Claude Sonnet 4.5

by Anthropic

Claude Sonnet 4.5 is a model from Anthropic, released on September 29, 2025. It has a 200K-token context window and can generate up to 64K output tokens. API pricing is $3 per 1M input tokens and $15 per 1M output tokens.

Claude Sonnet 4.5 is the best coding model in the world. It's the strongest model for building complex agents. It’s the best model at using computers. And it shows substantial gains in reasoning and math. Highest intelligence across most tasks with exceptional agent and coding capabilities.

Key specs

ProviderAnthropic
Release date2025-09-29
Licenseproprietary
Context window200K tokens
Max output64K tokens
Input price$3 / 1M tokens
Output price$15 / 1M tokens
Intelligence Score32
Coding index20.9

Quick answers

What is the context window of Claude Sonnet 4.5?

Claude Sonnet 4.5 has a context window of 200K tokens, with a maximum output of 64K tokens per response.

How much does Claude Sonnet 4.5 cost?

Claude Sonnet 4.5 costs $3 per 1M input tokens and $15 per 1M output tokens through the API.

Is Claude Sonnet 4.5 open source?

No. Claude Sonnet 4.5 is a proprietary model from Anthropic (proprietary license).

When was Claude Sonnet 4.5 released?

Anthropic released Claude Sonnet 4.5 on September 29, 2025.

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