Side-by-side benchmark comparison across knowledge, coding, math, and reasoning.
Grok 4.1 Fast is clearly ahead on the aggregate, 83 to 31. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.
Grok 4.1 Fast's sharpest advantage is in mathematics, where it averages 94.3 against 85.2. The single biggest benchmark swing on the page is GPQA, 92 to 71.2.
GPT-5 nano is the reasoning model in the pair, while Grok 4.1 Fast is not. That usually helps on harder chain-of-thought-heavy tests, but it can also mean more latency and more token spend in real use. Grok 4.1 Fast gives you the larger context window at 1M, compared with 400K for GPT-5 nano.
Pick Grok 4.1 Fast if you want the stronger benchmark profile. GPT-5 nano only becomes the better choice if you want the stronger reasoning-first profile.
Grok 4.1 Fast
77.5
GPT-5 nano
71.2
Grok 4.1 Fast
94.3
GPT-5 nano
85.2
Grok 4.1 Fast is ahead overall, 83 to 31. The biggest single separator in this matchup is GPQA, where the scores are 92 and 71.2.
Grok 4.1 Fast has the edge for knowledge tasks in this comparison, averaging 77.5 versus 71.2. Inside this category, GPQA is the benchmark that creates the most daylight between them.
Grok 4.1 Fast has the edge for math in this comparison, averaging 94.3 versus 85.2. Inside this category, AIME 2025 is the benchmark that creates the most daylight between them.
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