5.6 Luna: 76.0 (#48)
- Kimi K2 (Jul 2025): 71.3 (#151)

| Benchmark | GPT-5.6 Luna | Kimi K2 (Jul 2025) |
|---|---|---|
| LMArena Instruction Following | 1440 | 1347 |
| IFEval | — | 85% |

## Long Context

- GPT-5.6 Luna: 43.9 (#78)
- Kimi K2 (Jul 2025): 41.2 (#140)

| Benchmark | GPT-5.6 Luna | Kimi K2 (Jul 2025) |
|---|---|---|
| LMArena Longer Query | 1437 | 1353 |
| Fiction.LiveBench | — | 66.7% |
| CL-bench | — | 17.6% |

## Writing & Preference

- GPT-5.6 Luna: 68.3 (#27)
- Kimi K2 (Jul 2025): 62.5 (#76)

| Benchmark | GPT-5.6 Luna | Kimi K2 (Jul 2025) |
|---|---|---|
| LMArena Text | 1432 | 1380 |
| LMArena Creative Writing | 1397 | 1349 |
| EQ-Bench Creative Writing | 1829 | 1666 |
| LMArena Multi-Turn | 1433 | 1371 |
| Short-Story Creative Writing | — | 85.6% |
| WildBench | — | 86.2% |
| EQ-Bench 4 | 1156 | — |

## FAQ

### Is GPT-5.6 Luna better than Kimi K2 (Jul 2025)?

GPT-5.6 Luna is the stronger model overall, scoring 54.7 to 40.9 on the Noometry Index.

### Which is cheaper, GPT-5.6 Luna or Kimi K2 (Jul 2025)?

GPT-5.6 Luna is cheaper. It lists at $0.20 per million input tokens and $1.20 per million output tokens; Kimi K2 (Jul 2025) lists at $0.57 and $2.30.

### Is GPT-5.6 Luna or Kimi K2 (Jul 2025) better for coding?

GPT-5.6 Luna scores higher on coding benchmarks: 53.9 versus 43.1 in the Noometry coding category.

### Which has the bigger context window?

GPT-5.6 Luna does, with 1.05M tokens against 262K.

### How many benchmarks do GPT-5.6 Luna and Kimi K2 (Jul 2025) share?

23 benchmarks have published results for both models. GPT-5.6 Luna has 51 scored results on Noometry and Kimi K2 (Jul 2025) has 42.