Model comparison

Claude Fable 5.1 vs Claude Opus 5.5: pricing, context and features compared

Claude Fable 5.1 costs $10 per million input tokens and $50 per million output tokens; Claude Opus 5.5 costs $4 and $20. Here is how they compare on specs, on what real workloads cost, and on which to pick for what, from prices updated daily.

Fable sits above Opus in Anthropic’s line-up and costs more per token. Teams compare the two to decide which work is worth sending to the top tier and which Opus can handle.

Claude Fable 5.1Anthropic

Input / 1M: $10
Output / 1M: $50
Context: 1,000,000
Max output: 128,000

Full Claude Fable 5.1 pricing and specs

Claude Opus 5.5Anthropic

Input / 1M: $4
Output / 1M: $20
Context: 1,000,000
Max output: 128,000

Full Claude Opus 5.5 pricing and specs

Verdict

Claude Fable 5.1 or Claude Opus 5.5: which to pick

Claude Opus 5.5 has the lower list prices: 2.5× cheaper per input token and 2.5× per output token. On our data, Claude Opus 5.5 has the edge for the lowest bill, very long prompts, repeated prompts and batch jobs, and Claude Fable 5.1 has no measurable edge; its case rests on answer quality, so choose it only if it does clearly better in your own tests. For scale, a support chatbot handling 1,000 requests a day costs about $842.16 a month on Claude Fable 5.1 and $339.15 on Claude Opus 5.5.

Lowest bill for typical workloadsPick Claude Opus 5.5: Claude Opus 5.5 costs less on all 4 workloads below, 2.4× to 2.5× cheaper than Claude Fable 5.1 at list prices.
Very long prompts (whole codebases, long documents)Pick Claude Opus 5.5: Both read about 1,000,000 tokens per request. One 800,000-token prompt with a 2,000-token reply costs $8.10 on Claude Fable 5.1 and $3.24 on Claude Opus 5.5. Neither has a long-prompt surcharge in our data.
Long replies (reports, large code files)Either: Both cap a single reply at about 128,000 tokens.
Images, audio, video or files in the promptEither: Both accept images and files as well as text.
Repeated long prompts (prompt caching)Pick Claude Opus 5.5: Claude Opus 5.5 bills cached input at $0.20 per 1M (5% of its input price), against $0.25 per 1M (3% of its input price) for Claude Fable 5.1.
Overnight batch jobsPick Claude Opus 5.5: Both offer batch prices; on the document summariser workload Claude Opus 5.5 costs $200.75 a month against $501.88.
Self-hosting or choosing your own hostEither: Neither has downloadable weights: both are only available through their provider’s API and cloud partners.

Criteria use only list prices, published limits and the features each provider declares. We don’t rank answer quality; test both models on your own prompts before you commit.

Specs

Claude Fable 5.1 vs Claude Opus 5.5 side by side

Specs of Claude Fable 5.1 and Claude Opus 5.5; the better value on each row is marked
Spec	Claude Fable 5.1	Claude Opus 5.5
Provider	Anthropic	Anthropic
Input / 1M tokens	$10	$4 (better)
Output / 1M tokens	$50	$20 (better)
Cached input / 1M	$0.25	$0.20 (better)
Cache write / 1M	$12.50	$5
Batch in / out	$5 / $25	$2 / $10 (better)
Long-prompt price	None	None
Context window	1,000,000	1,000,000
Max output	128,000	128,000
Accepts	text, images, files	text, images, files
Image input	Yes	Yes
Tool calling	Yes	Yes
Reasoning mode	Yes	Yes
Prompt caching	Yes	Yes
Structured output	Yes	Yes
Open weights	No	No
Knowledge cutoff	Not published	Not published
First listed	2026-09-01	2026-09-22

Prices in US dollars per million tokens. Highlighted: the lower price or larger limit where the difference is over 5%. Features are as declared by each provider’s API; “First listed” is when our data source first listed the model. Long-prompt prices apply to the whole request once the prompt passes the threshold.

Costs

What Claude Fable 5.1 and Claude Opus 5.5 cost for real workloads

Workload	Tokens in / out	Requests/day	Claude Fable 5.1 / month	Claude Opus 5.5 / month	Cheaper
Support chatbotCalculator: Claude Fable 5.1 · Claude Opus 5.5	1,500 / 400	1,000	$842.1650% cached	$339.1550% cached	Claude Opus 5.5 (2.5×)
RAG appCalculator: Claude Fable 5.1 · Claude Opus 5.5	6,000 / 500	500	$1,11520% cached	$447.7320% cached	Claude Opus 5.5 (2.5×)
Coding agentCalculator: Claude Fable 5.1 · Claude Opus 5.5	40,000 / 2,000	200	$1,14480% cached	$476.9380% cached	Claude Opus 5.5 (2.4×)
Document summariserCalculator: Claude Fable 5.1 · Claude Opus 5.5	8,000 / 600	300	$501.88batch	$200.75batch	Claude Opus 5.5 (2.5×)

Each row uses the same token counts for both models and list prices, with caching and batch discounts only where the provider publishes them. A month is 365 ÷ 12 days. The support chatbot reads 50% of its prompt from the cache. The RAG app reads 20% of its prompt from the cache. The coding agent reads 80% of its prompt from the cache. The document summariser runs as a batch job where a batch price exists. Open either model in the LLM cost calculator to change any number.

Tokenizers

Are their per-token prices comparable?

Yes: Claude Fable 5.1 and Claude Opus 5.5 use the same tokenizer, so a given text is the same number of tokens on both and the prices above compare directly.

Model	Tokenizer	Tokens per 1,000 words	Output per 1M words
Claude Fable 5.1	Claude (Opus 4.7 and later)Provider’s published figure	1,802	$90.09
Claude Opus 5.5	Claude (Opus 4.7 and later)Provider’s published figure	1,802	$36.04

English prose, measured on the Universal Declaration of Human Rights (2026-10-11) or taken from the provider’s published words-per-token figure. Code, JSON and other languages use more tokens per word. Count your own text in the token counter or convert with tokens to words.

FAQ

Claude Fable 5.1 vs Claude Opus 5.5 questions

Is Claude Fable 5.1 cheaper than Claude Opus 5.5?

Claude Fable 5.1 costs $10 per million input tokens and $50 per million output tokens; Claude Opus 5.5 costs $4 and $20. For a support chatbot handling 1,000 requests a day, that is about $842.16 a month on Claude Fable 5.1 against $339.15 on Claude Opus 5.5, so Claude Opus 5.5 is 2.5× cheaper there. Try your own numbers in the LLM cost calculator.

Which has the bigger context window, Claude Fable 5.1 or Claude Opus 5.5?

Their context windows are about the same size. Claude Fable 5.1 reads up to 1,000,000 tokens (roughly 750,000 English words) and writes up to 128,000 tokens per reply. Claude Opus 5.5 reads up to 1,000,000 tokens (roughly 750,000 English words) and writes up to 128,000 tokens per reply. The window is shared between your prompt and the reply. Word counts use a rough 0.75 words per token; real ratios depend on the tokenizer.

Is Claude Fable 5.1 or Claude Opus 5.5 better for coding?

We don’t publish benchmark scores, so this page can’t say which writes better code. What we can show is cost: a coding agent re-sending 40,000 tokens of context (80% cached) and writing 2,000 tokens, 200 times a day, costs about $1,144 a month on Claude Fable 5.1 and $476.93 on Claude Opus 5.5. Both support tool calling. Test both on tasks from your own repository.

Can Claude Fable 5.1 and Claude Opus 5.5 read images?

Claude Fable 5.1 accepts images and files as well as text. Claude Opus 5.5 accepts images and files as well as text. So both can read screenshots, photos and scanned pages. This is what each provider declares for its API, not a measure of how well it works.

Are Claude Fable 5.1 and Claude Opus 5.5 open source?

No. Neither Claude Fable 5.1 nor Claude Opus 5.5 has published weights: you can only use them through Anthropic’s API and their cloud partners. If you need a model you can host yourself, compare open-weight options in the model comparison table.

Do Claude Fable 5.1 and Claude Opus 5.5 count tokens the same way?

Yes. Both use the same tokenizer (Claude (Opus 4.7 and later)), so the same text is the same number of tokens on each and their per-token prices compare directly: about 1,802 tokens per 1,000 English words (the provider’s published figure). Other languages and code use more tokens per word. Count your own text with the token counter or convert with tokens to words.

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