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Models / Anthropic

Claude Sonnet 5.5

GA

The current Sonnet: 'The best combination of speed and intelligence'. Released September 28, 2026 ('Latest. Released September 28, 2026' on its model page); the deprecations table reads Active with a tentative retirement not sooner than September 28, 2027. Anthropic's recommended replacement for claude-sonnet-4-5-20250929, deprecated September 30, 2026 and retiring November 30, 2026. $2 in / $10 out per MTok; 5m cache write $2.50/MTok, 1h cache write $4/MTok; cache hits $0.20/MTok. Batch $1 in / $5 out. Adaptive thinking (not always-on); effort defaults to high. 1M context, 128K max output (300K via the Batch API output-300k-2026-03-24 beta header). Reliable knowledge cutoff Jun 2026; training data cutoff Jun 2026. Tool-use system prompt overhead 286 tokens. Supersedes Claude Sonnet 5, now a legacy model. Added 2026-10-02, four days after release: the delay is ours.

Claude Sonnet 5.5 by Anthropic costs $2 per 1M input tokens and $10 per 1M output tokens ($4/1M blended), with a 1M (1.000.000-token) context window. It is generally available (GA), with a knowledge cutoff of Jun 2026.

Last verified: 15 Oct 2026 · sourced from official provider documentation

Provider
Anthropic
Status
GA
Input price
$2 / 1M tokens
Output price
$10 / 1M tokens
Cached input
$0.2 / 1M tokens
Blended price
$4 / 1M tokens
Context window
1.000.000 tokens (1M)
Max output
128.000 tokens
Modality
text, image, vision
Open weights
No — API only
Knowledge cutoff
2026-06
Released
28 Sep 2026
API string
claude-sonnet-5-5

Source: Anthropic official documentation ↗

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FAQ

Claude Sonnet 5.5 — questions & answers

How much does Claude Sonnet 5.5 cost?

Claude Sonnet 5.5 is priced at $2 per 1M input tokens and $10 per 1M output tokens ($4/1M blended at a 3:1 input-to-output ratio), with cached input at $0.2 per 1M tokens.

What is the context window of Claude Sonnet 5.5?

Claude Sonnet 5.5 has a 1.000.000-token context window (1M), with up to 128.000 output tokens per request.

Is Claude Sonnet 5.5 deprecated?

No — Claude Sonnet 5.5 is generally available (GA) and not currently scheduled for deprecation or retirement in our tracker.

Does Claude Sonnet 5.5 support image or vision input?

Yes — Claude Sonnet 5.5 accepts image input. Listed modalities: text, image, vision.

Can I self-host Claude Sonnet 5.5?

No — Claude Sonnet 5.5 is proprietary. Its weights are not publicly released, so it is available only through Anthropic's API (or hosted partners), not for self-hosting.

What is the API model string for Claude Sonnet 5.5?

The API model identifier for Claude Sonnet 5.5 is "claude-sonnet-5-5" when calling Anthropic's API.

What is Claude Sonnet 5.5's knowledge cutoff?

Claude Sonnet 5.5's training knowledge cutoff is Jun 2026.