Claude Sonnet 5.5

By Anthropic

Released: 2026-09-28

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LLM

Agents

Coding

Reasoning

Anthropic

Paid

New

Claude Sonnet 5.5, released 28 September 2026, is the second model in Anthropic's Claude 5.5 family and the faster, lower-cost complement to Claude Opus 5.5. It keeps Sonnet 5's $2 input / $10 output per million tokens ($0.20 cache reads) while generating output over 30% faster, and scores 70.6% on Terminal-Bench 4.0, above Opus 5.5's 66.4%. It has a 1M-token context window, 128K max output, adaptive thinking, and is the first Sonnet with cyber and anti-distillation classifiers.

Visit Claude Sonnet 5.5

Read our full in-depth review: Claude Sonnet 5.5 Review: Benchmarks, Pricing & Safety

AI-Powered

Leverages advanced AI technology to deliver cutting-edge capabilities and results.

Fast & Efficient

Optimized performance ensures quick results without compromising on quality.

Purpose-Built

Specifically designed for llms tasks and workflows.

Anthropic Model Timeline

28 Sept 2026

Claude Sonnet 5.5Current

1M tokens context

22 Sept 2026Claude Opus 5.5

1M tokens context

7 Aug 2026Claude Code

30 Jun 2026Claude Sonnet 5

1M tokens context

30 Jun 2026Claude Mythos 5

2 Jun 2026Anthropic Mythos 1

1 Jun 2026Claude Fable 5

1M tokens context

28 May 2026Claude Opus 4.8

Long-context context

13 Jan 2026Claude Cowork

24 Nov 2025Anthropic: Claude Opus 4.5

200k tokens context

15 Oct 2025Anthropic: Claude Haiku 4.5

200k tokens context

1 Oct 2025Claude 4.5 Haiku

200k tokens context

29 Sept 2025Anthropic: Claude Sonnet 4.5

1,000k tokens context

5 Aug 2025Anthropic: Claude Opus 4.1

200k tokens context

22 May 2025Anthropic: Claude Opus 4

200k tokens context

22 May 2025Anthropic: Claude Sonnet 4

1,000k tokens context

24 Feb 2025Anthropic: Claude 3.7 Sonnet (thinking)

200k tokens context

24 Feb 2025Anthropic: Claude 3.7 Sonnet

200k tokens context

4 Nov 2024Anthropic: Claude 3.5 Haiku

200k tokens context

22 Oct 2024Anthropic: Claude 3.5 Sonnet

200k tokens context

13 Mar 2024Anthropic: Claude 3 Haiku

200k tokens context

Specifications

pricing$2/$10 per 1M tokens (input/output), $0.20 cache reads

context Window1M tokens

AI Evaluation

4.8

Expert Rating

Text4.8/5

Coding4.9/5

Near-Opus 5.5 quality at half the price, and it actually beats Opus 5.5 on Terminal-Bench 4.0 and AutomationBench. The new default Claude for everyday coding, agents and document work.

Pros

70.6% Terminal-Bench 4.0, above Opus 5.5
Unchanged $2/$10 pricing with 30%+ faster output
1M context and 128K output

Cons

Trails Opus 5.5 on SWE-Bench Pro (81.3% vs 89.9%)
Very high token use at max effort per Artificial Analysis
Breaking API changes when migrating from Sonnet 5

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