Anthropic: Claude Fable 5.1

anthropic/claude-fable-5.1

Claude Fable 5.1 improves on Claude Fable 5 across the board, with the biggest gains in agentic coding, long-running agentic workflows, and knowledge work: long code refactors, front-end and visual...

Modalities

In / out price

$10 / $50 per 1M

Context

Released

Sep 1, 2026

Why use Claude Fable 5.1

Understands images
Reads PDFs and other files
Step-by-step reasoning mode
Tool and function calling (agent-ready)
Structured (JSON) outputs
Very long context: whole books or codebases in one prompt

Pricing

Input	$10 / 1M tokens
Output	$50 / 1M tokens
Cached input (read)	$0.25 / 1M tokens
Cache write	$12.5 / 1M tokens

List prices via OpenRouter, checked daily. Real cost depends on the provider and on reasoning tokens.

How it ranks

Intelligence index53.4

Coding index81.6

Agentic index57.9

Source: Artificial Analysis (artificialanalysis.ai) via OpenRouter (openrouter.ai/rankings).

Cost calculator

Pick a task, set how often you run it, and compare what it costs on each model.

TaskInput tokens≈ 602 wordsOutput tokens≈ 1,504 wordsRuns per month

Input served from cache: 0%Repeated prompts (same instructions or document) are billed at the cheaper cache-read price where the model supports it.

Model	Per run	Per month	Per 1,000 runs
Anthropic: Claude Fable 5.1	$0.108	$108	$108

Estimates from list prices via OpenRouter; real bills vary by provider and reasoning tokens.

Will it fit? Context window simulator

Each square is about one page (500 words). Colored squares are your content; grey squares are free space in the model's context window.

Your content

Novel (90,000 words)

Total: about 120,000 tokens (≈ 90,226 words). Token counts are estimates.

Models

Zoom (square size): 6pxZoom out to see a whole million-token window at once.