o1-preview vs GPT-5 nano

Side-by-side benchmark comparison across knowledge, coding, math, and reasoning.

o1-preview 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.

o1-preview's sharpest advantage is in mathematics, where it averages 93.1 against 85.2. The single biggest benchmark swing on the page is GPQA, 90 to 71.2.

GPT-5 nano gives you the larger context window at 400K, compared with 200K for o1-preview.

Quick Verdict

Pick o1-preview if you want the stronger benchmark profile. GPT-5 nano only becomes the better choice if you need the larger 400K context window.

Knowledge

o1-preview

o1-preview

78

GPT-5 nano

71.2

92
MMLU
-
90
GPQA
71.2
88
SuperGPQA
-
86
OpenBookQA
-
80
MMLU-Pro
-
32
HLE
-

Coding

o1-preview
86
HumanEval
-
65
SWE-bench Verified
-
60
LiveCodeBench
-

Mathematics

o1-preview

o1-preview

93.1

GPT-5 nano

85.2

94
AIME 2023
-
96
AIME 2024
-
95
AIME 2025
85.2
90
HMMT Feb 2023
-
92
HMMT Feb 2024
-
91
HMMT Feb 2025
-
93
BRUMO 2025
-
94
MATH-500
-

Reasoning

o1-preview
88
SimpleQA
-
86
MuSR
-
93
BBH
-

Instruction Following

o1-preview
88
IFEval
-

Multilingual

o1-preview
90
MGSM
-

Frequently Asked Questions

Which is better, o1-preview or GPT-5 nano?

o1-preview is ahead overall, 83 to 31. The biggest single separator in this matchup is GPQA, where the scores are 90 and 71.2.

Which is better for knowledge tasks, o1-preview or GPT-5 nano?

o1-preview has the edge for knowledge tasks in this comparison, averaging 78 versus 71.2. Inside this category, GPQA is the benchmark that creates the most daylight between them.

Which is better for math, o1-preview or GPT-5 nano?

o1-preview has the edge for math in this comparison, averaging 93.1 versus 85.2. Inside this category, AIME 2025 is the benchmark that creates the most daylight between them.

Last updated: March 9, 2026

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