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Claude Fable 5.1 API Cost Calculator

What Claude Fable 5.1 will cost for your workload, with its unusually cheap cache hits, the batch discount and a comparison against every other model.

Updated · By Niraj Kumar · 6 sources

Each request

Count text inCount text in
tokens

System prompt, conversation history, documents and tool definitions are all resent on every call.

tokens

The visible answer.

Count tokens from a prompt or JSON payloadShow

Plain text, OpenAI Chat or Responses JSON, or Anthropic Messages JSON. A final assistant message or a response body counts as output. Counted in your browser; nothing is uploaded.

Loading the tokenizer…

Counts use OpenAI's o200k tokenizer, so they are exact for GPT-6 and GPT-5 models, plus a few tokens of message framing. Other providers' tokenizers count the same text differently and do not publish a conversion factor; Anthropic says Claude models from 4.7 on produce about 30% more tokens than earlier Claude models. For an exact count on another model, paste one of its API responses: the usage it reports is shown above.

tokens

Thinking tokens are billed as output. Leave at 0 for models or settings that do not reason.

Volume

PricePrice

30,000 requests over 30 days.

Discounts

%
0%100%

The share of input that repeats exactly at the start of every request, such as a fixed system prompt. The prompt caching calculator prices cache writes and expiry in detail.

Batch APIBatch API
Monthly cost$1,650$0.055 a request on Claude Fable 5.1
Per 1,000 requests
$55.00
Input
$900.00
Output
$750.00
Price rank
23rd cheapest of 24
Cheapest listed model
Claude Haiku 5.5
$16.50 a month, $1,634 less
Output45%
  • Input55%
  • Output45%
Every model on this workload, per month3,000 tokens in, 500 out, 1,000 a day. Hover or focus a row for rates.
  1. 1Claude Haiku 5.5Anthropic$16.50
  2. 2GPT-6 LunaOpenAI$16.50
  3. 3Qwen3.8 FlashAlibaba$20.55
  4. 4GPT-5.6 LunaOpenAI$36.00
  5. 5DeepSeek V4.1 FlashDeepSeek$45.00
  6. 6Qwen3.7 PlusAlibaba$60.00
  7. 7Gemini 3.5 Flash-LiteGoogle$64.50
  8. 8Gemini 3.8 FlashGoogle$123.75
  9. 9Grok 4.3xAI$150.00
  10. 10Claude Haiku 4.5Anthropic$165.00
  11. 11DeepSeek V4 ProDeepSeek$178.20
  12. 12Grok 4.7xAI$270.00
  13. 13Qwen3.8 MaxAlibaba$270.00
  14. 14Claude Sonnet 5.5Anthropic$330.00
  15. 15Claude Sonnet 5Anthropic$330.00
  16. 16GPT-6.1 SolOpenAI$330.00
  17. 17GPT-6 SolOpenAI$330.00
  18. 18GPT-5.6 TerraOpenAI$360.00
  19. 19Gemini 3.1 ProGoogle$360.00
  20. 20Claude Opus 5.5Anthropic$660.00
  21. 21GPT-5.6 SolOpenAI$660.00
  22. 22Claude Opus 5Anthropic$825.00
  23. 23Claude Fable 5.1Anthropic$1,650
  24. 24GPT-6 AstraOpenAI$1,650

How the Claude Fable 5.1 API Cost Calculator works

As of October 13, 2026, Claude Fable 5.1 costs $10 per million input tokens and $50 per million output tokens, with cache hits at $0.25. A request costs its input tokens × the input rate ÷ 1,000,000 plus its output tokens × the output rate ÷ 1,000,000; multiply by requests for the monthly bill.

cost = (fresh input × input rate + cached input × cache rate + (output + reasoning) × output rate) ÷ 1,000,000

This page uses the same method as the LLM API Cost Calculator, which explains each term and assumption in full.

Worked example

A chat feature on Claude Fable 5.1 sending 3,000 input tokens and getting 500 back, 1,000 times a day.

  1. 1Input: 3,000 × $10 ÷ 1,000,000 = $0.03
  2. 2Output: 500 × $50 ÷ 1,000,000 = $0.025
  3. 3Per request: $0.055
  4. 4Per month: $0.055 × 1,000 × 30 = $1,650

$1,650 a month. Caching a fixed system prompt that makes up 80% of the input would bring it to about $948.00, and the batch API would halve either figure.

Frequently asked questions

How much does Claude Fable 5.1 cost per million tokens?

$10 per million input tokens and $50 per million output tokens at Anthropic's standard rate. Cache hits are $0.25, and writing to the cache costs $12.50 for five minutes or $20 for an hour. The batch API takes 50% off. One rate covers its full 1 million-token context window.

Why are cache hits so cheap on Claude Fable 5.1?

Anthropic prices Fable 5.1 cache hits at 0.025× the input rate, $0.25 per million tokens against $10 for fresh input, where most models charge 0.1×. A cached token on Fable 5.1 therefore costs about the same as one on Claude Sonnet 5. Workloads that resend a large, stable prefix, such as agents working over a codebase, narrow the gap to cheaper models considerably.

How big a request can Claude Fable 5.1 take?

Up to 1 million tokens of context, input and output together, and up to 128,000 output tokens per response. That is roughly 750,000 words of English. The calculator warns when a request will not fit.

Sources

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