Claude Fable 5.1 vs Claude Opus 5.5
Claude Fable 5.1 (Anthropic) and Claude Opus 5.5 (Anthropic) compared on benchmarks, pricing, context window, and use-case rankings.
- Claude Opus 5.5 leads on overall intelligence (ECI 169 vs 166).
- Claude Opus 5.5 is cheaper on input tokens: $4.00 vs $10.00 per 1M.
- Claude Opus 5.5 ranks higher for coding (100th vs 98th percentile).
| Attribute | Claude Fable 5.1 | Claude Opus 5.5 |
|---|---|---|
| Scores | ||
| Intelligence (ECI) | 166 | 169 |
| Coding | 98 | 100 |
| Math | 87 | 87 |
| Reasoning & Knowledge | 91 | 90 |
| Agentic & Tools | 95 | 97 |
| Specifications | ||
| Developer | Anthropic | Anthropic |
| Family | Claude | Claude |
| Released | Sep 1, 2026 | Sep 22, 2026 |
| Parameters | — | — |
| Availability | API access | API access |
| Context window | 1M | 1M |
| Price — $/M input | $10.00 | $4.00 |
| Price — $/M output | $50.00 | $20.00 |
| Inputs | text, image, file | text, image, file |
| Outputs | text | text |
| Benchmarks | ||
| AIME 2024/2025 | 100% | 100% |
| APEX | 69% | 74% |
| ARC-AGI | 98% | 99% |
| ARC-AGI-2 | 90% | 93% |
| GPQA Diamond | 94% | 91% |
| GSO (code optimization) | 88% | — |
| Humanity's Last Exam | 47% | 61% |
| SciCode | 63% | 67% |
| SimpleQA Verified | 71% | 72% |
| WebDev Arena | 1758 | 1820 |
| WeirdML | 93% | — |
Use-case scores are 0–100 percentile composites across each area’s benchmarks, ranked against every model from the past year. Highlighted cells lead each row. Open a model for the full picture.
Frequently asked questions
Is Claude Fable 5.1 better than Claude Opus 5.5?
On Epoch AI's Capabilities Index, Claude Opus 5.5 scores higher (169) than Claude Fable 5.1 (166). The right pick depends on your task, so compare their coding, math, and reasoning scores in the table above.
Which is cheaper, Claude Fable 5.1 or Claude Opus 5.5?
Claude Opus 5.5 is cheaper on input tokens at $4.00 per million, versus $10.00 (representative OpenRouter pricing).
Which has a larger context window, Claude Fable 5.1 or Claude Opus 5.5?
Neither: both support up to 1M tokens.
Which is better for coding, Claude Fable 5.1 or Claude Opus 5.5?
Claude Opus 5.5 ranks higher across coding benchmarks like WebDev Arena and SciCode: 100th vs 98th percentile among the models tracked on Model Beat.
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Benchmarks & model data from Epoch AI (CC BY); pricing & specs from OpenRouter. ECI = Epoch Capabilities Index.