SIDE BY SIDE
Claude Fable 5.1 vs Claude Opus 5.5
Both are Claude models. Claude Opus 5.5 was added to OpenRouter on 2026-09-22, Claude Fable 5.1 on 2026-09-01.
| Field | Claude Fable 5.1 | Claude Opus 5.5 |
|---|---|---|
| Provider | Anthropic | Anthropic |
| Family | Claude | Claude |
| Province | The High Peaks | The High Peaks |
| Context window | 1M tokens | 1M tokens |
| Maximum output | 128K tokens | 128K tokens |
| Input / 1M tokens | $10.0 | $4.00 |
| Output / 1M tokens | $50.0 | $20.0 |
| Accepts | text, files, images | text, files, images |
| Produces | text | text |
| Reasoning | Yes | Yes |
| Tool use | Yes | Yes |
| Added to OpenRouter | 2026-09-01 | 2026-09-22 |
| Model ID | anthropic/claude-fable-5.1 | anthropic/claude-opus-5.5 |
Questions and answers
Which is cheaper, Claude Fable 5.1 or Claude Opus 5.5?
Claude Opus 5.5 costs less for both input ($4.00 vs $10.0) and output ($20.0 vs $50.0) per million tokens. On input, Claude Opus 5.5 is 60% cheaper.
Which has the larger context window?
Both have a 1M-token context window.
What can one do that the other cannot?
Nothing among reasoning, tool use and image input: both support reasoning, tool use and image input.
Answers are computed from the 2026-10-24 catalog snapshot.