Anthropic's new flagship reasoning model tops the Artificial Analysis Intelligence Index but burns through 87 million output tokens in the process
Running a benchmark suite on Anthropic’s newest AI model now costs roughly what a used Honda Civic does. Claude Fable 5, the company’s latest flagship reasoning model, racked up a bill of $6,227.74 just to complete the Artificial Analysis Intelligence Index evaluations.
The model launched on June 9, 2026, and immediately claimed the top spot on the Intelligence Index with a score of 64.9. That dethroned its predecessor, Claude Opus 4.8, and left OpenAI’s GPT-5.5 in the rearview at 58.6.
The price of being the best #
Claude Fable 5 is priced at $10 per million input tokens and $50 per million output tokens. The benchmark evaluation consumed 87 million output tokens, which is why the final tab landed north of $6K.
Reasoning models produce far more output tokens than standard chat models because they work through problems step by step. That 87 million token output figure is a direct consequence of asking a reasoning model to grind through coding challenges, logic puzzles, and complex multi-step evaluations.
Anthropic does offer a 90% discount on prompt caching for repeated input hits, but that doesn’t help much when your primary cost driver is output generation.
What you get for the money #
On SWE-Bench Pro, a benchmark that tests a model’s ability to solve real-world software engineering problems, Fable 5 scored 80.3% accuracy. That’s a substantial improvement over Claude Opus 4.8’s 69.2% and ahead of GPT-5.5’s 58.6%.
The model also ships with a 1 million token context window and handles both image and text inputs.
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