The newest Claude Fable model is Claude Fable 5.1, released on September 1, 2026. It has been 53 days since then. The line has only 1 gap between releases so far (84 days), too few to know its usual rhythm.
How long it has been since the last release against the line's usual gap and its recent ones — the rhythm, not a date.
Latest: Claude Fable 5.1 · Sep 1, 2026
Every Monday, only when something shipped: the AI models that came out, what each one changed, and which lines are due next.
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Newest first — what each version changed versus the one before, in Anthropic's own numbers.
Anthropic's top model, refreshed: big jumps on long coding and scientific-research tasks, and cached input now costs 75% less — same headline price as Fable 5.
Compared with Claude Fable 5 · the model it replaces
Finishes over half of long multi-step coding tasks
Terminal-Bench 4.0 — long agentic coding sessions in a terminal
55.8%
▲ up from 42.0% · +14 points
Doubles its score on agentic scientific research
Terminal-Bench-Science 0.1 — running real research workflows end to end
52.6%
▲ up from 24.7% · more than doubled
Same price — and cached input now costs 75% less
Price per 1M tokens — what developers pay, input / output
$10 / $50
same as Fable 5 · cache reads now $0.25
Anthropic's new top-end model scores 80.3% on SWE-bench Pro (Anthropic gives one figure for Fable 5 and Mythos 5), up from 69.2% for Opus 4.8, at twice the price.
Compared with Claude Opus 4.8 · Anthropic's previous top model
Solves 8 in 10 hard real-world coding tasks
SWE-bench Pro — fixing real bugs in real software projects (one shared figure for Fable 5 and Mythos 5)
80.3%
▲ up from 69.2% · +11 points
More than doubles its score on the hardest coding tasks
FrontierCode Diamond — Cognition's 50 hardest tasks, graded on whether a maintainer would merge the code (one shared figure for Fable 5 and Mythos 5)
29.3%
▲ up from 13.4% · more than doubled
Costs developers twice as much to run
Price per 1M tokens — what developers pay, input / output
$10 / $50
price doubled — was $5 / $25