Mercury 2.5 vs Kimi K3
Kimi K3 leads Mercury 2.5 on coding, 62.3 to 1.6 on the Vibe Coding Index, and Mercury 2.5 costs 100.0x less per output token ($0.15 vs $15.00 per million). Updated October 21, 2026; 21 benchmarks have a result for both.
Mercury 2.5 or Kimi K3: which to pick
Pick Kimi K3 for coding: it scores 62.3 on the Vibe Coding Index against 1.6 for Mercury 2.5.
Pick Mercury 2.5 for output tokens 100.0x cheaper ($0.15 vs $15.00 per million).
- Shared results
- 21
- Mercury 2.5 only
- 1
- Kimi K3 only
- 96
- Like-for-like categories
- 7 of 9
Only benchmarks that tested both models count toward a pick; a result only one model has is shown but not compared.
Which one for your work
Each card is decided by one number both models carry. Where only one has it, the card says so and makes no call.
Coding
Vibe Coding Index, six public coding benchmarks
Kimi K3
Kimi K3 scores 62.3 against 1.6.
2 and 6 benchmarks behind the scores
Intelligence
AA Intelligence Index
Kimi K3
Kimi K3 leads, 43.6 against 12.3.
Same board, both measured
Agentic work
AA Agentic Index
No call
Only Kimi K3 has a AA Agentic Index result, 50.0.
Directional only
Reasoning
GPQA Diamond
No call
Only Kimi K3 has a GPQA Diamond result, 92.9%.
Directional only
Knowledge
MMLU Pro
No call
Only Kimi K3 has a MMLU Pro result, 88.0%.
Directional only
Web design
Design Arena: websites
No call
Only Kimi K3 has a Design Arena: websites result, 1335.
Directional only
General
Vals Index
No call
Only Kimi K3 has a Vals Index result, 53.0%.
Directional only
Long documents
Listed context window
Kimi K3
Kimi K3 takes 1.05M tokens against 260K.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
Mercury 2.5
Mercury 2.5 $0.0001, Kimi K3 $0.011 per turn.
List prices
Cost per solved task
One SWE-bench Verified task, solved
No call
Only Kimi K3 has the number, $0.81.
Directional only
At a glance
- Coding index
- Mercury 2.5 1.6 from 2 benchmarks, Kimi K3 62.3 from 6 benchmarks.
- Widest category
- Math, 84.0 points apart on average over 1 shared benchmark.
- Widest single gap
- ProofBench: Mercury 2.5 3.0% against Kimi K3 87.0%, 84.0 points apart on a 0 to 100 scale.
- Output price
- Mercury 2.5 $0.15 against Kimi K3 $15.00 per million output tokens, 100.0x apart.
- Context window
- Mercury 2.5 takes 260K tokens, Kimi K3 1.05M.
Benchmark by benchmark
First the score: boards each model leads, per category, where both have a result. Then every board, a category to a fold; bars are each result on a 0 to 100 scale, so compare the two in a row, not one row with another.
| Category | Mercury 2.5 | Bars | Kimi K3 | Ties |
|---|---|---|---|---|
| Coding | 0 | 8 | ||
| Intelligence | 0 | 1 | ||
| Agentic work | 0 | 5 | ||
| Reasoning | 0 | 1 | ||
| Math | 0 | 1 | ||
| Knowledge | 0 | 2 | ||
| General | 0 | 3 | ||
| All shared boards | 0 | 21 |
CodingLike-for-likeSix of these boards feed the Vibe Coding Index08
| Benchmark | Mercury 2.5 | Kimi K3 | Leader |
|---|---|---|---|
| LiveBench coding | Not measured | 59.3% | Only Kimi K3 measured |
| LMArena WebDev | Not measured | 1655 | Only Kimi K3 measured |
| AA Coding Index | Not measured | 76.2 | Only Kimi K3 measured |
| LiveCodeBench (Vals AI) | Not measured | 87.2% | Only Kimi K3 measured |
| SWE-bench Verified (Vals AI) | Not measured | 93.4% | Only Kimi K3 measured |
| Terminal-Bench 4 (Vals AI) | 0.0% | 17.2% | Kimi K3 |
| Vibe Code Bench (Vals AI) | 3.7% | 85.0% | Kimi K3 |
| Code migration (Vals AI) | 4.5% | 16.1% | Kimi K3 |
| ProgramBench (Vals AI) | Not measured | 2.0% | Only Kimi K3 measured |
| IOI (Vals AI) | 2.4% | 48.9% | Kimi K3 |
| Terminal-Bench 2.1 (Vals AI) | 34.5% | 80.9% | Kimi K3 |
| SWE-bench Multimodal (Vals AI) | Not measured | 44.2% | Only Kimi K3 measured |
| Vibe Code Bench 1-100 (Vals AI) | Not measured | 18.2% | Only Kimi K3 measured |
| SkillsBench (Vals AI) | 18.1% | Not measured | Only Mercury 2.5 measured |
| CyberBench (Vals AI) | 45.5% | 75.2% | Kimi K3 |
| SciCode | 38.5% | 59.5% | Kimi K3 |
| FrontierCode | Not measured | 44.2% | Only Kimi K3 measured |
| FrontierSWE | Not measured | 25.9% | Only Kimi K3 measured |
| WeirdML | Not measured | 82.6% | Only Kimi K3 measured |
| ALE-Bench | 301.6 | 1524.5 | Kimi K3 |
| LMArena Text: coding | Not measured | 1508 | Only Kimi K3 measured |
| LMArena Text: software and IT | Not measured | 1499 | Only Kimi K3 measured |
| LMArena WebDev: React | Not measured | 1670 | Only Kimi K3 measured |
| LMArena WebDev: HTML | Not measured | 1644 | Only Kimi K3 measured |
| LMArena WebDev: from an image | Not measured | 1579 | Only Kimi K3 measured |
| Neither model has a result on the other 14 boards here | |||
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index01
| Benchmark | Mercury 2.5 | Kimi K3 | Leader |
|---|---|---|---|
| AA Intelligence Index | 12.3 | 43.6 | Kimi K3 |
| Epoch Capabilities Index | Not measured | 157.9 | Only Kimi K3 measured |
Agentic workLike-for-likePublic boards, shown as published, kept out of the index05
| Benchmark | Mercury 2.5 | Kimi K3 | Leader |
|---|---|---|---|
| AA Agentic Index | Not measured | 50.0 | Only Kimi K3 measured |
| Design Arena: agents building web apps | Not measured | 1295 | Only Kimi K3 measured |
| Design Arena: agents building full-stack apps | Not measured | 1315 | Only Kimi K3 measured |
| Design Arena: agents building mobile apps | Not measured | 1269 | Only Kimi K3 measured |
| Design Arena: agents building Android apps | Not measured | 1250 | Only Kimi K3 measured |
| Design Arena: agents building Godot games | Not measured | 1223 | Only Kimi K3 measured |
| Design Arena: agents building games | Not measured | 1252 | Only Kimi K3 measured |
| Design Arena: HTML slides | Not measured | 1256 | Only Kimi K3 measured |
| Design Arena: PowerPoint slides | Not measured | 1273 | Only Kimi K3 measured |
| Design Arena: spreadsheets | Not measured | 1058 | Only Kimi K3 measured |
| LiveBench research | Not measured | 79.0% | Only Kimi K3 measured |
| LiveBench browser | Not measured | 16.0% | Only Kimi K3 measured |
| LiveBench long agentic | Not measured | 42.8% | Only Kimi K3 measured |
| Finance Agent (Vals AI) | 18.9% | 53.1% | Kimi K3 |
| Tax Agent Bench (Vals AI) | 2.5% | 33.4% | Kimi K3 |
| Legal Research Bench (Vals AI) | 4.3% | 46.1% | Kimi K3 |
| Harvey's Legal Agent Benchmark (Vals AI) | Not measured | 12.9% | Only Kimi K3 measured |
| Excel Modeling Benchmark (Vals AI) | 8.8% | 66.7% | Kimi K3 |
| BioMysteryBench (Vals AI) | Not measured | 72.6% | Only Kimi K3 measured |
| Terminal-Bench-Science (Vals AI) | 0.0% | 1.4% | Kimi K3 |
| Time Horizon Index (Vals AI) | Not measured | 10.5% | Only Kimi K3 measured |
| APEX-Agents | Not measured | 47.8% | Only Kimi K3 measured |
| PostTrainBench | Not measured | 32.0% | Only Kimi K3 measured |
| Vending-Bench 2 | Not measured | $5,165 | Only Kimi K3 measured |
| Neither model has a result on the other 17 boards here | |||
ReasoningLike-for-likePublic boards, shown as published, kept out of the index01
| Benchmark | Mercury 2.5 | Kimi K3 | Leader |
|---|---|---|---|
| GPQA Diamond | Not measured | 92.9% | Only Kimi K3 measured |
| LiveBench reasoning | Not measured | 90.7% | Only Kimi K3 measured |
| MMMU Pro (Vals AI) | Not measured | 88.2% | Only Kimi K3 measured |
| GPQA Diamond (Artificial Analysis run) | Not measured | 93.5% | Only Kimi K3 measured |
| Humanity's Last Exam (Artificial Analysis run) | 11.8% | 46.9% | Kimi K3 |
| GPQA Diamond (Epoch AI run) | Not measured | 93.1% | Only Kimi K3 measured |
| ARC-AGI | Not measured | 94.5% | Only Kimi K3 measured |
| ARC-AGI-2 | Not measured | 60.4% | Only Kimi K3 measured |
| SimpleBench | Not measured | 60.7% | Only Kimi K3 measured |
| Chess puzzles | Not measured | 37.0% | Only Kimi K3 measured |
| Mystery game puzzles | Not measured | 26.0% | Only Kimi K3 measured |
| LMArena Text: hard prompts | Not measured | 1495 | Only Kimi K3 measured |
| LMArena Text: expert | Not measured | 1520 | Only Kimi K3 measured |
| LMArena Text: hard prompts in English | Not measured | 1496 | Only Kimi K3 measured |
| Neither model has a result on the other 8 boards here | |||
MathLike-for-likePublic boards, shown as published, kept out of the index01
| Benchmark | Mercury 2.5 | Kimi K3 | Leader |
|---|---|---|---|
| OTIS Mock AIME | Not measured | 97.2% | Only Kimi K3 measured |
| FrontierMath, tiers 1 to 3 | Not measured | 72.2% | Only Kimi K3 measured |
| FrontierMath, tier 4 | Not measured | 39.0% | Only Kimi K3 measured |
| ProofBench | 3.0% | 87.0% | Kimi K3 |
| LMArena Text: math | Not measured | 1494 | Only Kimi K3 measured |
| LMArena Text: mathematical work | Not measured | 1505 | Only Kimi K3 measured |
| Neither model has a result on the other 7 boards here | |||
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index02
| Benchmark | Mercury 2.5 | Kimi K3 | Leader |
|---|---|---|---|
| MMLU Pro | Not measured | 88.0% | Only Kimi K3 measured |
| LegalBench (Vals AI) | 83.1% | 86.2% | Kimi K3 |
| CorpFin (Vals AI) | Not measured | 71.6% | Only Kimi K3 measured |
| TaxEval (Vals AI) | Not measured | 75.7% | Only Kimi K3 measured |
| MortgageTax (Vals AI) | Not measured | 66.3% | Only Kimi K3 measured |
| MedCode (Vals AI) | 31.3% | 49.4% | Kimi K3 |
| SimpleQA Verified | Not measured | 50.6% | Only Kimi K3 measured |
| LMArena Text: science | Not measured | 1508 | Only Kimi K3 measured |
| LMArena Text: medicine and healthcare | Not measured | 1489 | Only Kimi K3 measured |
| LMArena Text: legal and government | Not measured | 1503 | Only Kimi K3 measured |
| LMArena Text: business and finance | Not measured | 1470 | Only Kimi K3 measured |
| Neither model has a result on the other 7 boards here | |||
Web designDirectional onlyPublic boards, shown as published, kept out of the index8 boards, none shared
| Benchmark | Mercury 2.5 | Kimi K3 | Leader |
|---|---|---|---|
| Design Arena: websites | Not measured | 1335 | Only Kimi K3 measured |
| Design Arena: UI components | Not measured | 1344 | Only Kimi K3 measured |
| Design Arena: game dev | Not measured | 1359 | Only Kimi K3 measured |
| Design Arena: data viz | Not measured | 1351 | Only Kimi K3 measured |
| Design Arena: 3D | Not measured | 1388 | Only Kimi K3 measured |
| Design Arena: all code categories | Not measured | 1360 | Only Kimi K3 measured |
| Design Arena: SVG | Not measured | 1302 | Only Kimi K3 measured |
| LiveBench design | Not measured | 77.2% | Only Kimi K3 measured |
| Neither model has a result on the other 1 board here | |||
GeneralLike-for-likePublic boards, shown as published, kept out of the index03
| Benchmark | Mercury 2.5 | Kimi K3 | Leader |
|---|---|---|---|
| Vals Index | Not measured | 53.0% | Only Kimi K3 measured |
| LiveBench data analysis | Not measured | 78.7% | Only Kimi K3 measured |
| Public Benefits Bench (Vals AI) | 45.3% | 68.2% | Kimi K3 |
| SAGE (Vals AI) | Not measured | 52.8% | Only Kimi K3 measured |
| MedScribe (Vals AI) | 55.1% | 88.0% | Kimi K3 |
| Vals Multimodal Index | Not measured | 73.4% | Only Kimi K3 measured |
| Long context reasoning (AA-LCR) | 71.7% | 88.7% | Kimi K3 |
| DTBench | Not measured | 91.2% | Only Kimi K3 measured |
| LMCA | Not measured | 52.7% | Only Kimi K3 measured |
| Surface Evolver Bench | Not measured | 95.0% | Only Kimi K3 measured |
| Furniture assembly | Not measured | 34.2% | Only Kimi K3 measured |
| LMArena Text | Not measured | 1476 | Only Kimi K3 measured |
| LMArena Text: instruction following | Not measured | 1485 | Only Kimi K3 measured |
| LMArena Text: creative writing | Not measured | 1457 | Only Kimi K3 measured |
| LMArena Text: English | Not measured | 1481 | Only Kimi K3 measured |
| LMArena Text: non-English | Not measured | 1466 | Only Kimi K3 measured |
| LMArena Text: Chinese | Not measured | 1529 | Only Kimi K3 measured |
| LMArena Text: German | Not measured | 1490 | Only Kimi K3 measured |
| LMArena Text: Japanese | Not measured | 1494 | Only Kimi K3 measured |
| LMArena Text: Korean | Not measured | 1460 | Only Kimi K3 measured |
| LMArena Text: French | Not measured | 1492 | Only Kimi K3 measured |
| LMArena Text: Spanish | Not measured | 1472 | Only Kimi K3 measured |
| LMArena Text: Russian | Not measured | 1485 | Only Kimi K3 measured |
| LMArena Text: Polish | Not measured | 1458 | Only Kimi K3 measured |
| LMArena Text: multi-turn | Not measured | 1489 | Only Kimi K3 measured |
| LMArena Text: longer queries | Not measured | 1494 | Only Kimi K3 measured |
| LMArena Text: writing and language | Not measured | 1471 | Only Kimi K3 measured |
| LMArena Text: entertainment and media | Not measured | 1453 | Only Kimi K3 measured |
| Neither model has a result on the other 18 boards here | |||
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
| Benchmark | Mercury 2.5 | Kimi K3 | Leader |
|---|---|---|---|
| Neither model has a result on 5 boards here | |||
What each workload costs
Three fixed token mixes at each model's listed price, so per-token rates become a bill.
Chat turn
1K input + 500 output tokens
Mercury 2.5 costs less
Repository review
50K input + 3K output tokens
Mercury 2.5 costs less
Agent loop
200K input + 10K output tokens
Mercury 2.5 costs less
Listed OpenRouter rates, without cache or batch discounts. A workload that does not fit a model's context window would need splitting.
Specification differences
The leading value in a row is marked; a row with a missing value names no leader. Our two rows are marked in red.
| Specification | Inception Mercury 2.5 | MoonshotAI Kimi K3 |
|---|---|---|
| Maker | Inception | Moonshot AI |
| Weights | No public weights listed | Open weights |
| Released | September 8, 2026 | July 16, 2026 |
| Context window | 260K | 1.05M |
| Input $/Mtok | $0.04 | $3.00 |
| Output $/Mtok | $0.15 | $15.00 |
| Coding index | 1.6 | 62.3 |
| Independent measurements behind it | 2 | 6 |
| Cost per solved task | Not computable | $0.81 |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is Mercury 2.5 better than Kimi K3 for coding?
Pick Kimi K3 for coding: it scores 62.3 on the Vibe Coding Index against 1.6 for Mercury 2.5. Pick Mercury 2.5 for output tokens 100.0x cheaper ($0.15 vs $15.00 per million).
Which is cheaper, Mercury 2.5 or Kimi K3?
Mercury 2.5 costs $0.04 per million input tokens and $0.15 per million output tokens; Kimi K3 costs $3.00 and $15.00. Cost per solved task is known for Kimi K3 only.
Which has the bigger context window, Mercury 2.5 or Kimi K3?
Kimi K3, with 1.05M tokens against 260K.
How many benchmarks is the Mercury 2.5 vs Kimi K3 comparison based on?
21 benchmarks have a result for both models as of October 21, 2026. Mercury 2.5's coding index rests on 2 independent benchmarks and Kimi K3's on 6. Where only one model has a result, the page says so instead of naming a winner.