Model comparison
Claude Fable 5.1 vs Kimi K2 (Jul 2025)
Claude Fable 5.1 is the stronger model overall, scoring 69.0 to 41.2 on the Noometry Index. Kimi K2 (Jul 2025) costs 20× less per token, which makes it the better buy when Claude Fable 5.1's lead doesn't matter for your workload.
Last verified . 22 shared benchmarks.
Summary
- They share 22 benchmarks with published results for both. Claude Fable 5.1 scores higher in 9 categories and Kimi K2 (Jul 2025) in 0 categories; 9 gaps are clear of the uncertainty.
- The widest gap is in reasoning, where Claude Fable 5.1 leads 76.7 to 23.3.
- The biggest single-benchmark swing is GSO: 88.2% for Claude Fable 5.1 and 4.9% for Kimi K2 (Jul 2025).
- Kimi K2 (Jul 2025) is cheaper at $0.57 / $2.30 per million input/output tokens, against $10 / $50 for Claude Fable 5.1.
- Claude Fable 5.1 accepts more context: 1M tokens versus 262K.
- Kimi K2 (Jul 2025) has downloadable open weights; the other is API-only.
Side by side
| Claude Fable 5.1 | Kimi K2 (Jul 2025) | |
|---|---|---|
| Provider | Anthropic | Moonshot AI |
| Noometry Index | 69.0 | 41.2 |
| Released | 2026-09-01 | 2025-07-12 |
| Weights | Proprietary | Open |
| Context window | 1M | 262K |
| Max output | 128K | 262K |
| Input $ / M tokens | $10 | $0.57 |
| Output $ / M tokens | $50 | $2.30 |
| Results tracked | 52 | 42 |
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Category by category
Coding Claude Fable 5.1 leads
Claude Fable 5.1: 74.7 (#1), Kimi K2 (Jul 2025): 42.4 (#102)
| Benchmark | Claude Fable 5.1 | Kimi K2 (Jul 2025) |
|---|---|---|
| GSO | 88.2% | 4.9% |
| WeirdML | 92.9% | 42.8% |
| LMArena Coding | 1528 | 1399 |
| ALE-Bench | 2,143 | 597.5 |
| FrontierCode | 50.9% | — |
| SWE-bench Verified (bash only) | — | 63.4% |
| Aider Polyglot | — | 59.1% |
| CursorBench | 51.8% | — |
| LMArena WebDev | 1744 | — |
| FrontierSWE | 56.3% | — |
| SciCode | 63.1% | — |
| MirrorCode | 73.3% | — |
Agentic & Tool Use Claude Fable 5.1 leads
Claude Fable 5.1: 50.7 (#5), Kimi K2 (Jul 2025): 32.4 (#64)
| Benchmark | Claude Fable 5.1 | Kimi K2 (Jul 2025) |
|---|---|---|
| Terminal-Bench | — | 35.7% |
| APEX-Agents | 68.6% | — |
| Berkeley Function Calling Leaderboard | — | 59.1% |
| Remote Labor Index | 17.9% | — |
| GDP.pdf | 29.6% | — |
| METR Time Horizons | — | 59.2% |
| Vending-Bench 2 | 5,422 | — |
Reasoning Claude Fable 5.1 leads
Claude Fable 5.1: 76.7 (#7), Kimi K2 (Jul 2025): 23.3 (#179)
| Benchmark | Claude Fable 5.1 | Kimi K2 (Jul 2025) |
|---|---|---|
| LMArena Hard Prompts | 1526 | 1384 |
| Epoch Capabilities Index | 164.7 | 146.01 |
| ARC-AGI-2 | 90% | — |
| SimpleBench | — | 26.3% |
| Kagi LLM Benchmark | — | 64.4% |
| NYT Connections (extended) | 90% | — |
| ARC-AGI-1 | 97.5% | — |
| CritPt | 31.1% | — |
| Chess Puzzles | 47% | — |
| EBR-Bench | 57.1% | — |
| Mystery Game Puzzles | 58% | — |
| DTBench | 97.6% | — |
| LMCA | 65.5% | — |
| ForecastBench | — | 60.2 |
Math Claude Fable 5.1 leads
Claude Fable 5.1: 89.6 (#4), Kimi K2 (Jul 2025): 42.7 (#83)
| Benchmark | Claude Fable 5.1 | Kimi K2 (Jul 2025) |
|---|---|---|
| LMArena Math | 1525 | 1397 |
| FrontierMath (Tiers 1-3) | 90.2% | — |
| FrontierMath Tier 4 | 87.8% | — |
| OTIS Mock AIME 2024-2025 | 100% | — |
| ProofBench | 100% | — |
| Omni-MATH | — | 65.4% |
| FrontierMath (Feb 2025 set) | — | 21.4% |
| FrontierMath Erdős | 0% | — |
| FrontierMath Tier 4 (v1) | — | 0% |
Knowledge Claude Fable 5.1 leads
Claude Fable 5.1: 69.6 (#6), Kimi K2 (Jul 2025): 37.3 (#157)
| Benchmark | Claude Fable 5.1 | Kimi K2 (Jul 2025) |
|---|---|---|
| LMArena Expert | 1535 | 1365 |
| Humanity's Last Exam | 46.5% | — |
| SimpleQA Verified | 70.8% | — |
| MMLU-Pro | — | 81.9% |
| Confabulations | — | 20.4% |
| Vectara Hallucination Rate | — | 17.9% |
| GPQA (HELM) | — | 65.3% |
Multimodal Not comparable
Claude Fable 5.1: 53.9 (#4), Kimi K2 (Jul 2025): —
| Benchmark | Claude Fable 5.1 | Kimi K2 (Jul 2025) |
|---|---|---|
| LMArena Vision | 1318 | — |
| Blueprint-Bench 2 | 41.9% | — |
| Furniture Assembly | 70% | — |
| LMArena Document | 1513 | — |
Multilingual Claude Fable 5.1 leads
Claude Fable 5.1: 59.1 (#3), Kimi K2 (Jul 2025): 49.6 (#130)
| Benchmark | Claude Fable 5.1 | Kimi K2 (Jul 2025) |
|---|---|---|
| LMArena Non-English | 1507 | 1372 |
| LMArena Chinese | 1586 | 1415 |
| LMArena French | 1525 | 1379 |
| LMArena German | 1500 | 1387 |
| LMArena Japanese | 1543 | 1349 |
| LMArena Korean | 1534 | 1325 |
| LMArena Russian | 1521 | 1385 |
| LMArena Spanish | 1516 | 1386 |
Instruction Following Claude Fable 5.1 leads
Claude Fable 5.1: 79.2 (#6), Kimi K2 (Jul 2025): 71.1 (#156)
| Benchmark | Claude Fable 5.1 | Kimi K2 (Jul 2025) |
|---|---|---|
| LMArena Instruction Following | 1517 | 1348 |
| IFEval | — | 85% |
Long Context Claude Fable 5.1 leads
Claude Fable 5.1: 46.7 (#20), Kimi K2 (Jul 2025): 41.2 (#145)
| Benchmark | Claude Fable 5.1 | Kimi K2 (Jul 2025) |
|---|---|---|
| LMArena Longer Query | 1522 | 1353 |
| Fiction.LiveBench | — | 66.7% |
| CL-bench | — | 17.6% |
Writing & Preference Claude Fable 5.1 leads
Claude Fable 5.1: 79.2 (#2), Kimi K2 (Jul 2025): 62.3 (#78)
| Benchmark | Claude Fable 5.1 | Kimi K2 (Jul 2025) |
|---|---|---|
| LMArena Text | 1510 | 1380 |
| LMArena Creative Writing | 1507 | 1350 |
| EQ-Bench Creative Writing | 2162 | 1666 |
| LMArena Multi-Turn | 1492 | 1371 |
| Short-Story Creative Writing | — | 85.6% |
| WildBench | — | 86.2% |
Frequently asked questions
Is Claude Fable 5.1 better than Kimi K2 (Jul 2025)?
Claude Fable 5.1 is the stronger model overall, scoring 69.0 to 41.2 on the Noometry Index. Kimi K2 (Jul 2025) costs 20× less per token, which makes it the better buy when Claude Fable 5.1's lead doesn't matter for your workload.
Which is cheaper, Claude Fable 5.1 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; Claude Fable 5.1 lists at $10 and $50.
Is Claude Fable 5.1 or Kimi K2 (Jul 2025) better for coding?
Claude Fable 5.1 scores higher on coding benchmarks: 74.7 versus 42.4 in the Noometry coding category.
Which has the bigger context window?
Claude Fable 5.1 does, with 1M tokens against 262K.
How many benchmarks do Claude Fable 5.1 and Kimi K2 (Jul 2025) share?
22 benchmarks have published results for both models. Claude Fable 5.1 has 52 scored results on Noometry and Kimi K2 (Jul 2025) has 42.