Claude Opus 5 vs Fable 5
Same company, two models, double the price difference. Anthropic itself says Opus 5 delivers "nearly" Fable-level performance at half the rate - I check how much that "nearly" weighs.
as of: 11 November 2026 · prices refreshed daily
Rates from OpenRouter, updated daily along with AI cost calculator.
Test results
| Test | Claude Opus 5 | Claude Fable 5 | source |
|---|---|---|---|
| SWE-bench Pro | 79.2% | 80.3% | Anthropic's launch materials |
| Frontier-Bench v0.1 | 43.3% | 33.7% | Anthropic's launch materials |
| GDPval-AA v2 | 1861 | 1747 | Anthropic's launch materials |
When Claude Opus 5
Opus 5 is today's default daily choice: in most tests it sits just behind Fable, and in Frontier-Bench and GDPval actually ahead of it, at half the cost per token. According to Anthropic on CursorBench it lands within half a percent of Fable's peak score, spending half per task.
When Claude Fable 5
Fable 5 stays where the last percent of reliability counts: multi-day autonomous agent work and the toughest coding tasks, where it still holds the highest SWE-bench Pro score. If the model works unsupervised for hours, the premium is often cheaper than its mistakes.
My verdict
Start with Opus 5 and switch to Fable only for tasks where you actually see the difference. The reverse order, Fable "just in case," is burning half your budget on psychological comfort.
Frequently Asked Questions
Which is cheaper: Claude Opus 5 or Claude Fable 5?
Claude Opus 5 costs 5 / 25 $ per million tokens (input / output), while Claude Fable 5 costs 10 / 50 $. Rates come from OpenRouter and are updated daily; the real cost of a task also depends on how many reasoning tokens the model consumes.
Are these benchmarks reliable?
Every result in the table has a cited source. Some numbers come from manufacturers' materials, measured in their own environment and highlighting their strengths - I treat them as guidance, not verdict. The fairest test remains a week of work on your own tasks.
Where can I check the real cost of working with both models?
In the AI cost calculator on this site, I convert the rates of all tracked models daily into three real tasks: an article, a hundred chat queries, and an hour of agent work - in USD.
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