Model comparison
Kimi K2.5 vs Mercury 2
Kimi K2.5 is the stronger model overall, scoring 48.1 to 39.1 on the Noometry Index. Mercury 2 costs 2.4× less per token, which makes it the better buy when Kimi K2.5's lead doesn't matter for your workload.
Last verified . 17 shared benchmarks.
Summary
- They share 17 benchmarks with published results for both. Kimi K2.5 scores higher in 7 categories and Mercury 2 in 0 categories; 7 gaps are clear of the uncertainty.
- The widest gap is in knowledge, where Kimi K2.5 leads 53.6 to 36.2.
- The biggest single-benchmark swing is SciCode: 49% for Kimi K2.5 and 38.7% for Mercury 2.
- Mercury 2 is cheaper at $0.25 / $0.75 per million input/output tokens, against $0.45 / $2.25 for Kimi K2.5.
- Kimi K2.5 accepts more context: 262K tokens versus 128K.
- Kimi K2.5 has downloadable open weights; the other is API-only.
Side by side
| Kimi K2.5 | Mercury 2 | |
|---|---|---|
| Provider | Moonshot AI | Inception |
| Noometry Index | 48.1 | 39.1 |
| Released | 2026-01-27 | 2026-02-20 |
| Weights | Open | Proprietary |
| Context window | 262K | 128K |
| Max output | 262K | 50K |
| Input $ / M tokens | $0.45 | $0.25 |
| Output $ / M tokens | $2.25 | $0.75 |
| Results tracked | 51 | 17 |
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Category by category
Coding Kimi K2.5 leads
Kimi K2.5: 48.8 (#53), Mercury 2: 33.5 (#255)
| Benchmark | Kimi K2.5 | Mercury 2 |
|---|---|---|
| LMArena WebDev | 1437 | 1171 |
| SciCode | 49% | 38.7% |
| WeirdML | 45.6% | 43.2% |
| LMArena Coding | 1474 | 1391 |
| ALE-Bench | 821.65 | 785.58 |
| SWE-bench Verified | 73.8% | — |
| SWE-bench Verified (bash only) | 70.8% | — |
| SWE-bench Multilingual | 67.3% | — |
Agentic & Tool Use Not comparable
Kimi K2.5: 34.2 (#48), Mercury 2: —
| Benchmark | Kimi K2.5 | Mercury 2 |
|---|---|---|
| Terminal-Bench | 43.2% | — |
| OSWorld | 63.3% | — |
| Vending-Bench 2 | 1,198 | — |
Reasoning Kimi K2.5 leads
Kimi K2.5: 31.2 (#80), Mercury 2: 23.8 (#170)
| Benchmark | Kimi K2.5 | Mercury 2 |
|---|---|---|
| CritPt | 3.1% | 0.8% |
| LMArena Hard Prompts | 1453 | 1362 |
| ARC-AGI-2 | 11.8% | — |
| SimpleBench | 46.8% | — |
| Kagi LLM Benchmark | 78.5% | — |
| NYT Connections (extended) | 69.9% | — |
| ARC-AGI-1 | 65.3% | — |
| Chess Puzzles | 12% | — |
| EnigmaEval | 3.4% | — |
| Thematic Generalization | 69.4% | — |
| Epoch Capabilities Index | 148.03 | — |
Math Not comparable
Kimi K2.5: 51.8 (#53), Mercury 2: —
| Benchmark | Kimi K2.5 | Mercury 2 |
|---|---|---|
| MathArena Final-Answer Competitions | 62.3% | — |
| OTIS Mock AIME 2024-2025 | 92.2% | — |
| LMArena Math | 1470 | — |
| FrontierMath (Feb 2025 set) | 27.9% | — |
| FrontierMath Tier 4 (v1) | 4.2% | — |
Knowledge Kimi K2.5 leads
Kimi K2.5: 53.6 (#56), Mercury 2: 36.2 (#172)
| Benchmark | Kimi K2.5 | Mercury 2 |
|---|---|---|
| Vectara Hallucination Rate | 14.2% | 12.3% |
| LMArena Expert | 1466 | 1358 |
| GPQA Diamond | 87.6% | — |
| Humanity's Last Exam | 24.4% | — |
| SimpleQA Verified | 34.3% | — |
Multimodal Not comparable
Kimi K2.5: 41.1 (#39), Mercury 2: —
| Benchmark | Kimi K2.5 | Mercury 2 |
|---|---|---|
| LMArena Vision | 1269 | — |
| LMArena Document | 1430 | — |
Multilingual Kimi K2.5 leads
Kimi K2.5: 53.9 (#53), Mercury 2: 46.6 (#157)
| Benchmark | Kimi K2.5 | Mercury 2 |
|---|---|---|
| LMArena Non-English | 1433 | 1331 |
| LMArena Chinese | 1495 | 1417 |
| LMArena Russian | 1435 | 1304 |
| LMArena French | 1454 | — |
| LMArena German | 1441 | — |
| LMArena Japanese | 1421 | — |
| LMArena Korean | 1410 | — |
| LMArena Spanish | 1450 | — |
Instruction Following Kimi K2.5 leads
Kimi K2.5: 75.3 (#64), Mercury 2: 70.2 (#165)
| Benchmark | Kimi K2.5 | Mercury 2 |
|---|---|---|
| LMArena Instruction Following | 1431 | 1329 |
Long Context Kimi K2.5 leads
Kimi K2.5: 52.1 (#7), Mercury 2: 40.5 (#154)
| Benchmark | Kimi K2.5 | Mercury 2 |
|---|---|---|
| LMArena Longer Query | 1445 | 1330 |
| Fiction.LiveBench | 86.1% | — |
| CL-bench | 19.3% | — |
| CL-bench Life | 13.2% | — |
Writing & Preference Kimi K2.5 leads
Kimi K2.5: 65.1 (#53), Mercury 2: 53.8 (#155)
| Benchmark | Kimi K2.5 | Mercury 2 |
|---|---|---|
| LMArena Text | 1445 | 1355 |
| LMArena Creative Writing | 1423 | 1289 |
| LMArena Multi-Turn | 1444 | 1358 |
| EQ-Bench Creative Writing | 1579 | — |
Frequently asked questions
Is Kimi K2.5 better than Mercury 2?
Kimi K2.5 is the stronger model overall, scoring 48.1 to 39.1 on the Noometry Index. Mercury 2 costs 2.4× less per token, which makes it the better buy when Kimi K2.5's lead doesn't matter for your workload.
Which is cheaper, Kimi K2.5 or Mercury 2?
Mercury 2 is cheaper. It lists at $0.25 per million input tokens and $0.75 per million output tokens; Kimi K2.5 lists at $0.45 and $2.25.
Is Kimi K2.5 or Mercury 2 better for coding?
Kimi K2.5 scores higher on coding benchmarks: 48.8 versus 33.5 in the Noometry coding category.
Which has the bigger context window?
Kimi K2.5 does, with 262K tokens against 128K.
How many benchmarks do Kimi K2.5 and Mercury 2 share?
17 benchmarks have published results for both models. Kimi K2.5 has 51 scored results on Noometry and Mercury 2 has 17.