Model comparison
Claude Fable 5 vs GPT-5 Nano
Claude Fable 5 is the stronger model overall, scoring 66.8 to 33.5 on the Noometry Index. GPT-5 Nano costs 145× less per token, which makes it the better buy when Claude Fable 5'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 scores higher in 10 categories and GPT-5 Nano in 0 categories; 10 gaps are clear of the uncertainty.
- The widest gap is in reasoning, where Claude Fable 5 leads 76.8 to 16.3.
- The biggest single-benchmark swing is FrontierMath Tier 4: 90.2% for Claude Fable 5 and 2.4% for GPT-5 Nano.
- GPT-5 Nano is cheaper at $0.05 / $0.40 per million input/output tokens, against $10 / $50 for Claude Fable 5.
- Claude Fable 5 accepts more context: 1M tokens versus 400K.
Side by side
| Claude Fable 5 | GPT-5 Nano | |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Noometry Index | 66.8 | 33.5 |
| Released | 2026-06-07 | 2025-08-07 |
| Weights | Proprietary | Proprietary |
| Context window | 1M | 400K |
| Max output | 128K | 128K |
| Input $ / M tokens | $10 | $0.05 |
| Output $ / M tokens | $50 | $0.40 |
| Results tracked | 62 | 49 |
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Category by category
Coding Claude Fable 5 leads
Claude Fable 5: 70.6 (#4), GPT-5 Nano: 33.6 (#254)
| Benchmark | Claude Fable 5 | GPT-5 Nano |
|---|---|---|
| WeirdML | 91.9% | 38.1% |
| LMArena Coding | 1519 | 1351 |
| ALE-Bench | 2,041 | 718.67 |
| DeepSWE | 69.9% | — |
| FrontierCode | 53.5% | — |
| SWE-bench Verified (bash only) | — | 34.8% |
| LMArena WebDev | 1625 | — |
| FrontierSWE | 47% | — |
| SciCode | 61% | — |
| GSO | 78.4% | — |
| MirrorCode | 63.9% | — |
Agentic & Tool Use Claude Fable 5 leads
Claude Fable 5: 54.0 (#2), GPT-5 Nano: 25.8 (#106)
| Benchmark | Claude Fable 5 | GPT-5 Nano |
|---|---|---|
| Terminal-Bench | — | 21.8% |
| APEX-Agents | 63.6% | — |
| Berkeley Function Calling Leaderboard | — | 51.5% |
| Remote Labor Index | 16.1% | — |
| τ²-bench Banking | 39.7% | — |
| PostTrainBench | 41.8% | — |
| GBAEval | 74.5% | — |
| GDP.pdf | 30% | — |
| LMArena Search | 1230 | — |
| Vending-Bench 2 | 5,680 | — |
Reasoning Claude Fable 5 leads
Claude Fable 5: 76.8 (#6), GPT-5 Nano: 16.3 (#306)
| Benchmark | Claude Fable 5 | GPT-5 Nano |
|---|---|---|
| ARC-AGI-2 | 89.2% | 2.6% |
| Kagi LLM Benchmark | 91.4% | 62.2% |
| ARC-AGI-1 | 98.5% | 20.7% |
| Chess Puzzles | 41% | 27% |
| LMArena Hard Prompts | 1508 | 1328 |
| Mystery Game Puzzles | 52% | 9% |
| DTBench | 98.4% | 62.7% |
| LMCA | 61.1% | 7.9% |
| Epoch Capabilities Index | 162.06 | 139.38 |
| SimpleBench | 81.9% | — |
| NYT Connections (extended) | 92.7% | — |
| CritPt | 28.6% | — |
| EnigmaEval | 39.3% | — |
| EBR-Bench | 39.5% | — |
| Surface Evolver Bench | 95% | — |
| Bench to the Future 3 | 0.13 | — |
| ForecastBench | — | 59.1 |
Math Claude Fable 5 leads
Claude Fable 5: 88.5 (#5), GPT-5 Nano: 29.4 (#241)
| Benchmark | Claude Fable 5 | GPT-5 Nano |
|---|---|---|
| FrontierMath (Tiers 1-3) | 87% | 20% |
| FrontierMath Tier 4 | 90.2% | 2.4% |
| OTIS Mock AIME 2024-2025 | 100% | 81.1% |
| ProofBench | 95% | 12% |
| LMArena Math | 1519 | 1317 |
| Omni-MATH | — | 54.6% |
| MATH Level 5 | — | 95.2% |
| FrontierMath (Feb 2025 set) | — | 8.3% |
| FrontierMath Erdős | 0% | — |
| FrontierMath Tier 4 (v1) | — | 2.1% |
Knowledge Claude Fable 5 leads
Claude Fable 5: 62.2 (#25), GPT-5 Nano: 35.9 (#178)
| Benchmark | Claude Fable 5 | GPT-5 Nano |
|---|---|---|
| GPQA Diamond | 85.9% | 69.4% |
| SimpleQA Verified | 70.7% | 11.7% |
| LMArena Expert | 1534 | 1321 |
| MMLU-Pro | — | 77.8% |
| Vectara Hallucination Rate | — | 10.5% |
| GPQA (HELM) | — | 67.9% |
Multimodal Claude Fable 5 leads
Claude Fable 5: 45.3 (#17), GPT-5 Nano: 31.3 (#108)
| Benchmark | Claude Fable 5 | GPT-5 Nano |
|---|---|---|
| LMArena Vision | 1324 | 1159 |
| VPCT | — | 37.2% |
| Blueprint-Bench 2 | 38.6% | — |
| Furniture Assembly | 35.8% | — |
| LMArena Document | 1496 | — |
Multilingual Claude Fable 5 leads
Claude Fable 5: 57.3 (#9), GPT-5 Nano: 45.3 (#172)
| Benchmark | Claude Fable 5 | GPT-5 Nano |
|---|---|---|
| LMArena Non-English | 1481 | 1313 |
| LMArena Chinese | 1543 | 1356 |
| LMArena German | 1486 | 1327 |
| LMArena Japanese | 1506 | 1226 |
| LMArena Korean | 1488 | 1269 |
| LMArena Russian | 1504 | 1296 |
| LMArena Spanish | 1498 | 1360 |
| LMArena French | 1505 | — |
Instruction Following Claude Fable 5 leads
Claude Fable 5: 78.6 (#8), GPT-5 Nano: 75.0 (#79)
| Benchmark | Claude Fable 5 | GPT-5 Nano |
|---|---|---|
| LMArena Instruction Following | 1502 | 1306 |
| IFEval | — | 93.2% |
Long Context Claude Fable 5 leads
Claude Fable 5: 46.3 (#23), GPT-5 Nano: 31.3 (#281)
| Benchmark | Claude Fable 5 | GPT-5 Nano |
|---|---|---|
| LMArena Longer Query | 1509 | 1312 |
| Fiction.LiveBench | — | 44.4% |
Writing & Preference Claude Fable 5 leads
Claude Fable 5: 75.9 (#5), GPT-5 Nano: 39.1 (#249)
| Benchmark | Claude Fable 5 | GPT-5 Nano |
|---|---|---|
| LMArena Text | 1491 | 1320 |
| LMArena Creative Writing | 1494 | 1249 |
| EQ-Bench Creative Writing | 1943 | 705 |
| LMArena Multi-Turn | 1504 | 1311 |
| WildBench | — | 80.6% |
| EQ-Bench 4 | 1340 | — |
Frequently asked questions
Is Claude Fable 5 better than GPT-5 Nano?
Claude Fable 5 is the stronger model overall, scoring 66.8 to 33.5 on the Noometry Index. GPT-5 Nano costs 145× less per token, which makes it the better buy when Claude Fable 5's lead doesn't matter for your workload.
Which is cheaper, Claude Fable 5 or GPT-5 Nano?
GPT-5 Nano is cheaper. It lists at $0.05 per million input tokens and $0.40 per million output tokens; Claude Fable 5 lists at $10 and $50.
Is Claude Fable 5 or GPT-5 Nano better for coding?
Claude Fable 5 scores higher on coding benchmarks: 70.6 versus 33.6 in the Noometry coding category.
Which has the bigger context window?
Claude Fable 5 does, with 1M tokens against 400K.
How many benchmarks do Claude Fable 5 and GPT-5 Nano share?
34 benchmarks have published results for both models. Claude Fable 5 has 62 scored results on Noometry and GPT-5 Nano has 49.