Grok 4.1 Fast vs OpenAI o4-mini

Compare Grok 4.1 Fast by xAI against OpenAI o4-mini by OpenAI, tested across 35 shared challenges. Updated April 2026.

Which is better, Grok 4.1 Fast or OpenAI o4-mini?

Grok 4.1 Fast and OpenAI o4-mini are both competitive models. Compare their real outputs side by side below.

Key Differences Between Grok 4.1 Fast and OpenAI o4-mini

Grok 4.1 Fast is made by xai while OpenAI o4-mini is from openai.

Our Verdict
Grok 4.1 Fast
Grok 4.1 Fast
OpenAI o4-mini
OpenAI o4-miniRunner-up

No community votes yet. On paper, Grok 4.1 Fast has the edge — bigger model tier, newer.

Too close to call
Writing DNA

Style Comparison

Similarity
93%

Grok 4.1 Fast uses 466.5x more bold

Grok 4.1 Fast
OpenAI o4-mini
67%Vocabulary73%
15wSentence Length15w
0.17Hedging0.18
4.7Bold0.0
3.7Lists2.1
0.00Emoji0.00
0.99Headings0.00
0.14Transitions0.02
Based on 24 + 10 text responses
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Grok 4.1 FastOpenAI o4-mini

279 AI models invented the same fake scientist.

We read every word. 250 models. 2.14 million words. This is what we found.

AI Hallucination Index 2026
Free preview13 of 58 slides
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