Anthropic: Claude Fable 5.1
Claude Fable 5.1 is a reasoning model from Anthropic released on Aug 29, 2026. It reads text, images and files and writes text, with a 1M token context window and up to 128K tokens per reply.
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It costs $10 per million input tokens and $50 per million output tokens. Cached input bills at $0.25, 98% less than fresh input.
It supports tool calling, structured JSON output and prompt caching.
29 providers serve it, including Amazon Bedrock, Azure and Vercel AI Gateway.
On the Artificial Analysis Intelligence Index it scores 53.4, which places it in the top three, at number 3, among the 43 models I track with independent scores.
- Modalities
- In / out price
- $10 / $50 per 1M
- Context
- 1M
- Max output
- 128K
- Released
- Aug 29, 2026
- Knowledge cutoff
- Jun 2026
- Tool calling
- Structured output
- Reasoning
- Prompt caching
- Open weights
- Free to use
Claude Fable 5.1 pricing
USD, as listed on Oct 15, 2026. Most bills are input heavy, so the cached input rate matters as much as the headline price.
| Input | $10 / 1M tokens | |
|---|---|---|
| Output | $50 / 1M tokens | |
| Cached input (read) | $0.25 / 1M tokens | 98% off input |
| Cache write | $12.50 / 1M tokens |
Claude Fable 5.1 providers
29 providers serve it, including Amazon Bedrock, Azure and Vercel AI Gateway. Each host sets its own price and limits, so the cheapest one is not always the one with the longest context.
| Provider | Input /M | Output /M | Cache read /M | Context | Max output |
|---|---|---|---|---|---|
| Anthropic First party | $10 | $50 | $0.25 | 1M | 128K |
| Amazon Bedrock | $10 | $50 | $0.25 | 1M | 128K |
| Azure | $10 | $50 | $0.25 | 1M | 128K |
| Vercel AI Gateway | $10 | $50 | $0.25 | 1M | 128K |
| Vertex | $10 | $50 | $0.25 | 1M | 128K |
| Vertex (Anthropic) | $10 | $50 | $0.25 | 1M | 128K |
| 302.AI | $10 | $50 | – | 1M | 128K |
| Azure Cognitive Services | $10 | $50 | $0.25 | 1M | 128K |
| Cloudflare AI Gateway | $10 | $50 | $0.25 | 1M | 128K |
| CrossModel | $10 | $50 | $0.25 | 1M | 128K |
| DevPass (LLM Gateway) | $10 | $50 | $0.25 | 1M | 128K |
| DigitalOcean | $10 | $50 | $0.25 | 1M | 128K |
Showing 12 of 29 providers: the lab first, then the major clouds, then the cheapest resellers.
What Claude Fable 5.1 costs per month
Pick a workload close to yours or type your own volumes.
Independent benchmarks
Measured by third parties, not reported by Anthropic. Each links to its source and shows the date I checked it.
A composite of 10 independent evaluations (agents 30%, coding 20%, scientific reasoning 20%, general 30%), run by Artificial Analysis on each model, version 4.3.2.
Artificial Analysis, checked Oct 10, 2026
Human preference: people compare two anonymous answers and pick the better one. Ratings from the Text Arena overall board, style control on.
Arena (formerly LMArena), checked Oct 10, 2026
Agentic coding in a real terminal: can the model, driving an agent harness, finish multi step software and ops tasks. Resolution rate.
Terminal-Bench, checked Oct 10, 2026
Abstract reasoning on visual puzzles the model has not seen, semi private set. Hard to memorise, so it tracks reasoning more than knowledge.
ARC Prize, checked Oct 10, 2026
Expert level questions across many fields, no tools allowed. The Diamond set is 1,000 questions. Few models are on it yet.
Scale Labs, checked Oct 10, 2026
Median output tokens per second measured by Artificial Analysis on the provider API, for the same model setting as its index score.
Artificial Analysis, checked Oct 10, 2026
Benchmarks Anthropic reports (14)
- terminal-bench-science-0-1 (Terminal-Bench-Science 0.1 (standard error ±3.5–4.5 pts))52.6%
- terminal-bench-4 (Terminal-Bench 4.0)55.8%
- gdpval-aa-v2 (GDPval-AA v2)1853
- osworld-2-0 (OSWorld 2.0, partial credit, benchmark authors' August 2026 task release)77.9%
- osworld-2-0 (OSWorld 2.0, strict, August 2026 task release)41.7%
- hle-no-tools (Humanity's Last Exam, no tools)60.9%
- hle-with-tools (Humanity's Last Exam, with tools)65%
- automationbench (Zapier AutomationBench)31.4%
- cursorbench-3-2 (CursorBench 3.2.0)73.4%
- frontiercode-1-1-main (FrontierCode v1.1 (Main), max effort)50.3%
- cursorbench-4 (CursorBench 4.0, max effort)51.8%
- gdpval-aa-v2-1 (GDPval-AA v2.1 (Artificial Analysis), max effort)1735
- osworld-2-1 (OSWorld 2.1, partial credit)80.7%
- chartography (Chartography, with tools)88.4%
Labs pick their own settings and harnesses, so compare these only within one lab.
Supported request parameters
What you can set when you call Claude Fable 5.1 through an OpenAI compatible API.
- Tools
tools - Structured outputs
structured_outputs - Reasoning
reasoning
Alternatives to Claude Fable 5.1
Models that take the same inputs and call tools, closest in price, cheaper ones first.
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Claude Fable 5.1 questions
How much does the Claude Fable 5.1 API cost?
$10 per million input tokens and $50 per million output tokens, with cached input at $0.25. The estimator on this page turns that into a monthly bill for your own workload.
What is the context window of Claude Fable 5.1?
1,000,000 tokens of input, and it can write up to 128,000 tokens in one reply. As a rough guide, a million tokens is around 750,000 English words.
Which providers serve Claude Fable 5.1?
29 providers serve it, including Amazon Bedrock, Azure and Vercel AI Gateway. Prices differ by host, so the Providers table on this page lists each one with its input and output price.
Does Claude Fable 5.1 support tool calling?
Yes. It accepts tool definitions and can return JSON that matches a schema, which is what an agent needs to call your APIs.
Is Claude Fable 5.1 open source?
No. Anthropic serves it through an API only, so you cannot download the weights or host it yourself.
When was Claude Fable 5.1 released?
Aug 29, 2026, with training data up to Jun 2026.
How good is Claude Fable 5.1 compared with other models?
It scores 53.4 on the Artificial Analysis Intelligence Index and 1501 on the Arena text leaderboard. Benchmarks are a shortlist, not a verdict: test the top two or three candidates on your own tasks before you commit.
Catalog data from models.dev (MIT licensed), refreshed daily, last on Oct 15, 2026. Independent scores from my hand checked rankings, sources linked above. The summary is written from these facts.
Building on Claude Fable 5.1?
I test your real tasks on it and the two closest alternatives, then ship the agent on whichever wins on cost and accuracy.
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