Step 3.5 Flash vs Z-1

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 47. 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 60.9. The single biggest benchmark swing on the page is MuSR, 82 to 48.

Step 3.5 Flash gives you the larger context window at 256K, compared with 128K for Z-1.

Quick Verdict

Pick Step 3.5 Flash if you want the stronger benchmark profile. Z-1 only becomes the better choice if its workflow or ecosystem matters more than the raw scoreboard.

Agentic

Step 3.5 Flash

Step 3.5 Flash

60.2

Z-1

42.2

62
Terminal-Bench 2.0
39
66
BrowseComp
49
54
OSWorld-Verified
41

Coding

Step 3.5 Flash

Step 3.5 Flash

47.1

Z-1

26.7

77
HumanEval
44
48
SWE-bench Verified
33
45
LiveCodeBench
22
49
SWE-bench Pro
30

Multimodal & Grounded

Step 3.5 Flash

Step 3.5 Flash

66.7

Z-1

50.5

64
MMMU-Pro
46
70
OfficeQA Pro
56

Reasoning

Step 3.5 Flash

Step 3.5 Flash

78.3

Z-1

54.8

82
SimpleQA
50
82
MuSR
48
83
BBH
74
74
LongBench v2
56
73
MRCRv2
57

Knowledge

Step 3.5 Flash

Step 3.5 Flash

60.8

Z-1

42.7

84
MMLU
52
83
GPQA
51
81
SuperGPQA
49
79
OpenBookQA
47
76
MMLU-Pro
64
12
HLE
6
71
FrontierScience
51

Instruction Following

Step 3.5 Flash

Step 3.5 Flash

87

Z-1

80

87
IFEval
80

Multilingual

Step 3.5 Flash

Step 3.5 Flash

82.8

Z-1

72.7

86
MGSM
74
81
MMLU-ProX
72

Mathematics

Step 3.5 Flash

Step 3.5 Flash

84.5

Z-1

60.9

85
AIME 2023
52
87
AIME 2024
54
86
AIME 2025
53
81
HMMT Feb 2023
48
83
HMMT Feb 2024
50
82
HMMT Feb 2025
49
84
BRUMO 2025
51
85
MATH-500
73

Frequently Asked Questions

Which is better, Step 3.5 Flash or Z-1?

Step 3.5 Flash is ahead overall, 66 to 47. The biggest single separator in this matchup is MuSR, where the scores are 82 and 48.

Which is better for knowledge tasks, Step 3.5 Flash or Z-1?

Step 3.5 Flash has the edge for knowledge tasks in this comparison, averaging 60.8 versus 42.7. Inside this category, MMLU is the benchmark that creates the most daylight between them.

Which is better for coding, Step 3.5 Flash or Z-1?

Step 3.5 Flash has the edge for coding in this comparison, averaging 47.1 versus 26.7. Inside this category, HumanEval is the benchmark that creates the most daylight between them.

Which is better for math, Step 3.5 Flash or Z-1?

Step 3.5 Flash has the edge for math in this comparison, averaging 84.5 versus 60.9. 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 Z-1?

Step 3.5 Flash has the edge for reasoning in this comparison, averaging 78.3 versus 54.8. 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 Z-1?

Step 3.5 Flash has the edge for agentic tasks in this comparison, averaging 60.2 versus 42.2. 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 Z-1?

Step 3.5 Flash has the edge for multimodal and grounded tasks in this comparison, averaging 66.7 versus 50.5. 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 Z-1?

Step 3.5 Flash has the edge for instruction following in this comparison, averaging 87 versus 80. 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 Z-1?

Step 3.5 Flash has the edge for multilingual tasks in this comparison, averaging 82.8 versus 72.7. Inside this category, MGSM is the benchmark that creates the most daylight between them.

Last updated: March 12, 2026

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