Claude Fable 5.1 vs Claude Opus 5.5: Specs & Benchmark Comparison
Claude Fable 5.1 and Claude Opus 5.5 both come from Anthropic, and both were released in September 2026.
The two models share 4 published benchmarks. Claude Opus 5.5 leads on 4 of them. The widest gaps are on Terminal-Bench 4.0, where Claude Opus 5.5 scores 66.4% against 55.8%; AutomationBench, where Claude Opus 5.5 scores 40.0% against 31.4%. Averaged across everything we track, Claude Fable 5.1 sits at 59.7% and Claude Opus 5.5 at 71.1%.
Claude Opus 5.5 is the cheaper API at $4 per million input tokens and $20 per million output tokens, roughly 3 times cheaper than Claude Fable 5.1 at $10 and $50. Both accept a context window of about 1M tokens. Both accept text and images as input.
| Characteristic | Claude Fable 5.1 | Claude Opus 5.5 |
|---|---|---|
| Company | Anthropic | Anthropic |
| Release Date | September 1, 2026 | September 22, 2026 |
| Parameters | — | — |
| Multimodal | Yes | Yes |
| Context (input) | 1.0M | 1.0M |
| Context (output) | 128K | 128K |
| Input Price / 1M | $10.00 | $4.00 |
| Output Price / 1M | $50.00 | $20.00 |
| Average Score | 59.7% | 71.1% |
| Benchmarks | ||
| Terminal-Bench 4.0 | 55.8% | 66.4% |
| AutomationBench | 31.4% | 40.0% |
| Terminal-Bench-Science 0.1 | 52.6% | 58.7% |
| OSWorld 2.0 | 77.9% | 81.8% |
Visual Benchmark Comparison
Verdict
Claude Opus 5.5 leads in 2 out of 4 comparison categories.
Both models show comparable average scores: Claude Fable 5.1 — 0.6, Claude Opus 5.5 — 0.7.
Claude Opus 5.5 is 2.5x cheaper: input $4.00/1M vs $10.00/1M tokens.
Same context size: 1M tokens.
Claude Opus 5.5 is newer: released 9/22/2026 vs 9/1/2026.
More About These Models
Related Comparisons
Frequently Asked Questions
Which is better for coding — Claude Fable 5.1 or Claude Opus 5.5?
Which model is cheaper — Claude Fable 5.1 or Claude Opus 5.5?
Which has a larger context window — Claude Fable 5.1 or Claude Opus 5.5?
The Claude Fable 5.1 and Claude Opus 5.5 comparison is updated for 2026. Data includes benchmark results, API pricing, context window size and other specifications. For more detailed information, visit the Claude Fable 5.1 or Claude Opus 5.5 page. See also the complete list of AI model comparisons.