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GPT-5.1 vs Grok 4 Fast

3 vs 0 benchmarks won

OpenAI
GPT-5.1
xAI
Grok 4 Fast
Overview
CompanyOpenAIxAI
Release dateNov 12 2025Sep 2025
Model type
Open sourceNoNo
Specifications
Parameters
Context window
Benchmarks
Science reasoning
GPQA Diamond
88.1%
Software engineering
SWE-Bench Verified
76.3%
Multimodal understanding
MMMU
76%
Timeline
Release gapGrok 4 Fast shipped 72 days before GPT-5.1

Which is better: GPT-5.1 or Grok 4 Fast?

GPT-5.1 leads Grok 4 Fast on 3 of the tracked benchmarks (GPQA Diamond, SWE-Bench Verified, MMMU). Grok 4 Fast shipped 72 days before GPT-5.1, 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 GPT-5.1 released?
GPT-5.1 was released by OpenAI on Nov 12 2025.
When was Grok 4 Fast released?
Grok 4 Fast was released by xAI on Sep 2025.

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