Model comparison
Claude 3 Sonnet vs Claude Fable 5.1
Claude Fable 5.1 is the stronger model overall, scoring 69.0 to 29.0 on the Noometry Index.
Last verified . 22 shared benchmarks.
Summary
- They share 22 benchmarks with published results for both. Claude 3 Sonnet scores higher in 0 categories and Claude Fable 5.1 in 9 categories; 9 gaps are clear of the uncertainty.
- The widest gap is in math, where Claude Fable 5.1 leads 89.6 to 10.7.
- The biggest single-benchmark swing is OTIS Mock AIME 2024-2025: 2.5% for Claude 3 Sonnet and 100% for Claude Fable 5.1.
Side by side
| Claude 3 Sonnet | Claude Fable 5.1 | |
|---|---|---|
| Provider | Anthropic | Anthropic |
| Noometry Index | 29.0 | 69.0 |
| Released | 2024-02-29 | 2026-09-01 |
| Weights | Proprietary | Proprietary |
| Context window | — | 1M |
| Max output | — | 128K |
| Input $ / M tokens | — | $10 |
| Output $ / M tokens | — | $50 |
| Results tracked | 30 | 52 |
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Category by category
Coding Claude Fable 5.1 leads
Claude 3 Sonnet: 29.6 (#302), Claude Fable 5.1: 74.7 (#1)
| Benchmark | Claude 3 Sonnet | Claude Fable 5.1 |
|---|---|---|
| WeirdML | 10.2% | 92.9% |
| LMArena Coding | 1223 | 1528 |
| FrontierCode | — | 50.9% |
| CursorBench | — | 51.8% |
| LMArena WebDev | — | 1744 |
| FrontierSWE | — | 56.3% |
| SciCode | — | 63.1% |
| GSO | — | 88.2% |
| BigCodeBench Instruct | 42.7% | — |
| MirrorCode | — | 73.3% |
| BigCodeBench Complete | 53.8% | — |
| ALE-Bench | — | 2,143 |
| HumanEval+ | 64% | — |
| MBPP+ | 69.3% | — |
Agentic & Tool Use Not comparable
Claude 3 Sonnet: —, Claude Fable 5.1: 50.7 (#5)
| Benchmark | Claude 3 Sonnet | Claude Fable 5.1 |
|---|---|---|
| APEX-Agents | — | 68.6% |
| Remote Labor Index | — | 17.9% |
| GDP.pdf | — | 29.6% |
| Vending-Bench 2 | — | 5,422 |
Reasoning Claude Fable 5.1 leads
Claude 3 Sonnet: 20.5 (#237), Claude Fable 5.1: 76.7 (#7)
| Benchmark | Claude 3 Sonnet | Claude Fable 5.1 |
|---|---|---|
| LMArena Hard Prompts | 1197 | 1526 |
| DTBench | 53.6% | 97.6% |
| Epoch Capabilities Index | 120.7 | 164.7 |
| ARC-AGI-2 | — | 90% |
| NYT Connections (extended) | — | 90% |
| ARC-AGI-1 | — | 97.5% |
| CritPt | — | 31.1% |
| Chess Puzzles | — | 47% |
| EBR-Bench | — | 57.1% |
| Mystery Game Puzzles | — | 58% |
| LMCA | — | 65.5% |
| WinoGrande | 75.1% | — |
Math Claude Fable 5.1 leads
Claude 3 Sonnet: 10.7 (#310), Claude Fable 5.1: 89.6 (#4)
| Benchmark | Claude 3 Sonnet | Claude Fable 5.1 |
|---|---|---|
| OTIS Mock AIME 2024-2025 | 2.5% | 100% |
| LMArena Math | 1213 | 1525 |
| FrontierMath (Tiers 1-3) | — | 90.2% |
| FrontierMath Tier 4 | — | 87.8% |
| ProofBench | — | 100% |
| MATH Level 5 | 18.2% | — |
| FrontierMath Erdős | — | 0% |
Knowledge Claude Fable 5.1 leads
Claude 3 Sonnet: 21.1 (#276), Claude Fable 5.1: 69.6 (#6)
| Benchmark | Claude 3 Sonnet | Claude Fable 5.1 |
|---|---|---|
| LMArena Expert | 1173 | 1535 |
| GPQA Diamond | 40.6% | — |
| Humanity's Last Exam | — | 46.5% |
| SimpleQA Verified | — | 70.8% |
| MMLU | 75.9% | — |
Multimodal Claude Fable 5.1 leads
Claude 3 Sonnet: 25.2 (#125), Claude Fable 5.1: 53.9 (#4)
| Benchmark | Claude 3 Sonnet | Claude Fable 5.1 |
|---|---|---|
| LMArena Vision | 984 | 1318 |
| Blueprint-Bench 2 | — | 41.9% |
| Furniture Assembly | — | 70% |
| LMArena Document | — | 1513 |
Multilingual Claude Fable 5.1 leads
Claude 3 Sonnet: 37.8 (#234), Claude Fable 5.1: 59.1 (#3)
| Benchmark | Claude 3 Sonnet | Claude Fable 5.1 |
|---|---|---|
| LMArena Non-English | 1205 | 1507 |
| LMArena Chinese | 1189 | 1586 |
| LMArena French | 1229 | 1525 |
| LMArena German | 1204 | 1500 |
| LMArena Japanese | 1131 | 1543 |
| LMArena Korean | 1128 | 1534 |
| LMArena Russian | 1227 | 1521 |
| LMArena Spanish | 1204 | 1516 |
Instruction Following Claude Fable 5.1 leads
Claude 3 Sonnet: 62.8 (#235), Claude Fable 5.1: 79.2 (#6)
| Benchmark | Claude 3 Sonnet | Claude Fable 5.1 |
|---|---|---|
| LMArena Instruction Following | 1199 | 1517 |
Long Context Claude Fable 5.1 leads
Claude 3 Sonnet: 36.7 (#228), Claude Fable 5.1: 46.7 (#20)
| Benchmark | Claude 3 Sonnet | Claude Fable 5.1 |
|---|---|---|
| LMArena Longer Query | 1211 | 1522 |
Writing & Preference Claude Fable 5.1 leads
Claude 3 Sonnet: 42.1 (#238), Claude Fable 5.1: 79.2 (#2)
| Benchmark | Claude 3 Sonnet | Claude Fable 5.1 |
|---|---|---|
| LMArena Text | 1218 | 1510 |
| LMArena Creative Writing | 1186 | 1507 |
| LMArena Multi-Turn | 1227 | 1492 |
| EQ-Bench Creative Writing | — | 2162 |
Frequently asked questions
Is Claude 3 Sonnet better than Claude Fable 5.1?
Claude Fable 5.1 is the stronger model overall, scoring 69.0 to 29.0 on the Noometry Index.
Is Claude 3 Sonnet or Claude Fable 5.1 better for coding?
Claude Fable 5.1 scores higher on coding benchmarks: 74.7 versus 29.6 in the Noometry coding category.
How many benchmarks do Claude 3 Sonnet and Claude Fable 5.1 share?
22 benchmarks have published results for both models. Claude 3 Sonnet has 30 scored results on Noometry and Claude Fable 5.1 has 52.