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

Rankingin non-thinking mode?

Full ranking →
1Gemini 4 Argon77.52MiniMax M3.1 Flash72.53Sonnet 5.571.84Muse Wonder Full71.35Opus 5.569.5
···
69K2 Horizon 3.7B14.770Sonnet 4.514.171MiMo v2.5 Pro13.7

Strong at

B
Tool calling#92 of 242Knowledge#90 of 318
C
Coding#75 of 132Agents & work tasks#91 of 175Reasoning#220 of 334Science#168 of 312Long context#168 of 273Instructions#142 of 245Vision#80 of 124

Alternatives?

ModelScoreCostPer taskWhat changes
CheaperMiniMax M3.1 Flashthinking×5.2-60%$0.22Complete model response must be appendedBetterGPT-5.6 Lunamedium+64%-97%$0.016OpenDeepSeek V4.1 Flash 1017max×4.7-53%$0.26Pass back reasoning_content · Chat Completions+4CheaperGPT-6.1 Solxhigh×4.7-29%$0.39Remove unsupported parameters+5CheaperMiMo v2.6 FlashthinkingOpen×4.6-89%$0.062Pass back reasoning_content+3

History

7 versions
20406080Oct 25Jan 26Apr 26Jul 26Oct 26Release dateAutomationBench-AA4.54.655.5
20406080Jan 26Jul 26Release dateAutomationBench-AA4.54.655.5

Benchmarks

in Agents & Tool Use
Terminal-Bench Hard (version unstated)28.8#61
AA-LCR (long context) 1.154#169
τ²-bench · AA70.5#94
Tau2-Benchlab84.7
MCP-Universelab46.5
MCP-Marklab33.3
Tool-Decathlonlab38.6
HLE without toolslab13.7

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 K2 Horizon 3.7B?›

On AutomationBench-AA, Claude Sonnet 4.5 scores 14.1 vs 14.7 — 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 It has been superseded by Claude Sonnet 5.5.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 DeepSeek V4.1 Flash 1017.

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?›

MiniMax M3.1 Flash (cheaper), GPT-5.6 Luna (better), DeepSeek V4.1 Flash 1017 (open weights).