Claude Fable 5.1 improves on Claude Fable 5 across the board, with the biggest gains in agentic coding, long-running agentic workflows, and knowledge work: long code refactors, front-end and visual...
Model details →Anthropic: Claude Fable 5.1 vs Claude Opus 5 (Fast)
Anthropic: Claude Fable 5.1 and Claude Opus 5 (Fast) are evenly matched on 6 axes — pick the one whose provider, latency, or licensing fits your stack.
Fast-mode variant of [Opus 5](/anthropic/claude-opus-5) - identical capabilities with higher output speed at 2x pricing relative to regular Opus 5. Learn more in Anthropic's docs: https://platform.claude.com/docs/en/build-with-claude/fast-…
Model details →Side-by-side comparison
| Capability | Anthropic: Claude Fable 5.1 | Claude Opus 5 (Fast) | Winner |
|---|---|---|---|
| Context window Maximum number of input tokens the model can attend to in a single request. | 1M | 1M | Tie |
| Input price (per 1M) Cost per million input tokens billed by the provider. | $10.00 | $10.00 | Tie |
| Output price (per 1M) Cost per million output tokens billed by the provider. | $50.00 | $50.00 | Tie |
| Tool / function calling First-class support for emitting structured tool calls. | Yes | Yes | Tie |
| Vision input Accepts image inputs alongside text. | Yes | Yes | Tie |
| Reasoning mode Internal chain-of-thought / extended-thinking support. | Yes | Yes | Tie |
Frequently asked questions
Is Anthropic: Claude Fable 5.1 better than Claude Opus 5 (Fast)?
Anthropic: Claude Fable 5.1 and Claude Opus 5 (Fast) are evenly matched on 6 axes — pick the one whose provider, latency, or licensing fits your stack.
What's the price difference between Anthropic: Claude Fable 5.1 and Claude Opus 5 (Fast)?
Input: $10.00 vs $10.00 per 1M tokens. Output: $50.00 vs $50.00 per 1M tokens.
What context windows do Anthropic: Claude Fable 5.1 and Claude Opus 5 (Fast) support?
Anthropic: Claude Fable 5.1 supports up to 1M tokens. Claude Opus 5 (Fast) supports up to 1M tokens.
Do both Anthropic: Claude Fable 5.1 and Claude Opus 5 (Fast) support tool calling?
Anthropic: Claude Fable 5.1: yes. Claude Opus 5 (Fast): yes.