# Kimi K2 (Jul 2025) vs Mercury 2.5

> Kimi K2 (Jul 2025) is the stronger model overall, scoring 41.2 to 33.5 on the Noometry Index. Mercury 2.5 costs 15× 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-2-5
- Last updated: 2026-10-10
- Shared benchmarks: 1

## Summary

- They share 1 benchmark with published results for both. Kimi K2 (Jul 2025) scores higher in 3 categories and Mercury 2.5 in 0 categories; 2 gaps are clear of the uncertainty.
- The widest gap is in math, where Kimi K2 (Jul 2025) leads 42.7 to 23.3.
- Mercury 2.5 is cheaper at $0.04 / $0.15 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 260K.
- Kimi K2 (Jul 2025) has downloadable open weights; the other is API-only.

## Snapshot

| | Kimi K2 (Jul 2025) | Mercury 2.5 |
|---|---|---|
| Provider | Moonshot AI | Inception |
| Noometry Index | 41.2 | 33.5 |
| Rank | 140 | 242 |
| Context | 262K | 260K |
| Input $/M | $0.57 | $0.04 |
| Output $/M | $2.30 | $0.15 |
| Weights | Open | Proprietary |

## Coding

- Kimi K2 (Jul 2025): 42.4 (#102)
- Mercury 2.5: 39.5 (#156)

| Benchmark | Kimi K2 (Jul 2025) | Mercury 2.5 |
|---|---|---|
| ALE-Bench | 597.5 | 301.65 |
| SWE-bench Verified (bash only) | 63.4% | — |
| Aider Polyglot | 59.1% | — |
| SciCode | — | 38.5% |
| GSO | 4.9% | — |
| WeirdML | 42.8% | — |
| LMArena Coding | 1399 | — |

## Agentic & Tool Use

- Kimi K2 (Jul 2025): 32.4 (#64)
- Mercury 2.5: —

| Benchmark | Kimi K2 (Jul 2025) | Mercury 2.5 |
|---|---|---|
| Terminal-Bench | 35.7% | — |
| Berkeley Function Calling Leaderboard | 59.1% | — |
| METR Time Horizons | 59.2% | — |

## Reasoning

- Kimi K2 (Jul 2025): 23.3 (#179)
- Mercury 2.5: 22.4 (#193)

| Benchmark | Kimi K2 (Jul 2025) | Mercury 2.5 |
|---|---|---|
| SimpleBench | 26.3% | — |
| Kagi LLM Benchmark | 64.4% | — |
| CritPt | — | 0% |
| LMArena Hard Prompts | 1384 | — |
| Epoch Capabilities Index | 146.01 | — |
| ForecastBench | 60.2 | — |

## Math

- Kimi K2 (Jul 2025): 42.7 (#83)
- Mercury 2.5: 23.3 (#272)

| Benchmark | Kimi K2 (Jul 2025) | Mercury 2.5 |
|---|---|---|
| ProofBench | — | 3% |
| Omni-MATH | 65.4% | — |
| LMArena Math | 1397 | — |
| FrontierMath (Feb 2025 set) | 21.4% | — |
| FrontierMath Tier 4 (v1) | 0% | — |

## Knowledge

- Kimi K2 (Jul 2025): 37.3 (#157)
- Mercury 2.5: —

| Benchmark | Kimi K2 (Jul 2025) | Mercury 2.5 |
|---|---|---|
| MMLU-Pro | 81.9% | — |
| Confabulations | 20.4% | — |
| Vectara Hallucination Rate | 17.9% | — |
| GPQA (HELM) | 65.3% | — |
| LMArena Expert | 1365 | — |

## Multilingual

- Kimi K2 (Jul 2025): 49.6 (#130)
- Mercury 2.5: —

| Benchmark | Kimi K2 (Jul 2025) | Mercury 2.5 |
|---|---|---|
| LMArena Non-English | 1372 | — |
| LMArena Chinese | 1415 | — |
| LMArena French | 1379 | — |
| LMArena German | 1387 | — |
| LMArena Japanese | 1349 | — |
| LMArena Korean | 1325 | — |
| LMArena Russian | 1385 | — |
| LMArena Spanish | 1386 | — |

## Instruction Following

- Kimi K2 (Jul 2025): 71.1 (#156)
- Mercury 2.5: —

| Benchmark | Kimi K2 (Jul 2025) | Mercury 2.5 |
|---|---|---|
| IFEval | 85% | — |
| LMArena Instruction Following | 1348 | — |

## Long Context

- Kimi K2 (Jul 2025): 41.2 (#145)
- Mercury 2.5: —

| Benchmark | Kimi K2 (Jul 2025) | Mercury 2.5 |
|---|---|---|
| Fiction.LiveBench | 66.7% | — |
| CL-bench | 17.6% | — |
| LMArena Longer Query | 1353 | — |

## Writing & Preference

- Kimi K2 (Jul 2025): 62.3 (#78)
- Mercury 2.5: —

| Benchmark | Kimi K2 (Jul 2025) | Mercury 2.5 |
|---|---|---|
| LMArena Text | 1380 | — |
| LMArena Creative Writing | 1350 | — |
| Short-Story Creative Writing | 85.6% | — |
| EQ-Bench Creative Writing | 1666 | — |
| WildBench | 86.2% | — |
| LMArena Multi-Turn | 1371 | — |

## FAQ

### Is Kimi K2 (Jul 2025) better than Mercury 2.5?

Kimi K2 (Jul 2025) is the stronger model overall, scoring 41.2 to 33.5 on the Noometry Index. Mercury 2.5 costs 15× 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 2.5?

Mercury 2.5 is cheaper. It lists at $0.04 per million input tokens and $0.15 per million output tokens; Kimi K2 (Jul 2025) lists at $0.57 and $2.30.

### Is Kimi K2 (Jul 2025) or Mercury 2.5 better for coding?

Kimi K2 (Jul 2025) scores higher on coding benchmarks: 42.4 versus 39.5 in the Noometry coding category.

### Which has the bigger context window?

Kimi K2 (Jul 2025) does, with 262K tokens against 260K.

### How many benchmarks do Kimi K2 (Jul 2025) and Mercury 2.5 share?

1 benchmark has published results for both models. Kimi K2 (Jul 2025) has 42 scored results on Noometry and Mercury 2.5 has 4.