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Claude Sonnet 4.5 vs o1

3 vs 0 benchmarks won

Anthropic
Claude Sonnet 4.5
OpenAI
o1
Overview
CompanyAnthropicOpenAI
Release dateSep 29 2025Dec 5 2024
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 gapo1 shipped 298 days before Claude Sonnet 4.5

Which is better: Claude Sonnet 4.5 or o1?

Claude Sonnet 4.5 leads o1 on 3 of the tracked benchmarks (GPQA Diamond, SWE-Bench Verified, MMMU). o1 shipped 298 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 o1 released?
o1 was released by OpenAI on Dec 5 2024.

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