Breaking

Anthropic Makes Claude Sonnet 5.5 Available as a Faster, Lower-Cost Claude 5.5 Model

September 28, 2026 at 14:10 EDT

Foundation Models
AI Agents
Software Dev & Coding

Anthropic made Claude Sonnet 5.5 available on Monday, September 28, positioning it as a faster, lower-cost Sonnet-tier model for everyday work in the Claude 5.5 family. The release follows Claude Opus 5.5 by six days and brings the 5.5 generation from Anthropic's higher-end Opus tier into the model class many developers use for routine coding, document production and fast iteration.

Sep. 28, 2026 · Anthropic

Claude Sonnet 5.5 moves the 5.5 family into everyday work

The new Sonnet model is positioned as a faster, lower-cost complement to Opus 5.5 for bug fixes, polished documents, spreadsheets, slides and design iteration.

>30%

faster than Sonnet 5

30%

lower cost for most work, up to

$2 / $10

input and output per million tokens

Work-cost index

Anthropic's claim implies a lower cost to complete similar work, even with the same per-token rate.

100

Sonnet 5 baseline

Sonnet 5.5, best case

Where it fits

Bug fixes→Documents→Slides and sheets→Design iteration

Upside

Faster responses and fewer tokens per task could make Sonnet 5.5 the practical default for routine agent loops.

Watchpoints

Teams will test whether the cost claim holds in long runs and whether cyber safeguards avoid blocking benign work.

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