Anthropic · Claude Sonnet line · lightweight
Claude Sonnet 5.5 was released by Anthropic on September 28, 2026, as a lightweight model in the Claude Sonnet line.
Scores 18 points higher than Sonnet 5 on the all-round intelligence index and runs over 30% faster, at the same $2 / $10 price per 1M tokens.
Compared with Claude Sonnet 5 · the model it replaces
Makes the right code edits more than half the time inside an editor
CursorBench 4.0 — editing code the way developers do in an IDE
55.5%
▲ up from 34.1% · +21.4 points
Scores 18 points higher on the all-round intelligence index
Artificial Analysis Intelligence Index v4.3.2 — one score averaging 10 hard tests
56
▲ max effort · up from 38 · +18 points
Costs the same as the model it replaces
Price per 1M tokens — what developers pay, input / output
$2 / $10
same as Claude Sonnet 5
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Claude Sonnet 5.5 is the current model in this line. The card shows how long it has been since the last release against the line's usual gap and its recent ones — the rhythm, not a date.
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