Last verified: September 5, 2026 (Pacific).
Direct answer (September 2026): Headline API rates did not move when Fable 5.1 shipped on September 1. Both Fable 5 and Fable 5.1 list at $10 / MTok input and $50 / MTok output. The change that matters for agent loops is cache: Fable 5.1 cache reads are $0.25 / MTok versus $1.00 / MTok on Fable 5. On claude.ai, Fable is included only on Max and premium Team/Enterprise seats, and only up to 50% of the weekly usage pool. Pro and Team Standard pay usage credits from the first Fable token.
API rates
USD per million tokens. Context window 1M. Max output 128K. No long-context surcharge on the published card.
| Item | Fable 5 | Fable 5.1 |
|---|---|---|
| API ID | claude-fable-5 |
claude-fable-5-1 |
| Input | $10 | $10 |
| Output | $50 | $50 |
| 5-min cache write | $12.50 | $12.50 |
| 1-hour cache write | $20 | $20 |
| Cache read | $1.00 | $0.25 |
| Batch in / out | $5 / $25 | $5 / $25 |
That cache-read cut is the Sep 1 price event. Stable system prompts and repo prefixes that hit cache on 5.1 cost a quarter of what they cost on 5. Headline input/output is unchanged, so a cold one-shot is the same bill.
Opus 5 remains $5 / $25. Sonnet 5 remains $2 / $10 after Anthropic cancelled the scheduled Sep 1 step to $3 / $15. Fable is still 2× Opus on list rates.
Which plan includes Fable
Rules from Anthropic Help Center, updated this week. Fable 5 and 5.1 use the same plan logic.
- Max, Team Premium, Enterprise Premium seats: included. Cap is 50% of weekly usage limits. Same weekly pool as every other model. Fable burns that pool faster. After the cap: usage credits or switch models.
- Pro and Team Standard: not included. Credits from token one. The July 2026 $100 one-time credit was for the Fable 5 plan change only. Help Center: no equivalent credit for 5.1.
- Enterprise Standard seats: only if the org turns credits on.
- API / consumption Enterprise: list rates above.
- Free: no.
Code weekly promo and Fable cap stack on the same bar. Details: Claude Code limits, September 2026.
What 5.1 changed besides cache
Fable 5.1 launched September 1, 2026 with Mythos 5.1. Same underlying model, different safeguards. Anthropic positions 5.1 for long coding and knowledge work. US-only inference is listed at 1.1× input and output. Availability: Claude API, Bedrock, Google Cloud, Microsoft Foundry, and paid claude.ai plans under the rules above.
FAQ
Did Fable get cheaper on September 1?
Not on headline tokens. Cache reads on 5.1 dropped from $1.00 to $0.25 per million. Repeated agent context is cheaper. A fresh prompt is not.
Does Pro include Fable 5.1?
No. Pro can call it with usage credits. Included Fable lives on Max and premium seats only, and only up to half the weekly limit.
Is Fable 5.1 twice Opus 5?
On list rates, yes: $10/$50 vs Opus 5 at $5/$25. Opus 5 Fast mode lists at Fable’s standard rate. Pick Fable when the job is long-horizon and you have Max/premium inclusion or a reason to pay the cache-aware API bill.
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