Model comparison
Claude Fable 5 vs GPT-5.5 Instant
Claude Fable 5 is the stronger model overall, scoring 66.8 to 42.7 on the Noometry Index.
Last verified . 27 shared benchmarks.
Summary
- They share 27 benchmarks with published results for both. Claude Fable 5 scores higher in 9 categories and GPT-5.5 Instant in 0 categories; 9 gaps are clear of the uncertainty.
- The widest gap is in math, where Claude Fable 5 leads 88.5 to 26.5.
- The biggest single-benchmark swing is FrontierMath Tier 4: 90.2% for Claude Fable 5 and 2.4% for GPT-5.5 Instant.
Side by side
| Claude Fable 5 | GPT-5.5 Instant | |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Noometry Index | 66.8 | 42.7 |
| Released | 2026-06-07 | 2026-05-05 |
| Weights | Proprietary | Proprietary |
| Context window | 1M | — |
| Max output | 128K | — |
| Input $ / M tokens | $10 | — |
| Output $ / M tokens | $50 | — |
| Results tracked | 62 | 27 |
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Category by category
Coding Claude Fable 5 leads
Claude Fable 5: 70.6 (#4), GPT-5.5 Instant: 44.3 (#74)
| Benchmark | Claude Fable 5 | GPT-5.5 Instant |
|---|---|---|
| SciCode | 61% | 48.6% |
| LMArena Coding | 1519 | 1433 |
| DeepSWE | 69.9% | — |
| FrontierCode | 53.5% | — |
| LMArena WebDev | 1625 | — |
| FrontierSWE | 47% | — |
| GSO | 78.4% | — |
| WeirdML | 91.9% | — |
| MirrorCode | 63.9% | — |
| ALE-Bench | 2,041 | — |
Agentic & Tool Use Not comparable
Claude Fable 5: 54.0 (#2), GPT-5.5 Instant: —
| Benchmark | Claude Fable 5 | GPT-5.5 Instant |
|---|---|---|
| APEX-Agents | 63.6% | — |
| 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-5.5 Instant: 24.9 (#155)
| Benchmark | Claude Fable 5 | GPT-5.5 Instant |
|---|---|---|
| CritPt | 28.6% | 0% |
| Chess Puzzles | 41% | 12% |
| LMArena Hard Prompts | 1508 | 1426 |
| Epoch Capabilities Index | 162.06 | 142.52 |
| ARC-AGI-2 | 89.2% | — |
| SimpleBench | 81.9% | — |
| Kagi LLM Benchmark | 91.4% | — |
| NYT Connections (extended) | 92.7% | — |
| ARC-AGI-1 | 98.5% | — |
| EnigmaEval | 39.3% | — |
| EBR-Bench | 39.5% | — |
| Mystery Game Puzzles | 52% | — |
| DTBench | 98.4% | — |
| LMCA | 61.1% | — |
| Surface Evolver Bench | 95% | — |
| Bench to the Future 3 | 0.13 | — |
Math Claude Fable 5 leads
Claude Fable 5: 88.5 (#5), GPT-5.5 Instant: 26.5 (#259)
| Benchmark | Claude Fable 5 | GPT-5.5 Instant |
|---|---|---|
| FrontierMath (Tiers 1-3) | 87% | 26.3% |
| FrontierMath Tier 4 | 90.2% | 2.4% |
| OTIS Mock AIME 2024-2025 | 100% | 68.1% |
| LMArena Math | 1519 | 1420 |
| ProofBench | 95% | — |
| FrontierMath Erdős | 0% | — |
Knowledge Claude Fable 5 leads
Claude Fable 5: 62.2 (#25), GPT-5.5 Instant: 48.9 (#74)
| Benchmark | Claude Fable 5 | GPT-5.5 Instant |
|---|---|---|
| GPQA Diamond | 85.9% | 82.5% |
| LMArena Expert | 1534 | 1409 |
| SimpleQA Verified | 70.7% | — |
Multimodal Claude Fable 5 leads
Claude Fable 5: 45.3 (#17), GPT-5.5 Instant: 40.0 (#52)
| Benchmark | Claude Fable 5 | GPT-5.5 Instant |
|---|---|---|
| LMArena Vision | 1324 | 1250 |
| LMArena Document | 1496 | 1403 |
| Blueprint-Bench 2 | 38.6% | — |
| Furniture Assembly | 35.8% | — |
Multilingual Claude Fable 5 leads
Claude Fable 5: 57.3 (#9), GPT-5.5 Instant: 52.8 (#80)
| Benchmark | Claude Fable 5 | GPT-5.5 Instant |
|---|---|---|
| LMArena Non-English | 1481 | 1417 |
| LMArena Chinese | 1543 | 1456 |
| LMArena French | 1505 | 1428 |
| LMArena German | 1486 | 1411 |
| LMArena Japanese | 1506 | 1408 |
| LMArena Korean | 1488 | 1392 |
| LMArena Russian | 1504 | 1431 |
| LMArena Spanish | 1498 | 1429 |
Instruction Following Claude Fable 5 leads
Claude Fable 5: 78.6 (#8), GPT-5.5 Instant: 74.2 (#100)
| Benchmark | Claude Fable 5 | GPT-5.5 Instant |
|---|---|---|
| LMArena Instruction Following | 1502 | 1406 |
Long Context Claude Fable 5 leads
Claude Fable 5: 46.3 (#23), GPT-5.5 Instant: 43.4 (#96)
| Benchmark | Claude Fable 5 | GPT-5.5 Instant |
|---|---|---|
| LMArena Longer Query | 1509 | 1422 |
Writing & Preference Claude Fable 5 leads
Claude Fable 5: 75.9 (#5), GPT-5.5 Instant: 61.8 (#85)
| Benchmark | Claude Fable 5 | GPT-5.5 Instant |
|---|---|---|
| LMArena Text | 1491 | 1419 |
| LMArena Creative Writing | 1494 | 1419 |
| LMArena Multi-Turn | 1504 | 1433 |
| EQ-Bench Creative Writing | 1943 | — |
| EQ-Bench 4 | 1340 | — |
Frequently asked questions
Is Claude Fable 5 better than GPT-5.5 Instant?
Claude Fable 5 is the stronger model overall, scoring 66.8 to 42.7 on the Noometry Index.
Is Claude Fable 5 or GPT-5.5 Instant better for coding?
Claude Fable 5 scores higher on coding benchmarks: 70.6 versus 44.3 in the Noometry coding category.
How many benchmarks do Claude Fable 5 and GPT-5.5 Instant share?
27 benchmarks have published results for both models. Claude Fable 5 has 62 scored results on Noometry and GPT-5.5 Instant has 27.