Step 3.5 Flash vs GPT-4.1 nano

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

Step 3.5 Flash is clearly ahead on the aggregate, 66 to 49. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.

Step 3.5 Flash's sharpest advantage is in mathematics, where it averages 84.5 against 9.8. The single biggest benchmark swing on the page is AIME 2024, 87 to 9.8.

GPT-4.1 nano is also the more expensive model on tokens at $0.10 input / $0.40 output per 1M tokens, versus $0.10 input / $0.30 output per 1M tokens for Step 3.5 Flash. GPT-4.1 nano gives you the larger context window at 1M, compared with 256K for Step 3.5 Flash.

Quick Verdict

Pick Step 3.5 Flash if you want the stronger benchmark profile. GPT-4.1 nano only becomes the better choice if you need the larger 1M context window.

Agentic

Step 3.5 Flash

Step 3.5 Flash

60.2

GPT-4.1 nano

47.4

62
Terminal-Bench 2.0
43
66
BrowseComp
62
54
OSWorld-Verified
42

Coding

Step 3.5 Flash

Step 3.5 Flash

47.1

GPT-4.1 nano

18

77
HumanEval
Coming soon
48
SWE-bench Verified
Coming soon
45
LiveCodeBench
Coming soon
49
SWE-bench Pro
18

Multimodal & Grounded

Step 3.5 Flash

Step 3.5 Flash

66.7

GPT-4.1 nano

59.3

64
MMMU-Pro
53
70
OfficeQA Pro
67

Reasoning

Step 3.5 Flash

Step 3.5 Flash

78.3

GPT-4.1 nano

74.1

82
SimpleQA
Coming soon
82
MuSR
Coming soon
83
BBH
Coming soon
74
LongBench v2
75
73
MRCRv2
73

Knowledge

Step 3.5 Flash

Step 3.5 Flash

60.8

GPT-4.1 nano

50.7

84
MMLU
80.1
83
GPQA
50.3
81
SuperGPQA
Coming soon
79
OpenBookQA
Coming soon
76
MMLU-Pro
Coming soon
12
HLE
Coming soon
71
FrontierScience
51

Instruction Following

Step 3.5 Flash

Step 3.5 Flash

87

GPT-4.1 nano

83.2

87
IFEval
83.2

Multilingual

Step 3.5 Flash

Step 3.5 Flash

82.8

GPT-4.1 nano

59

86
MGSM
Coming soon
81
MMLU-ProX
59

Mathematics

Step 3.5 Flash

Step 3.5 Flash

84.5

GPT-4.1 nano

9.8

85
AIME 2023
Coming soon
87
AIME 2024
9.8
86
AIME 2025
Coming soon
81
HMMT Feb 2023
Coming soon
83
HMMT Feb 2024
Coming soon
82
HMMT Feb 2025
Coming soon
84
BRUMO 2025
Coming soon
85
MATH-500
Coming soon

Frequently Asked Questions

Which is better, Step 3.5 Flash or GPT-4.1 nano?

Step 3.5 Flash is ahead overall, 66 to 49. The biggest single separator in this matchup is AIME 2024, where the scores are 87 and 9.8.

Which is better for knowledge tasks, Step 3.5 Flash or GPT-4.1 nano?

Step 3.5 Flash has the edge for knowledge tasks in this comparison, averaging 60.8 versus 50.7. Inside this category, GPQA is the benchmark that creates the most daylight between them.

Which is better for coding, Step 3.5 Flash or GPT-4.1 nano?

Step 3.5 Flash has the edge for coding in this comparison, averaging 47.1 versus 18. Inside this category, SWE-bench Pro is the benchmark that creates the most daylight between them.

Which is better for math, Step 3.5 Flash or GPT-4.1 nano?

Step 3.5 Flash has the edge for math in this comparison, averaging 84.5 versus 9.8. Inside this category, AIME 2024 is the benchmark that creates the most daylight between them.

Which is better for reasoning, Step 3.5 Flash or GPT-4.1 nano?

Step 3.5 Flash has the edge for reasoning in this comparison, averaging 78.3 versus 74.1. Inside this category, LongBench v2 is the benchmark that creates the most daylight between them.

Which is better for agentic tasks, Step 3.5 Flash or GPT-4.1 nano?

Step 3.5 Flash has the edge for agentic tasks in this comparison, averaging 60.2 versus 47.4. Inside this category, Terminal-Bench 2.0 is the benchmark that creates the most daylight between them.

Which is better for multimodal and grounded tasks, Step 3.5 Flash or GPT-4.1 nano?

Step 3.5 Flash has the edge for multimodal and grounded tasks in this comparison, averaging 66.7 versus 59.3. Inside this category, MMMU-Pro is the benchmark that creates the most daylight between them.

Which is better for instruction following, Step 3.5 Flash or GPT-4.1 nano?

Step 3.5 Flash has the edge for instruction following in this comparison, averaging 87 versus 83.2. Inside this category, IFEval is the benchmark that creates the most daylight between them.

Which is better for multilingual tasks, Step 3.5 Flash or GPT-4.1 nano?

Step 3.5 Flash has the edge for multilingual tasks in this comparison, averaging 82.8 versus 59. Inside this category, MMLU-ProX is the benchmark that creates the most daylight between them.

Last updated: March 12, 2026

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