# Kimi K2 (Jul 2025) vs Mercury 2

> Kimi K2 (Jul 2025) is the stronger model overall, scoring 40.9 to 38.8 on the Noometry Index. Mercury 2 costs 2.7× less per token, which makes it the better buy when Kimi K2 (Jul 2025)'s lead doesn't matter for your workload.

- Canonical page: https://noometry.com/compare/kimi-k2-vs-mercury-2
- Last updated: 2026-10-10
- Shared benchmarks: 14

## Summary

- They share 14 benchmarks with published results for both. Kimi K2 (Jul 2025) scores higher in 6 categories and Mercury 2 in 1 category; 4 gaps are clear of the uncertainty.
- The widest gap is in coding, where Kimi K2 (Jul 2025) leads 43.1 to 33.2.
- The biggest single-benchmark swing is Vectara Hallucination Rate: 17.9% for Kimi K2 (Jul 2025) and 12.3% for Mercury 2.
- Mercury 2 is cheaper at $0.25 / $0.75 per million input/output tokens, against $0.57 / $2.30 for Kimi K2 (Jul 2025).
- Kimi K2 (Jul 2025) accepts more context: 262K tokens versus 128K.
- Kimi K2 (Jul 2025) has downloadable open weights; the other is API-only.

## Snapshot

| | Kimi K2 (Jul 2025) | Mercury 2 |
|---|---|---|
| Provider | Moonshot AI | Inception |
| Noometry Index | 40.9 | 38.8 |
| Rank | 134 | 167 |
| Context | 262K | 128K |
| Input $/M | $0.57 | $0.25 |
| Output $/M | $2.30 | $0.75 |
| Weights | Open | Proprietary |

## Coding

- Kimi K2 (Jul 2025): 43.1 (#83)
- Mercury 2: 33.2 (#250)

| Benchmark | Kimi K2 (Jul 2025) | Mercury 2 |
|---|---|---|
| WeirdML | 42.8% | 43.2% |
| LMArena Coding | 1399 | 1391 |
| ALE-Bench | 597.5 | 785.58 |
| SWE-bench Verified (bash only) | 63.4% | — |
| Aider Polyglot | 59.1% | — |
| LMArena WebDev | — | 1170 |
| SciCode | — | 38.7% |
| GSO | 4.9% | — |

## Agentic & Tool Use

- Kimi K2 (Jul 2025): 32.2 (#59)
- Mercury 2: —

| Benchmark | Kimi K2 (Jul 2025) | Mercury 2 |
|---|---|---|
| Terminal-Bench | 35.7% | — |
| Berkeley Function Calling Leaderboard | 59.1% | — |
| METR Time Horizons | 59.2% | — |

## Reasoning

- Kimi K2 (Jul 2025): 22.7 (#173)
- Mercury 2: 23.0 (#170)

| Benchmark | Kimi K2 (Jul 2025) | Mercury 2 |
|---|---|---|
| LMArena Hard Prompts | 1384 | 1362 |
| SimpleBench | 26.3% | — |
| Kagi LLM Benchmark | 64.4% | — |
| CritPt | — | 0.8% |
| Epoch Capabilities Index | 146.02 | — |
| ForecastBench | 60.2 | — |

## Math

- Kimi K2 (Jul 2025): 40.1 (#81)
- Mercury 2: —

| Benchmark | Kimi K2 (Jul 2025) | Mercury 2 |
|---|---|---|
| Omni-MATH | 65.4% | — |
| LMArena Math | 1396 | — |
| FrontierMath (Feb 2025 set) | 21.4% | — |
| FrontierMath Tier 4 (v1) | 0% | — |

## Knowledge

- Kimi K2 (Jul 2025): 36.9 (#153)
- Mercury 2: 35.6 (#170)

| Benchmark | Kimi K2 (Jul 2025) | Mercury 2 |
|---|---|---|
| Vectara Hallucination Rate | 17.9% | 12.3% |
| LMArena Expert | 1363 | 1358 |
| MMLU-Pro | 81.9% | — |
| Confabulations | 20.4% | — |
| GPQA (HELM) | 65.3% | — |

## Multilingual

- Kimi K2 (Jul 2025): 49.8 (#125)
- Mercury 2: 46.8 (#153)

| Benchmark | Kimi K2 (Jul 2025) | Mercury 2 |
|---|---|---|
| LMArena Non-English | 1372 | 1331 |
| LMArena Chinese | 1416 | 1416 |
| LMArena Russian | 1384 | 1303 |
| LMArena French | 1379 | — |
| LMArena German | 1386 | — |
| LMArena Japanese | 1349 | — |
| LMArena Korean | 1324 | — |
| LMArena Spanish | 1383 | — |

## Instruction Following

- Kimi K2 (Jul 2025): 71.3 (#151)
- Mercury 2: 70.4 (#161)

| Benchmark | Kimi K2 (Jul 2025) | Mercury 2 |
|---|---|---|
| LMArena Instruction Following | 1347 | 1328 |
| IFEval | 85% | — |

## Long Context

- Kimi K2 (Jul 2025): 41.2 (#140)
- Mercury 2: 40.4 (#149)

| Benchmark | Kimi K2 (Jul 2025) | Mercury 2 |
|---|---|---|
| LMArena Longer Query | 1353 | 1329 |
| Fiction.LiveBench | 66.7% | — |
| CL-bench | 17.6% | — |

## Writing & Preference

- Kimi K2 (Jul 2025): 62.5 (#76)
- Mercury 2: 54.0 (#151)

| Benchmark | Kimi K2 (Jul 2025) | Mercury 2 |
|---|---|---|
| LMArena Text | 1380 | 1355 |
| LMArena Creative Writing | 1349 | 1289 |
| LMArena Multi-Turn | 1371 | 1358 |
| Short-Story Creative Writing | 85.6% | — |
| EQ-Bench Creative Writing | 1666 | — |
| WildBench | 86.2% | — |

## FAQ

### Is Kimi K2 (Jul 2025) better than Mercury 2?

Kimi K2 (Jul 2025) is the stronger model overall, scoring 40.9 to 38.8 on the Noometry Index. Mercury 2 costs 2.7× less per token, which makes it the better buy when Kimi K2 (Jul 2025)'s lead doesn't matter for your workload.

### Which is cheaper, Kimi K2 (Jul 2025) or Mercury 2?

Mercury 2 is cheaper. It lists at $0.25 per million input tokens and $0.75 per million output tokens; Kimi K2 (Jul 2025) lists at $0.57 and $2.30.

### Is Kimi K2 (Jul 2025) or Mercury 2 better for coding?

Kimi K2 (Jul 2025) scores higher on coding benchmarks: 43.1 versus 33.2 in the Noometry coding category.

### Which has the bigger context window?

Kimi K2 (Jul 2025) does, with 262K tokens against 128K.

### How many benchmarks do Kimi K2 (Jul 2025) and Mercury 2 share?

14 benchmarks have published results for both models. Kimi K2 (Jul 2025) has 42 scored results on Noometry and Mercury 2 has 17.