Step 3.5 Flash vs Gemini 1.5 Pro

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 52. 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 coding, where it averages 47.1 against 18.5. The single biggest benchmark swing on the page is SWE-bench Verified, 48 to 5. Gemini 1.5 Pro does hit back in multimodal & grounded, so the answer changes if that is the part of the workload you care about most.

Gemini 1.5 Pro gives you the larger context window at 2M, compared with 256K for Step 3.5 Flash.

Quick Verdict

Pick Step 3.5 Flash if you want the stronger benchmark profile. Gemini 1.5 Pro only becomes the better choice if multimodal & grounded is the priority or you need the larger 2M context window.

Agentic

Step 3.5 Flash

Step 3.5 Flash

60.2

Gemini 1.5 Pro

49.8

62
Terminal-Bench 2.0
45
66
BrowseComp
64
54
OSWorld-Verified
45

Coding

Step 3.5 Flash

Step 3.5 Flash

47.1

Gemini 1.5 Pro

18.5

77
HumanEval
56
48
SWE-bench Verified
5
45
LiveCodeBench
22
49
SWE-bench Pro
18

Multimodal & Grounded

Gemini 1.5 Pro

Step 3.5 Flash

66.7

Gemini 1.5 Pro

74.1

64
MMMU-Pro
75
70
OfficeQA Pro
73

Reasoning

Step 3.5 Flash

Step 3.5 Flash

78.3

Gemini 1.5 Pro

66.9

82
SimpleQA
62
82
MuSR
60
83
BBH
74
74
LongBench v2
70
73
MRCRv2
73

Knowledge

Step 3.5 Flash

Step 3.5 Flash

60.8

Gemini 1.5 Pro

44.2

84
MMLU
64
83
GPQA
64
81
SuperGPQA
62
79
OpenBookQA
60
76
MMLU-Pro
57
12
HLE
1
71
FrontierScience
54

Instruction Following

Step 3.5 Flash

Step 3.5 Flash

87

Gemini 1.5 Pro

77

87
IFEval
77

Multilingual

Step 3.5 Flash

Step 3.5 Flash

82.8

Gemini 1.5 Pro

69.5

86
MGSM
76
81
MMLU-ProX
66

Mathematics

Step 3.5 Flash

Step 3.5 Flash

84.5

Gemini 1.5 Pro

67.5

85
AIME 2023
64
87
AIME 2024
66
86
AIME 2025
65
81
HMMT Feb 2023
60
83
HMMT Feb 2024
62
82
HMMT Feb 2025
61
84
BRUMO 2025
63
85
MATH-500
73

Frequently Asked Questions

Which is better, Step 3.5 Flash or Gemini 1.5 Pro?

Step 3.5 Flash is ahead overall, 66 to 52. The biggest single separator in this matchup is SWE-bench Verified, where the scores are 48 and 5.

Which is better for knowledge tasks, Step 3.5 Flash or Gemini 1.5 Pro?

Step 3.5 Flash has the edge for knowledge tasks in this comparison, averaging 60.8 versus 44.2. Inside this category, MMLU is the benchmark that creates the most daylight between them.

Which is better for coding, Step 3.5 Flash or Gemini 1.5 Pro?

Step 3.5 Flash has the edge for coding in this comparison, averaging 47.1 versus 18.5. Inside this category, SWE-bench Verified is the benchmark that creates the most daylight between them.

Which is better for math, Step 3.5 Flash or Gemini 1.5 Pro?

Step 3.5 Flash has the edge for math in this comparison, averaging 84.5 versus 67.5. 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 Gemini 1.5 Pro?

Step 3.5 Flash has the edge for reasoning in this comparison, averaging 78.3 versus 66.9. 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 Gemini 1.5 Pro?

Step 3.5 Flash has the edge for agentic tasks in this comparison, averaging 60.2 versus 49.8. 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 Gemini 1.5 Pro?

Gemini 1.5 Pro has the edge for multimodal and grounded tasks in this comparison, averaging 74.1 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 Gemini 1.5 Pro?

Step 3.5 Flash has the edge for instruction following in this comparison, averaging 87 versus 77. 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 Gemini 1.5 Pro?

Step 3.5 Flash has the edge for multilingual tasks in this comparison, averaging 82.8 versus 69.5. Inside this category, MMLU-ProX is the benchmark that creates the most daylight between them.

Last updated: March 12, 2026

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