Model comparison
Claude Fable 5.1 vs GPT-5.1
Claude Fable 5.1 is the stronger model overall, scoring 68.5 to 48.8 on the Noometry Index. GPT-5.1 costs 5.8× less per token, which makes it the better buy when Claude Fable 5.1's lead doesn't matter for your workload.
Last verified . 34 shared benchmarks.
Summary
- They share 34 benchmarks with published results for both. Claude Fable 5.1 scores higher in 8 categories and GPT-5.1 in 2 categories; 9 gaps are clear of the uncertainty.
- The widest gap is in math, where Claude Fable 5.1 leads 89.5 to 50.3.
- The biggest single-benchmark swing is ARC-AGI-2: 90% for Claude Fable 5.1 and 17.6% for GPT-5.1.
- GPT-5.1 is cheaper at $1.25 / $10 per million input/output tokens, against $10 / $50 for Claude Fable 5.1.
- Claude Fable 5.1 accepts more context: 1M tokens versus 400K.
Side by side
| Claude Fable 5.1 | GPT-5.1 | |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Noometry Index | 68.5 | 48.8 |
| Released | 2026-09-01 | 2025-11-13 |
| Weights | Proprietary | Proprietary |
| Context window | 1M | 400K |
| Max output | 128K | 128K |
| Input $ / M tokens | $10 | $1.25 |
| Output $ / M tokens | $50 | $10 |
| Results tracked | 50 | 63 |
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Category by category
Coding Claude Fable 5.1 leads
Claude Fable 5.1: 70.5 (#2), GPT-5.1: 46.9 (#59)
| Benchmark | Claude Fable 5.1 | GPT-5.1 |
|---|---|---|
| LMArena WebDev | 1753 | 1395 |
| SciCode | 63.1% | 43.3% |
| WeirdML | 92.9% | 60.8% |
| LMArena Coding | 1523 | 1454 |
| ALE-Bench | 2,143 | 1,192 |
| SWE-bench Verified | — | 68% |
| FrontierCode | 50.9% | — |
| SWE-bench Verified (bash only) | — | 66% |
| CursorBench | 51.8% | — |
| FrontierSWE | 56.3% | — |
| GSO | — | 13.7% |
| LiveBench Coding | — | 72.5% |
| MirrorCode | 73.3% | — |
Agentic & Tool Use Claude Fable 5.1 leads
Claude Fable 5.1: 50.8 (#5), GPT-5.1: 32.5 (#55)
| Benchmark | Claude Fable 5.1 | GPT-5.1 |
|---|---|---|
| Vending-Bench 2 | 5,422 | 1,473 |
| Terminal-Bench | — | 47.6% |
| APEX-Agents | 68.6% | — |
| Remote Labor Index | 17.9% | — |
| DeepResearch Bench | — | 42.8% |
| GDP.pdf | 29.6% | — |
| LMArena Search | — | 1199 |
Reasoning Claude Fable 5.1 leads
Claude Fable 5.1: 76.7 (#5), GPT-5.1: 39.9 (#50)
| Benchmark | Claude Fable 5.1 | GPT-5.1 |
|---|---|---|
| ARC-AGI-2 | 90% | 17.6% |
| ARC-AGI-1 | 97.5% | 72.8% |
| CritPt | 31.1% | 4.9% |
| Chess Puzzles | 47% | 32% |
| LMArena Hard Prompts | 1526 | 1457 |
| Mystery Game Puzzles | 58% | 19% |
| DTBench | 97.6% | 90.1% |
| LMCA | 65.5% | 43.9% |
| Epoch Capabilities Index | 165 | 149.66 |
| SimpleBench | — | 53.2% |
| NYT Connections (extended) | 90% | — |
| EnigmaEval | — | 11.2% |
| EBR-Bench | 57.1% | — |
| LiveBench Reasoning | — | 95.8% |
| LiveBench Data Analysis | — | 72.1% |
| ForecastBench | — | 58.1 |
| LiveBench | — | 78.8% |
Math Claude Fable 5.1 leads
Claude Fable 5.1: 89.5 (#3), GPT-5.1: 50.3 (#45)
| Benchmark | Claude Fable 5.1 | GPT-5.1 |
|---|---|---|
| OTIS Mock AIME 2024-2025 | 100% | 88.6% |
| LMArena Math | 1519 | 1446 |
| FrontierMath (Tiers 1-3) | 90.2% | — |
| FrontierMath Tier 4 | 87.8% | — |
| ProofBench | 100% | — |
| Omni-MATH | — | 46.4% |
| LiveBench Math | — | 94.5% |
| FrontierMath (Feb 2025 set) | — | 31% |
| FrontierMath Erdős | 0% | — |
| FrontierMath Tier 4 (v1) | — | 12.5% |
Knowledge Claude Fable 5.1 leads
Claude Fable 5.1: 69.3 (#5), GPT-5.1: 50.5 (#65)
| Benchmark | Claude Fable 5.1 | GPT-5.1 |
|---|---|---|
| Humanity's Last Exam | 46.5% | 23.7% |
| SimpleQA Verified | 70.8% | 48% |
| LMArena Expert | 1528 | 1470 |
| GPQA Diamond | — | 87.6% |
| MMLU-Pro | — | 57.9% |
| Vectara Hallucination Rate | — | 10.9% |
| GPQA (HELM) | — | 44.2% |
Multimodal Claude Fable 5.1 leads
Claude Fable 5.1: 54.1 (#4), GPT-5.1: 44.0 (#17)
| Benchmark | Claude Fable 5.1 | GPT-5.1 |
|---|---|---|
| LMArena Vision | 1319 | 1250 |
| LMArena Document | 1513 | 1403 |
| VPCT | — | 58.7% |
| Blueprint-Bench 2 | 41.9% | — |
| Furniture Assembly | 70% | — |
Multilingual Claude Fable 5.1 leads
Claude Fable 5.1: 59.5 (#2), GPT-5.1: 54.0 (#51)
| Benchmark | Claude Fable 5.1 | GPT-5.1 |
|---|---|---|
| LMArena Non-English | 1509 | 1431 |
| LMArena Chinese | 1589 | 1495 |
| LMArena French | 1532 | 1451 |
| LMArena German | 1495 | 1439 |
| LMArena Japanese | 1565 | 1453 |
| LMArena Russian | 1525 | 1435 |
| LMArena Spanish | 1503 | 1430 |
| LMArena Korean | — | 1401 |
Instruction Following GPT-5.1 leads
Claude Fable 5.1: 79.3 (#6), GPT-5.1: 84.0 (#1)
| Benchmark | Claude Fable 5.1 | GPT-5.1 |
|---|---|---|
| LMArena Instruction Following | 1515 | 1442 |
| LiveBench Instruction Following | — | 93.3% |
| IFEval | — | 93.5% |
Long Context Too close to call
Claude Fable 5.1: 46.8 (#19), GPT-5.1: 47.6 (#14)
| Benchmark | Claude Fable 5.1 | GPT-5.1 |
|---|---|---|
| LMArena Longer Query | 1524 | 1448 |
| CL-bench | — | 23.7% |
| CL-bench Life | — | 17.3% |
Writing & Preference Claude Fable 5.1 leads
Claude Fable 5.1: 79.3 (#1), GPT-5.1: 64.7 (#53)
| Benchmark | Claude Fable 5.1 | GPT-5.1 |
|---|---|---|
| LMArena Text | 1511 | 1443 |
| LMArena Creative Writing | 1507 | 1427 |
| LMArena Multi-Turn | 1492 | 1449 |
| EQ-Bench Creative Writing | 2162 | — |
| WildBench | — | 86.3% |
| LiveBench Language | — | 80.2% |
Frequently asked questions
Is Claude Fable 5.1 better than GPT-5.1?
Claude Fable 5.1 is the stronger model overall, scoring 68.5 to 48.8 on the Noometry Index. GPT-5.1 costs 5.8× 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 GPT-5.1?
GPT-5.1 is cheaper. It lists at $1.25 per million input tokens and $10 per million output tokens; Claude Fable 5.1 lists at $10 and $50.
Is Claude Fable 5.1 or GPT-5.1 better for coding?
Claude Fable 5.1 scores higher on coding benchmarks: 70.5 versus 46.9 in the Noometry coding category.
Which has the bigger context window?
Claude Fable 5.1 does, with 1M tokens against 400K.
How many benchmarks do Claude Fable 5.1 and GPT-5.1 share?
34 benchmarks have published results for both models. Claude Fable 5.1 has 50 scored results on Noometry and GPT-5.1 has 63.