Claude Fable 5.1 is Anthropic's most powerful listed model and Opus 5.5 is its leading Opus, listed at Fable 5.1-level performance for less. On fresh tokens Fable costs 2.5× more; on cached input the two are almost level.
Claude Opus 5.5 is 2.5× cheaper on input and output, but cache hits are close: $0.20 vs $0.25 per 1M. That means the output rate — $20.00 vs $50.00 — is what you are really paying for with Fable.
| Claude Opus 5.5 | Claude Fable 5.1 | |
|---|---|---|
| Provider | Anthropic | Anthropic |
| Tier | Flagship | Flagship |
| Input / 1M tokens | $4.00 | $10.00 |
| Output / 1M tokens | $20.00 | $50.00 |
| Cache hit / 1M | $0.20 | $0.25 |
| Cache write / 1M | $5.00 | $12.50 |
| Context window | 1M | 1M |
| Notes | New leading Opus model (Sep 22, 2026); Fable 5.1-level performance at 20% less than Opus 5; included on Pro/Max/Team at no extra cost | Most powerful; released Sep 1, 2026, replacing Fable 5 at same per-token price (cache reads cut 75% to $0.25) |
Claude Opus 5.5 is 2.5× cheaper on input tokens ($4.00 vs $10.00 per 1M). Claude Opus 5.5 is 2.5× cheaper on output tokens ($20.00 vs $50.00 per 1M).
| Workload | Claude Opus 5.5 | Claude Fable 5.1 | Difference |
|---|---|---|---|
| Support chatbot 10,000 conversations × (2,000 input + 400 output tokens) | $160 | $400 | Claude Opus 5.5 saves $240 |
| Document Q&A 1,000 questions × (30,000 input + 800 output tokens) | $136 | $340 | Claude Opus 5.5 saves $204 |
| Coding agent session 4M input tokens (90% cache hits) + 150,000 output tokens | $5.32 | $12.40 | Claude Opus 5.5 saves $7.08 |
Standard rates per 1M tokens from data on this site. The coding-agent row assumes 90% of input is read from the prompt cache (full input price where a model has no cache rate). Cache-write fees, batch discounts and long-context surcharges listed in the notes are not included. Updated November 2, 2026.
you want flagship-level results at the lower price — it is listed at Fable 5.1-level performance and costs 2.5× less on every fresh token.
you have measured a quality gain on your own hardest tasks that is worth 2.5× the output price, or your workload is dominated by cache reads where Fable's premium shrinks.
Anthropic prices Fable 5.1 cache hits at 2.5% of base input and Opus 5.5 at 5%, so despite Fable's higher base rate, the cache-hit prices are $0.25 and $0.20. An agent that resends a 500K-token context on every turn pays nearly the same for that context on either model. Cache writes are still 2.5× apart ($12.50 vs $5.00), and output stays 2.5× apart.
Since both share the API, a 1M-token context and standard-rate long-context pricing, a practical setup is Opus 5.5 by default with Fable 5.1 reserved for tasks that fail on Opus — for example, a final review pass. Keep the escalation rate low: at 2.5× output, sending 20% of output tokens to Fable raises the blended output rate by about 30%.
Fable 5.1 replaced Fable 5 on Sep 1, 2026 at the same per-token price, with cache reads cut 75%. Opus 5.5 followed on Sep 22, 2026. Both get Anthropic's 50% Batch API discount.
2.5× on input and output: $10.00/$50.00 versus $4.00/$20.00 per 1M tokens. Cache hits are much closer: $0.25 vs $0.20.
Opus 5.5 is listed at Fable 5.1-level performance. Test both on your own tasks — the right answer depends on your workload.
Yes. Anthropic bills the full 1M context at standard rates on both models.
How we choose: prices come from each vendor's official pricing page and are re-checked every week. We take no affiliate fees, so rankings aren't for sale.