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Claude Opus 4.5 vs o3

2 vs 0 benchmarks won

Anthropic
Claude Opus 4.5
OpenAI
o3
Overview
CompanyAnthropicOpenAI
Release dateNov 24 2025Apr 16 2025
Model type
Open sourceNoNo
Specifications
Parameters
Context window
Benchmarks
Science reasoning
GPQA Diamond
87%
Software engineering
SWE-Bench Verified
80.9%
Multimodal understanding
MMMU
Timeline
Release gapo3 shipped 222 days before Claude Opus 4.5

Which is better: Claude Opus 4.5 or o3?

Claude Opus 4.5 leads o3 on 2 of the tracked benchmarks (GPQA Diamond, SWE-Bench Verified, MMMU). o3 shipped 222 days before Claude Opus 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 Opus 4.5 released?
Claude Opus 4.5 was released by Anthropic on Nov 24 2025.
When was o3 released?
o3 was released by OpenAI on Apr 16 2025.

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