How much more does Claude Fable 5.1 cost than Opus 5.5?
2.5x on both sides: $10 / $50 per 1M input/output tokens against $4 / $20. Cache reads are $0.25 against $0.20.
Model vs model
Claude Fable 5.1 vs Claude Opus 5.5
Claude Fable 5.1 costs $10/$50 and Claude Opus 5.5 costs $4/$20 per 1M input/output tokens on the API.
· today
Quick answer
Use Claude Opus 5.5 by default: it is Claude Code's default model and costs $4 / $20 per 1M tokens, while Claude Fable 5.1 costs $10 / $50. Reach for Fable 5.1 when a long-running agentic coding, research or knowledge-work job justifies 2.5x the price, and note that on the Claude apps it needs usage credits on Pro or eats into a capped share of Max and Team premium limits.
Claude Fable 5.1 vs Claude Opus 5.5 specs
| Spec | Claude Fable 5.1 | Claude Opus 5.5 |
|---|---|---|
| Released | Sep 1, 2026 | Sep 22, 2026 |
| Status | Available | Available |
| API model ID | claude-fable-5-1 | claude-opus-5-5 |
| API price (in / out) | $10 / $50 per 1M tokens | $4 / $20 per 1M tokens |
| Cache read | $0.25 per 1M tokens | $0.20 per 1M tokens |
| Context window | 1M tokens | 1M tokens |
| Plans | Pro (usage credits), Max, Team premium, Enterprise | Pro, Max, Team, Enterprise |
| Platforms | Claude API, Amazon Bedrock, Claude Platform on AWS, Google Cloud, Microsoft Foundry | Claude API, Amazon Bedrock, Claude Platform on AWS, Google Cloud, Microsoft Foundry |
| Runs in | Claude, Claude Code | Claude, Claude Code |
"-" means we could not verify the value on a vendor page, not that it doesn't exist.
Claude Fable 5.1 vs Claude Opus 5.5 FAQ
Which one does Claude Code use by default?
Opus 5.5. Claude Code's docs say neither Fable model is the default on any plan or provider; you select Fable 5.1 with the `fable` alias.
Can I use Fable 5.1 on the Claude Pro plan?
Only through usage credits. Max and Team premium seats can spend up to 50% of their weekly limits on Fable; Opus is included from Pro up.
Do they have the same context window?
Yes. Both have a 1M-token context window by default and 128k max output tokens.
Also compared
Sources
- Claude Developer Platform release notesread 2026-09-24
- Claude API pricingread 2026-09-24
- Claude models overviewread 2026-09-24
- Claude Code model configurationread 2026-09-24
- Claude plans and pricingread 2026-09-24
- Anthropic: Claude Opus 5.5 launchread 2026-09-24