How much does the Claude Fable 5 API cost?

Claude Fable 5 costs $10 per million input tokens and $50 per million output tokens, with cached input at $1 per million. A workload of 10M input and 1.5M output tokens per month costs about $175.00.

What is the context window of Claude Fable 5?

Claude Fable 5 supports a context window of 1,000,000 tokens (1M), with up to 128K output tokens per response.

Is Claude Fable 5 open source?

No — Claude Fable 5 is a proprietary model available through Anthropic's API and partner platforms.

What are the best alternatives to Claude Fable 5?

The closest alternatives by overall capability are Qwen3-Max, GPT-5.5, Gemini 3 Pro, Gemini 2.5 Pro. See the comparison pages for detailed head-to-head breakdowns.

Claude Fable 5

Name: Claude Fable 5
Price: 10 USD
Author: Anthropic

Anthropic·Jun 2026reasoningproprietary

Claude Fable 5 opens Anthropic's Mythos class: a capability tier the company positions above Opus. It tops SWE-bench Verified — the first model past the 95% mark — and on the harder SWE-bench Pro it scores 80.3% versus 58.6% for GPT-5.5, with spatial reasoning nearly tripling Opus 4.8's result. The premium is real: at $10/$50 per million tokens it costs twice as much as Opus 4.8, with batch processing halving that for offline workloads. For the hardest agentic engineering tasks, it is currently the strongest model money can buy.

Benchmark results

SWE-bench VerifiedCoding · #1 of 33~95%

Where it shines

State of the art on agentic coding (SWE-bench Verified and Pro)
1M-token context window with 128K max output
Large jumps in spatial reasoning and long-horizon tasks
Batch API halves the premium for offline jobs

Alternatives to Claude Fable 5

Qwen3-Max

Alibaba's trillion-parameter API flagship — frontier-adjacent quality with strong agentic tool use at mid-tier prices.

GPT-5.5

OpenAI's flagship reasoning model with a 1M-token context window, built for hard coding, science and long-horizon agentic work.

Gemini 3 Pro

Google's November 2025 frontier breakout — 91.9% GPQA Diamond and 37.5% HLE made it the reasoning leader of its generation.

Gemini 2.5 Pro

Google's 2025 workhorse flagship — first mainstream thinking model with a 1M context, still widely deployed.

Frequently asked questions

How much does the Claude Fable 5 API cost?: Claude Fable 5 costs $10 per million input tokens and $50 per million output tokens, with cached input at $1 per million. A workload of 10M input and 1.5M output tokens per month costs about $175.00.
What is the context window of Claude Fable 5?: Claude Fable 5 supports a context window of 1,000,000 tokens (1M), with up to 128K output tokens per response.
Is Claude Fable 5 open source?: No — Claude Fable 5 is a proprietary model available through Anthropic's API and partner platforms.
What are the best alternatives to Claude Fable 5?: The closest alternatives by overall capability are Qwen3-Max, GPT-5.5, Gemini 3 Pro, Gemini 2.5 Pro. See the comparison pages for detailed head-to-head breakdowns.