Claude Fable 5.1 vs Claude Opus 5.5: pricing compared
For a 30-step coding agent run, Claude Opus 5.5 is 2.2x cheaper ($1.66 vs $3.63). Prices verified 2026-10-18.
| Claude Fable 5.1 | Claude Opus 5.5 | |
|---|---|---|
| Provider | Anthropic | Anthropic |
| Input / 1M | $10.00 | $4.00 |
| Cached input / 1M | $0.25 | $0.20 |
| Output / 1M | $50.00 | $20.00 |
| Batch discount | 50% | 50% |
| Context window | 1M | 1M |
| Long-context tier | none | none |
Cost on real workloads
| Workload | Claude Fable 5.1 | Claude Opus 5.5 |
|---|---|---|
| 10,000 chatbot replies 2,000 input + 400 output tokens each, 50% of the prompt cached | $303 | $122 |
| One 30-step coding agent run 12K system + tools prompt, 1K output and 3K tool result per step, caching on | $3.63 | $1.66 |
| 1M documents classified (batch) 600 input + 20 output tokens each, batch API where available | $3,500 | $1,400 |
Price is only half the decision: a cheaper model that needs more steps or retries can cost more per finished task. Run your own numbers in the calculator (both models pinned), or see how both rank in the use-case guides.
FAQ
Is Claude Fable 5.1 cheaper than Claude Opus 5.5?
For a typical 30-step coding agent run with caching, Claude Opus 5.5 costs $1.66 and Claude Fable 5.1 costs $3.63, so Claude Opus 5.5 is 2.2x cheaper. Per 1M tokens, Claude Fable 5.1 is $10.00 / $50.00 and Claude Opus 5.5 is $4.00 / $20.00.
Which has the bigger context window?
Claude Fable 5.1: 1,000,000 tokens. Claude Opus 5.5: 1,000,000 tokens.