Model comparison
Claude 2.1 vs Claude Fable 5.1
Claude Fable 5.1 is the stronger model overall, scoring 69.0 to 25.2 on the Noometry Index.
Last verified . 4 shared benchmarks.
Summary
- They share 4 benchmarks with published results for both. Claude 2.1 scores higher in 0 categories and Claude Fable 5.1 in 4 categories; 4 gaps are clear of the uncertainty.
- The widest gap is in math, where Claude Fable 5.1 leads 89.6 to 10.2.
- The biggest single-benchmark swing is OTIS Mock AIME 2024-2025: 1.9% for Claude 2.1 and 100% for Claude Fable 5.1.
Side by side
| Claude 2.1 | Claude Fable 5.1 | |
|---|---|---|
| Provider | Anthropic | Anthropic |
| Noometry Index | 25.2 | 69.0 |
| Released | 2023-11-21 | 2026-09-01 |
| Weights | Proprietary | Proprietary |
| Context window | — | 1M |
| Max output | — | 128K |
| Input $ / M tokens | — | $10 |
| Output $ / M tokens | — | $50 |
| Results tracked | 7 | 52 |
Sponsored placements are available on pages like this one. Advertise on Noometry
Category by category
Coding Claude Fable 5.1 leads
Claude 2.1: 26.2 (#327), Claude Fable 5.1: 74.7 (#1)
| Benchmark | Claude 2.1 | Claude Fable 5.1 |
|---|---|---|
| WeirdML | 7.1% | 92.9% |
| FrontierCode | — | 50.9% |
| CursorBench | — | 51.8% |
| LMArena WebDev | — | 1744 |
| FrontierSWE | — | 56.3% |
| SciCode | — | 63.1% |
| GSO | — | 88.2% |
| LMArena Coding | — | 1528 |
| MirrorCode | — | 73.3% |
| ALE-Bench | — | 2,143 |
Agentic & Tool Use Not comparable
Claude 2.1: —, Claude Fable 5.1: 50.7 (#5)
| Benchmark | Claude 2.1 | 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 2.1: 21.4 (#221), Claude Fable 5.1: 76.7 (#7)
| Benchmark | Claude 2.1 | Claude Fable 5.1 |
|---|---|---|
| DTBench | 51% | 97.6% |
| Epoch Capabilities Index | 119.27 | 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% |
| LMArena Hard Prompts | — | 1526 |
| Mystery Game Puzzles | — | 58% |
| LMCA | — | 65.5% |
| ForecastBench | 54.2 | — |
Math Claude Fable 5.1 leads
Claude 2.1: 10.2 (#315), Claude Fable 5.1: 89.6 (#4)
| Benchmark | Claude 2.1 | Claude Fable 5.1 |
|---|---|---|
| OTIS Mock AIME 2024-2025 | 1.9% | 100% |
| FrontierMath (Tiers 1-3) | — | 90.2% |
| FrontierMath Tier 4 | — | 87.8% |
| ProofBench | — | 100% |
| LMArena Math | — | 1525 |
| FrontierMath Erdős | — | 0% |
Knowledge Claude Fable 5.1 leads
Claude 2.1: 15.4 (#292), Claude Fable 5.1: 69.6 (#6)
| Benchmark | Claude 2.1 | Claude Fable 5.1 |
|---|---|---|
| GPQA Diamond | 33% | — |
| Humanity's Last Exam | — | 46.5% |
| SimpleQA Verified | — | 70.8% |
| LMArena Expert | — | 1535 |
| MMLU | 73.5% | — |
Multimodal Not comparable
Claude 2.1: —, Claude Fable 5.1: 53.9 (#4)
| Benchmark | Claude 2.1 | Claude Fable 5.1 |
|---|---|---|
| LMArena Vision | — | 1318 |
| Blueprint-Bench 2 | — | 41.9% |
| Furniture Assembly | — | 70% |
| LMArena Document | — | 1513 |
Multilingual Not comparable
Claude 2.1: —, Claude Fable 5.1: 59.1 (#3)
| Benchmark | Claude 2.1 | Claude Fable 5.1 |
|---|---|---|
| LMArena Non-English | — | 1507 |
| LMArena Chinese | — | 1586 |
| LMArena French | — | 1525 |
| LMArena German | — | 1500 |
| LMArena Japanese | — | 1543 |
| LMArena Korean | — | 1534 |
| LMArena Russian | — | 1521 |
| LMArena Spanish | — | 1516 |
Instruction Following Not comparable
Claude 2.1: —, Claude Fable 5.1: 79.2 (#6)
| Benchmark | Claude 2.1 | Claude Fable 5.1 |
|---|---|---|
| LMArena Instruction Following | — | 1517 |
Long Context Not comparable
Claude 2.1: —, Claude Fable 5.1: 46.7 (#20)
| Benchmark | Claude 2.1 | Claude Fable 5.1 |
|---|---|---|
| LMArena Longer Query | — | 1522 |
Writing & Preference Not comparable
Claude 2.1: —, Claude Fable 5.1: 79.2 (#2)
| Benchmark | Claude 2.1 | Claude Fable 5.1 |
|---|---|---|
| LMArena Text | — | 1510 |
| LMArena Creative Writing | — | 1507 |
| EQ-Bench Creative Writing | — | 2162 |
| LMArena Multi-Turn | — | 1492 |
Frequently asked questions
Is Claude 2.1 better than Claude Fable 5.1?
Claude Fable 5.1 is the stronger model overall, scoring 69.0 to 25.2 on the Noometry Index.
Is Claude 2.1 or Claude Fable 5.1 better for coding?
Claude Fable 5.1 scores higher on coding benchmarks: 74.7 versus 26.2 in the Noometry coding category.
How many benchmarks do Claude 2.1 and Claude Fable 5.1 share?
4 benchmarks have published results for both models. Claude 2.1 has 7 scored results on Noometry and Claude Fable 5.1 has 52.