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Claude Sonnet 4.5 vs GPT-4.5

3 vs 0 benchmarks won

Anthropic
Claude Sonnet 4.5
OpenAI
GPT-4.5
Overview
CompanyAnthropicOpenAI
Release dateSep 29 2025Feb 27 2025
Model type
Open sourceNoNo
Specifications
Parameters
Context window
Benchmarks
Science reasoning
GPQA Diamond
83.4%
Software engineering
SWE-Bench Verified
77.2%
Multimodal understanding
MMMU
68%
Timeline
Release gapGPT-4.5 shipped 214 days before Claude Sonnet 4.5

Which is better: Claude Sonnet 4.5 or GPT-4.5?

Claude Sonnet 4.5 leads GPT-4.5 on 3 of the tracked benchmarks (GPQA Diamond, SWE-Bench Verified, MMMU). GPT-4.5 shipped 214 days before Claude Sonnet 4.5, so benchmark comparisons should account for the intervening progress.

Published specifications for these two models are limited — see each model page for the latest details.

Direct benchmark comparisons are unavailable — at least one of these models has not published scores on GPQA Diamond, SWE-Bench Verified, or MMMU.

Frequently asked questions

When was Claude Sonnet 4.5 released?
Claude Sonnet 4.5 was released by Anthropic on Sep 29 2025.
When was GPT-4.5 released?
GPT-4.5 was released by OpenAI on Feb 27 2025.

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