Step 3.5 Flash vs o4-mini (high)

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

Step 3.5 Flash has the cleaner overall profile here, landing at 66 versus 63. It is a real lead, but still close enough that category-level strengths matter more than the headline number.

Step 3.5 Flash's sharpest advantage is in coding, where it averages 47.1 against 38.7. The single biggest benchmark swing on the page is LiveCodeBench, 45 to 34. o4-mini (high) does hit back in multimodal & grounded, so the answer changes if that is the part of the workload you care about most.

Step 3.5 Flash gives you the larger context window at 256K, compared with 200K for o4-mini (high).

Quick Verdict

Pick Step 3.5 Flash if you want the stronger benchmark profile. o4-mini (high) only becomes the better choice if multimodal & grounded is the priority.

Agentic

Step 3.5 Flash

Step 3.5 Flash

60.2

o4-mini (high)

58.5

62
Terminal-Bench 2.0
58
66
BrowseComp
64
54
OSWorld-Verified
55

Coding

Step 3.5 Flash

Step 3.5 Flash

47.1

o4-mini (high)

38.7

77
HumanEval
74
48
SWE-bench Verified
45
45
LiveCodeBench
34
49
SWE-bench Pro
42

Multimodal & Grounded

o4-mini (high)

Step 3.5 Flash

66.7

o4-mini (high)

68.3

64
MMMU-Pro
66
70
OfficeQA Pro
71

Reasoning

Step 3.5 Flash

Step 3.5 Flash

78.3

o4-mini (high)

77.4

82
SimpleQA
80
82
MuSR
78
83
BBH
83
74
LongBench v2
75
73
MRCRv2
74

Knowledge

o4-mini (high)

Step 3.5 Flash

60.8

o4-mini (high)

61.2

84
MMLU
82
83
GPQA
82
81
SuperGPQA
80
79
OpenBookQA
78
76
MMLU-Pro
76
12
HLE
13
71
FrontierScience
73

Instruction Following

Step 3.5 Flash

Step 3.5 Flash

87

o4-mini (high)

83

87
IFEval
83

Multilingual

Step 3.5 Flash

Step 3.5 Flash

82.8

o4-mini (high)

81.7

86
MGSM
83
81
MMLU-ProX
81

Mathematics

Step 3.5 Flash

Step 3.5 Flash

84.5

o4-mini (high)

82.9

85
AIME 2023
83
87
AIME 2024
85
86
AIME 2025
84
81
HMMT Feb 2023
79
83
HMMT Feb 2024
81
82
HMMT Feb 2025
80
84
BRUMO 2025
82
85
MATH-500
84

Frequently Asked Questions

Which is better, Step 3.5 Flash or o4-mini (high)?

Step 3.5 Flash is ahead overall, 66 to 63. The biggest single separator in this matchup is LiveCodeBench, where the scores are 45 and 34.

Which is better for knowledge tasks, Step 3.5 Flash or o4-mini (high)?

o4-mini (high) has the edge for knowledge tasks in this comparison, averaging 61.2 versus 60.8. Inside this category, MMLU is the benchmark that creates the most daylight between them.

Which is better for coding, Step 3.5 Flash or o4-mini (high)?

Step 3.5 Flash has the edge for coding in this comparison, averaging 47.1 versus 38.7. Inside this category, LiveCodeBench is the benchmark that creates the most daylight between them.

Which is better for math, Step 3.5 Flash or o4-mini (high)?

Step 3.5 Flash has the edge for math in this comparison, averaging 84.5 versus 82.9. Inside this category, AIME 2023 is the benchmark that creates the most daylight between them.

Which is better for reasoning, Step 3.5 Flash or o4-mini (high)?

Step 3.5 Flash has the edge for reasoning in this comparison, averaging 78.3 versus 77.4. Inside this category, MuSR is the benchmark that creates the most daylight between them.

Which is better for agentic tasks, Step 3.5 Flash or o4-mini (high)?

Step 3.5 Flash has the edge for agentic tasks in this comparison, averaging 60.2 versus 58.5. 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 o4-mini (high)?

o4-mini (high) has the edge for multimodal and grounded tasks in this comparison, averaging 68.3 versus 66.7. 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 o4-mini (high)?

Step 3.5 Flash has the edge for instruction following in this comparison, averaging 87 versus 83. 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 o4-mini (high)?

Step 3.5 Flash has the edge for multilingual tasks in this comparison, averaging 82.8 versus 81.7. Inside this category, MGSM is the benchmark that creates the most daylight between them.

Last updated: March 12, 2026

Weekly LLM Benchmark Digest

Get notified when new models drop, benchmark scores change, or the leaderboard shifts. One email per week.

Free. No spam. Unsubscribe anytime. We only store derived location metadata for consent routing.