Model comparison
Claude Fable 5.1 vs GPT-4.1 nano
Claude Fable 5.1 is the stronger model overall, scoring 69.0 to 27.9 on the Noometry Index. GPT-4.1 nano costs 114× less per token, which makes it the better buy when Claude Fable 5.1's lead doesn't matter for your workload.
Last verified . 26 shared benchmarks.
Summary
- They share 26 benchmarks with published results for both. Claude Fable 5.1 scores higher in 10 categories and GPT-4.1 nano in 0 categories; 10 gaps are clear of the uncertainty.
- The widest gap is in reasoning, where Claude Fable 5.1 leads 76.7 to 8.5.
- The biggest single-benchmark swing is ARC-AGI-1: 97.5% for Claude Fable 5.1 and 0% for GPT-4.1 nano.
- GPT-4.1 nano is cheaper at $0.10 / $0.40 per million input/output tokens, against $10 / $50 for Claude Fable 5.1.
- GPT-4.1 nano accepts more context: 1.05M tokens versus 1M.
Side by side
| Claude Fable 5.1 | GPT-4.1 nano | |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Noometry Index | 69.0 | 27.9 |
| Released | 2026-09-01 | 2025-04-14 |
| Weights | Proprietary | Proprietary |
| Context window | 1M | 1.05M |
| Max output | 128K | 33K |
| Input $ / M tokens | $10 | $0.10 |
| Output $ / M tokens | $50 | $0.40 |
| Results tracked | 52 | 38 |
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Category by category
Coding Claude Fable 5.1 leads
Claude Fable 5.1: 74.7 (#1), GPT-4.1 nano: 24.1 (#330)
| Benchmark | Claude Fable 5.1 | GPT-4.1 nano |
|---|---|---|
| SciCode | 63.1% | 25.9% |
| WeirdML | 92.9% | 19% |
| LMArena Coding | 1528 | 1306 |
| FrontierCode | 50.9% | — |
| Aider Polyglot | — | 8.9% |
| CursorBench | 51.8% | — |
| LMArena WebDev | 1744 | — |
| FrontierSWE | 56.3% | — |
| GSO | 88.2% | — |
| MirrorCode | 73.3% | — |
| ALE-Bench | 2,143 | — |
Agentic & Tool Use Claude Fable 5.1 leads
Claude Fable 5.1: 50.7 (#5), GPT-4.1 nano: 26.5 (#104)
| Benchmark | Claude Fable 5.1 | GPT-4.1 nano |
|---|---|---|
| APEX-Agents | 68.6% | — |
| Berkeley Function Calling Leaderboard | — | 33% |
| Remote Labor Index | 17.9% | — |
| GDP.pdf | 29.6% | — |
| Vending-Bench 2 | 5,422 | — |
Reasoning Claude Fable 5.1 leads
Claude Fable 5.1: 76.7 (#7), GPT-4.1 nano: 8.5 (#349)
| Benchmark | Claude Fable 5.1 | GPT-4.1 nano |
|---|---|---|
| ARC-AGI-2 | 90% | 0% |
| ARC-AGI-1 | 97.5% | 0% |
| CritPt | 31.1% | 0% |
| LMArena Hard Prompts | 1526 | 1286 |
| DTBench | 97.6% | 52.5% |
| LMCA | 65.5% | 5.5% |
| Epoch Capabilities Index | 164.7 | 129.62 |
| Kagi LLM Benchmark | — | 33.3% |
| NYT Connections (extended) | 90% | — |
| Chess Puzzles | 47% | — |
| EBR-Bench | 57.1% | — |
| Mystery Game Puzzles | 58% | — |
Math Claude Fable 5.1 leads
Claude Fable 5.1: 89.6 (#4), GPT-4.1 nano: 26.9 (#252)
| Benchmark | Claude Fable 5.1 | GPT-4.1 nano |
|---|---|---|
| OTIS Mock AIME 2024-2025 | 100% | 28.9% |
| LMArena Math | 1525 | 1274 |
| FrontierMath (Tiers 1-3) | 90.2% | — |
| FrontierMath Tier 4 | 87.8% | — |
| ProofBench | 100% | — |
| Omni-MATH | — | 36.7% |
| MATH Level 5 | — | 70% |
| FrontierMath (Feb 2025 set) | — | 1% |
| FrontierMath Erdős | 0% | — |
Knowledge Claude Fable 5.1 leads
Claude Fable 5.1: 69.6 (#6), GPT-4.1 nano: 21.8 (#273)
| Benchmark | Claude Fable 5.1 | GPT-4.1 nano |
|---|---|---|
| SimpleQA Verified | 70.8% | 6% |
| LMArena Expert | 1535 | 1272 |
| GPQA Diamond | — | 48.9% |
| Humanity's Last Exam | 46.5% | — |
| MMLU-Pro | — | 55% |
| GPQA (HELM) | — | 50.7% |
Multimodal Claude Fable 5.1 leads
Claude Fable 5.1: 53.9 (#4), GPT-4.1 nano: 29.2 (#113)
| Benchmark | Claude Fable 5.1 | GPT-4.1 nano |
|---|---|---|
| LMArena Vision | 1318 | 1063 |
| Blueprint-Bench 2 | 41.9% | — |
| Furniture Assembly | 70% | — |
| LMArena Document | 1513 | — |
Multilingual Claude Fable 5.1 leads
Claude Fable 5.1: 59.1 (#3), GPT-4.1 nano: 41.6 (#205)
| Benchmark | Claude Fable 5.1 | GPT-4.1 nano |
|---|---|---|
| LMArena Non-English | 1507 | 1260 |
| LMArena Chinese | 1586 | 1270 |
| LMArena German | 1500 | 1288 |
| LMArena Japanese | 1543 | 1198 |
| LMArena Russian | 1521 | 1261 |
| LMArena French | 1525 | — |
| LMArena Korean | 1534 | — |
| LMArena Spanish | 1516 | — |
Instruction Following Claude Fable 5.1 leads
Claude Fable 5.1: 79.2 (#6), GPT-4.1 nano: 67.8 (#193)
| Benchmark | Claude Fable 5.1 | GPT-4.1 nano |
|---|---|---|
| LMArena Instruction Following | 1517 | 1267 |
| IFEval | — | 84.3% |
Long Context Claude Fable 5.1 leads
Claude Fable 5.1: 46.7 (#20), GPT-4.1 nano: 23.7 (#296)
| Benchmark | Claude Fable 5.1 | GPT-4.1 nano |
|---|---|---|
| LMArena Longer Query | 1522 | 1283 |
| Fiction.LiveBench | — | 25% |
Writing & Preference Claude Fable 5.1 leads
Claude Fable 5.1: 79.2 (#2), GPT-4.1 nano: 40.5 (#243)
| Benchmark | Claude Fable 5.1 | GPT-4.1 nano |
|---|---|---|
| LMArena Text | 1510 | 1285 |
| LMArena Creative Writing | 1507 | 1260 |
| EQ-Bench Creative Writing | 2162 | 946 |
| LMArena Multi-Turn | 1492 | 1277 |
| WildBench | — | 81.2% |
Frequently asked questions
Is Claude Fable 5.1 better than GPT-4.1 nano?
Claude Fable 5.1 is the stronger model overall, scoring 69.0 to 27.9 on the Noometry Index. GPT-4.1 nano costs 114× 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-4.1 nano?
GPT-4.1 nano is cheaper. It lists at $0.10 per million input tokens and $0.40 per million output tokens; Claude Fable 5.1 lists at $10 and $50.
Is Claude Fable 5.1 or GPT-4.1 nano better for coding?
Claude Fable 5.1 scores higher on coding benchmarks: 74.7 versus 24.1 in the Noometry coding category.
Which has the bigger context window?
GPT-4.1 nano does, with 1.05M tokens against 1M.
How many benchmarks do Claude Fable 5.1 and GPT-4.1 nano share?
26 benchmarks have published results for both models. Claude Fable 5.1 has 52 scored results on Noometry and GPT-4.1 nano has 38.