Claude Sonnet 4.5

Sep 2025
Retires Nov 30, 2026Move toClaude Sonnet 5.5Newer version
Claude Sonnet 4.5
Compare in
on
—per task?
$3 / $15per 1M in / outcache $0.30
46 tok/sfirst token in 1.2 s?
1Mcontext

Alternatives?

History

7 versions
00.511.52Jul 25Oct 25Release dateFrontierMath Tier 444.5
00.511.52Jul 25Oct 25Release dateFrontierMath Tier 444.5

Benchmarks

in Chat & Knowledge
GPQA Diamond72.7#170
AIME 2025lab87
HMMT 2025 chart edition unstatedlab79.2
MMLU-Pro · official boardlab87.4

FAQ

How much does Claude Sonnet 4.5 cost?›

$3 per 1M input tokens and $15 per 1M output tokens; cached input $0.30 per 1M.

Is Claude Sonnet 4.5 free to use?›

There is no free API; the cheapest paid price is $3 per 1M input tokens.

How good is Claude Sonnet 4.5, and what is it best at?›

#220 of 334 in Chat & Knowledge, #75 of 132 in Coding, #70 of 133 in Agents & Tool Use, #21 of 195 in Writing & Language, #80 of 124 in Vision & Documents.

Is Claude Sonnet 4.5 better than GLM 5?›

On FrontierMath Tier 4, Claude Sonnet 4.5 scores 2.1 vs 2.1 — about the same.

How can I use Claude Sonnet 4.5?›

Through the API of Amazon Bedrock, Anthropic, Azure, Claude Platform on AWS, Google.

What is the context window of Claude Sonnet 4.5?›

1M tokens, with up to 64K output tokens.

When was Claude Sonnet 4.5 released? Is there a newer version?›

Released 2025-09-29. It has been superseded by Claude Sonnet 5.5.

Is Claude Sonnet 4.5 open source?›

No, Claude Sonnet 4.5 is a closed model available through an API. The closest open-weights option here is Kimi K2.6.

Can Claude Sonnet 4.5 read images?›

It accepts text and images, PDF files as input.

What is Claude Sonnet 4.5?›

Claude Sonnet 4.5 is a closed language model from Anthropic, released Sep 2025.

What are the best alternatives to Claude Sonnet 4.5?›

GPT-5.4 (2026-03-05) (cheaper), Claude Opus 4.8 (better), Kimi K2.6 (open weights).