Model comparison
Claude Fable 5.1 vs o3-mini
Claude Fable 5.1 is the stronger model overall, scoring 69.0 to 36.7 on the Noometry Index. o3-mini costs 10× less per token, which makes it the better buy when Claude Fable 5.1's lead doesn't matter for your workload.
Last verified . 32 shared benchmarks.
Summary
- They share 32 benchmarks with published results for both. Claude Fable 5.1 scores higher in 9 categories and o3-mini in 0 categories; 9 gaps are clear of the uncertainty.
- The widest gap is in math, where Claude Fable 5.1 leads 89.6 to 28.1.
- The biggest single-benchmark swing is FrontierMath Tier 4: 87.8% for Claude Fable 5.1 and 0% for o3-mini.
- o3-mini is cheaper at $1.10 / $4.40 per million input/output tokens, against $10 / $50 for Claude Fable 5.1.
- Claude Fable 5.1 accepts more context: 1M tokens versus 200K.
Side by side
| Claude Fable 5.1 | o3-mini | |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Noometry Index | 69.0 | 36.7 |
| Released | 2026-09-01 | 2024-12-20 |
| Weights | Proprietary | Proprietary |
| Context window | 1M | 200K |
| Max output | 128K | 100K |
| Input $ / M tokens | $10 | $1.10 |
| Output $ / M tokens | $50 | $4.40 |
| Results tracked | 52 | 51 |
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Category by category
Coding Claude Fable 5.1 leads
Claude Fable 5.1: 74.7 (#1), o3-mini: 40.8 (#132)
| Benchmark | Claude Fable 5.1 | o3-mini |
|---|---|---|
| SciCode | 63.1% | 39.8% |
| GSO | 88.2% | 1.3% |
| WeirdML | 92.9% | 43.7% |
| LMArena Coding | 1528 | 1378 |
| FrontierCode | 50.9% | — |
| Aider Polyglot | — | 60.4% |
| CursorBench | 51.8% | — |
| LMArena WebDev | 1744 | — |
| FrontierSWE | 56.3% | — |
| LiveBench Coding | — | 82.7% |
| MirrorCode | 73.3% | — |
| CadEval | — | 54% |
| ALE-Bench | 2,143 | — |
Agentic & Tool Use Claude Fable 5.1 leads
Claude Fable 5.1: 50.7 (#5), o3-mini: 29.6 (#84)
| Benchmark | Claude Fable 5.1 | o3-mini |
|---|---|---|
| APEX-Agents | 68.6% | — |
| Remote Labor Index | 17.9% | — |
| Cybench | — | 22.5% |
| GDP.pdf | 29.6% | — |
| Vending-Bench 2 | 5,422 | — |
Reasoning Claude Fable 5.1 leads
Claude Fable 5.1: 76.7 (#7), o3-mini: 16.3 (#305)
| Benchmark | Claude Fable 5.1 | o3-mini |
|---|---|---|
| ARC-AGI-2 | 90% | 3% |
| ARC-AGI-1 | 97.5% | 34.5% |
| CritPt | 31.1% | 0.3% |
| Chess Puzzles | 47% | 17% |
| LMArena Hard Prompts | 1526 | 1366 |
| Mystery Game Puzzles | 58% | 7% |
| DTBench | 97.6% | 68.8% |
| LMCA | 65.5% | 19% |
| Epoch Capabilities Index | 164.7 | 140.34 |
| SimpleBench | — | 22.8% |
| NYT Connections (extended) | 90% | — |
| EBR-Bench | 57.1% | — |
| LiveBench Reasoning | — | 89.6% |
| LiveBench Data Analysis | — | 70.6% |
| ForecastBench | — | 59.6 |
| LiveBench | — | 75.9% |
Math Claude Fable 5.1 leads
Claude Fable 5.1: 89.6 (#4), o3-mini: 28.1 (#244)
| Benchmark | Claude Fable 5.1 | o3-mini |
|---|---|---|
| FrontierMath (Tiers 1-3) | 90.2% | 18.6% |
| FrontierMath Tier 4 | 87.8% | 0% |
| OTIS Mock AIME 2024-2025 | 100% | 76.9% |
| LMArena Math | 1525 | 1396 |
| ProofBench | 100% | — |
| LiveBench Math | — | 77.3% |
| MATH Level 5 | — | 96.5% |
| FrontierMath (Feb 2025 set) | — | 12.4% |
| FrontierMath Erdős | 0% | — |
| FrontierMath Tier 4 (v1) | — | 4.2% |
Knowledge Claude Fable 5.1 leads
Claude Fable 5.1: 69.6 (#6), o3-mini: 38.3 (#146)
| Benchmark | Claude Fable 5.1 | o3-mini |
|---|---|---|
| SimpleQA Verified | 70.8% | 15.3% |
| LMArena Expert | 1535 | 1364 |
| GPQA Diamond | — | 77% |
| Humanity's Last Exam | 46.5% | — |
| Confabulations | — | 17.9% |
Multimodal Not comparable
Claude Fable 5.1: 53.9 (#4), o3-mini: —
| Benchmark | Claude Fable 5.1 | o3-mini |
|---|---|---|
| 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), o3-mini: 45.7 (#164)
| Benchmark | Claude Fable 5.1 | o3-mini |
|---|---|---|
| LMArena Non-English | 1507 | 1319 |
| LMArena Chinese | 1586 | 1379 |
| LMArena French | 1525 | 1334 |
| LMArena German | 1500 | 1303 |
| LMArena Japanese | 1543 | 1286 |
| LMArena Korean | 1534 | 1314 |
| LMArena Russian | 1521 | 1304 |
| LMArena Spanish | 1516 | 1321 |
Instruction Following Claude Fable 5.1 leads
Claude Fable 5.1: 79.2 (#6), o3-mini: 75.1 (#72)
| Benchmark | Claude Fable 5.1 | o3-mini |
|---|---|---|
| LMArena Instruction Following | 1517 | 1337 |
| LiveBench Instruction Following | — | 84.4% |
Long Context Claude Fable 5.1 leads
Claude Fable 5.1: 46.7 (#20), o3-mini: 33.8 (#256)
| Benchmark | Claude Fable 5.1 | o3-mini |
|---|---|---|
| LMArena Longer Query | 1522 | 1343 |
| Fiction.LiveBench | — | 50% |
Writing & Preference Claude Fable 5.1 leads
Claude Fable 5.1: 79.2 (#2), o3-mini: 50.3 (#182)
| Benchmark | Claude Fable 5.1 | o3-mini |
|---|---|---|
| LMArena Text | 1510 | 1337 |
| LMArena Creative Writing | 1507 | 1286 |
| LMArena Multi-Turn | 1492 | 1320 |
| Short-Story Creative Writing | — | 61.7% |
| EQ-Bench Creative Writing | 2162 | — |
| LiveBench Language | — | 50.7% |
Frequently asked questions
Is Claude Fable 5.1 better than o3-mini?
Claude Fable 5.1 is the stronger model overall, scoring 69.0 to 36.7 on the Noometry Index. o3-mini costs 10× 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 o3-mini?
o3-mini is cheaper. It lists at $1.10 per million input tokens and $4.40 per million output tokens; Claude Fable 5.1 lists at $10 and $50.
Is Claude Fable 5.1 or o3-mini better for coding?
Claude Fable 5.1 scores higher on coding benchmarks: 74.7 versus 40.8 in the Noometry coding category.
Which has the bigger context window?
Claude Fable 5.1 does, with 1M tokens against 200K.
How many benchmarks do Claude Fable 5.1 and o3-mini share?
32 benchmarks have published results for both models. Claude Fable 5.1 has 52 scored results on Noometry and o3-mini has 51.