# GPT-5-Codex vs Kimi K2 (Jul 2025)

> Kimi K2 (Jul 2025) is the stronger model overall, scoring 40.9 to 37.3 on the Noometry Index.

- Canonical page: https://noometry.com/compare/gpt-5-codex-vs-kimi-k2
- Last updated: 2026-10-10
- Shared benchmarks: 3

## Summary

- They share 3 benchmarks with published results for both. GPT-5-Codex scores higher in 1 category and Kimi K2 (Jul 2025) in 2 categories; 3 gaps are clear of the uncertainty.
- The widest gap is in reasoning, where GPT-5-Codex leads 30.0 to 22.7.
- The biggest single-benchmark swing is WeirdML: 54.5% for GPT-5-Codex and 42.8% for Kimi K2 (Jul 2025).
- Kimi K2 (Jul 2025) is cheaper at $0.57 / $2.30 per million input/output tokens, against $1.25 / $10 for GPT-5-Codex.
- GPT-5-Codex accepts more context: 400K tokens versus 262K.
- Kimi K2 (Jul 2025) has downloadable open weights; the other is API-only.

## Snapshot

| | GPT-5-Codex | Kimi K2 (Jul 2025) |
|---|---|---|
| Provider | OpenAI | Moonshot AI |
| Noometry Index | 37.3 | 40.9 |
| Rank | 190 | 134 |
| Context | 400K | 262K |
| Input $/M | $1.25 | $0.57 |
| Output $/M | $10 | $2.30 |
| Weights | Proprietary | Open |

## Coding

- GPT-5-Codex: 41.9 (#100)
- Kimi K2 (Jul 2025): 43.1 (#83)

| Benchmark | GPT-5-Codex | Kimi K2 (Jul 2025) |
|---|---|---|
| WeirdML | 54.5% | 42.8% |
| SWE-bench Verified (bash only) | — | 63.4% |
| Aider Polyglot | — | 59.1% |
| GSO | — | 4.9% |
| LMArena Coding | — | 1399 |
| ALE-Bench | — | 597.5 |

## Agentic & Tool Use

- GPT-5-Codex: 30.8 (#66)
- Kimi K2 (Jul 2025): 32.2 (#59)

| Benchmark | GPT-5-Codex | Kimi K2 (Jul 2025) |
|---|---|---|
| Terminal-Bench | 44.3% | 35.7% |
| Berkeley Function Calling Leaderboard | — | 59.1% |
| METR Time Horizons | — | 59.2% |

## Reasoning

- GPT-5-Codex: 30.0 (#80)
- Kimi K2 (Jul 2025): 22.7 (#173)

| Benchmark | GPT-5-Codex | Kimi K2 (Jul 2025) |
|---|---|---|
| Kagi LLM Benchmark | 70.3% | 64.4% |
| SimpleBench | — | 26.3% |
| LMArena Hard Prompts | — | 1384 |
| Epoch Capabilities Index | — | 146.02 |
| ForecastBench | — | 60.2 |

## Math

- GPT-5-Codex: —
- Kimi K2 (Jul 2025): 40.1 (#81)

| Benchmark | GPT-5-Codex | Kimi K2 (Jul 2025) |
|---|---|---|
| Omni-MATH | — | 65.4% |
| LMArena Math | — | 1396 |
| FrontierMath (Feb 2025 set) | — | 21.4% |
| FrontierMath Tier 4 (v1) | — | 0% |

## Knowledge

- GPT-5-Codex: —
- Kimi K2 (Jul 2025): 36.9 (#153)

| Benchmark | GPT-5-Codex | Kimi K2 (Jul 2025) |
|---|---|---|
| MMLU-Pro | — | 81.9% |
| Confabulations | — | 20.4% |
| Vectara Hallucination Rate | — | 17.9% |
| GPQA (HELM) | — | 65.3% |
| LMArena Expert | — | 1363 |

## Multilingual

- GPT-5-Codex: —
- Kimi K2 (Jul 2025): 49.8 (#125)

| Benchmark | GPT-5-Codex | Kimi K2 (Jul 2025) |
|---|---|---|
| LMArena Non-English | — | 1372 |
| LMArena Chinese | — | 1416 |
| LMArena French | — | 1379 |
| LMArena German | — | 1386 |
| LMArena Japanese | — | 1349 |
| LMArena Korean | — | 1324 |
| LMArena Russian | — | 1384 |
| LMArena Spanish | — | 1383 |

## Instruction Following

- GPT-5-Codex: —
- Kimi K2 (Jul 2025): 71.3 (#151)

| Benchmark | GPT-5-Codex | Kimi K2 (Jul 2025) |
|---|---|---|
| IFEval | — | 85% |
| LMArena Instruction Following | — | 1347 |

## Long Context

- GPT-5-Codex: —
- Kimi K2 (Jul 2025): 41.2 (#140)

| Benchmark | GPT-5-Codex | Kimi K2 (Jul 2025) |
|---|---|---|
| Fiction.LiveBench | — | 66.7% |
| CL-bench | — | 17.6% |
| LMArena Longer Query | — | 1353 |

## Writing & Preference

- GPT-5-Codex: —
- Kimi K2 (Jul 2025): 62.5 (#76)

| Benchmark | GPT-5-Codex | Kimi K2 (Jul 2025) |
|---|---|---|
| LMArena Text | — | 1380 |
| LMArena Creative Writing | — | 1349 |
| Short-Story Creative Writing | — | 85.6% |
| EQ-Bench Creative Writing | — | 1666 |
| WildBench | — | 86.2% |
| LMArena Multi-Turn | — | 1371 |

## FAQ

### Is GPT-5-Codex better than Kimi K2 (Jul 2025)?

Kimi K2 (Jul 2025) is the stronger model overall, scoring 40.9 to 37.3 on the Noometry Index.

### Which is cheaper, GPT-5-Codex or Kimi K2 (Jul 2025)?

Kimi K2 (Jul 2025) is cheaper. It lists at $0.57 per million input tokens and $2.30 per million output tokens; GPT-5-Codex lists at $1.25 and $10.

### Is GPT-5-Codex or Kimi K2 (Jul 2025) better for coding?

Kimi K2 (Jul 2025) scores higher on coding benchmarks: 43.1 versus 41.9 in the Noometry coding category.

### Which has the bigger context window?

GPT-5-Codex does, with 400K tokens against 262K.

### How many benchmarks do GPT-5-Codex and Kimi K2 (Jul 2025) share?

3 benchmarks have published results for both models. GPT-5-Codex has 3 scored results on Noometry and Kimi K2 (Jul 2025) has 42.