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Claude Sonnet 4.5 vs Gemini 3.1 Flash

3 vs 0 benchmarks won

Anthropic
Claude Sonnet 4.5
Google
Gemini 3.1 Flash
Overview
CompanyAnthropicGoogle
Release dateSep 29 2025Feb 26 2026
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 gapClaude Sonnet 4.5 shipped 150 days before Gemini 3.1 Flash

Which is better: Claude Sonnet 4.5 or Gemini 3.1 Flash?

Claude Sonnet 4.5 leads Gemini 3.1 Flash on 3 of the tracked benchmarks (GPQA Diamond, SWE-Bench Verified, MMMU). Claude Sonnet 4.5 shipped 150 days before Gemini 3.1 Flash, 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 Gemini 3.1 Flash released?
Gemini 3.1 Flash was released by Google on Feb 26 2026.

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