Claude Fable vs Opus: Which to Use and When (2026) - Fello AI

Title: Claude Fable vs Opus: Which One to Use Now That Opus Caught Up

URL Source: https://news.google.com/rss/articles/CBMiU0FVX3lxTE1TUzR4eGJzRzZmb2VFbVRUclE3NTlhbV90cXFVYjJVQmFLeVlzRDJaOGhIRk5YbXNITGdsNTFqcFlaekQ4cmFidVRVU0ozN19KeEVZ?oc=5

Markdown Content: Claude Opus 5.5 beats Claude Fable 5.1 on every benchmark in Anthropic's own launch table and costs 60% less per token. That flips the usual answer to Claude Fable vs Opus. Until September 22, 2026, Fable was the model you reached for when the work got hard, and Opus was the cheaper one that came close. Now Opus is the default, and Fable is what you escalate to when Opus falls short.

Claude Fable 5.1 and Claude Opus 5.5 share the same context window, output limit and knowledge cutoff. They differ on price, speed and default effort. The table compares the current versions, as listed in Anthropic's model documentation and pricing page.

Claude Opus is included on every paid plan, while Claude Fable is a paid add-on on Pro and a capped share of your usage on Max. Neither model is on the Free plan. These rows come from Claude's pricing page and Anthropic's help article on Fable models.

Claude Fable 5.1 and Claude Mythos 5.1 are the same model with different safeguards. In Anthropic's words, "Fable 5.1 is generally available, while Mythos 5.1 is available only through our trusted access programs; its safeguards are specifically designed to support work in cybersecurity and the life sciences."

The independent numbers say the same thing. On the Artificial Analysis Intelligence Index, Opus 5.5 at High effort scores 53.6 for about $1.82 per task. Fable 5.1 at its Max setting scores 53.4 for about $7.63. This guide compares the two on benchmarks, price and plan access. It also shows how the gap moved since June, explains where Mythos fits, and ends with a simple rule for when Fable is still worth paying for.

> Default to Opus: Anthropic's own model guide says "Most workloads start with Claude Opus 5.5" and moves you to Fable 5.1 only when Opus at xhigh or max effort still falls short. > Price: Opus 5.5 costs $4 / $20 per million input and output tokens. Fable 5.1 costs $10 / $50. > Plans: Opus is included on Claude Pro. Fable runs on paid usage credits on Pro and is capped at 50% of weekly limits on Max. > Independent score: on Artificial Analysis Intelligence Index v4.3.2, Opus 5.5 leads Fable 5.1 at every effort level except Low, and costs less per task at every level. > Mythos: Claude Mythos 5.1 is the same model as Fable 5.1 with different safeguards, open only to organizations Anthropic verifies.

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