Step 3.5 Flash vs Claude 3 Opus

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 51. 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 19. The single biggest benchmark swing on the page is SWE-bench Verified, 48 to 10. Claude 3 Opus 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 Claude 3 Opus.

Quick Verdict

Pick Step 3.5 Flash if you want the stronger benchmark profile. Claude 3 Opus only becomes the better choice if multimodal & grounded is the priority.

Agentic

Step 3.5 Flash

Step 3.5 Flash

60.2

Claude 3 Opus

48.1

62
Terminal-Bench 2.0
44
66
BrowseComp
56
54
OSWorld-Verified
47

Coding

Step 3.5 Flash

Step 3.5 Flash

47.1

Claude 3 Opus

19

77
HumanEval
53
48
SWE-bench Verified
10
45
LiveCodeBench
20
49
SWE-bench Pro
20

Multimodal & Grounded

Claude 3 Opus

Step 3.5 Flash

66.7

Claude 3 Opus

70.3

64
MMMU-Pro
73
70
OfficeQA Pro
67

Reasoning

Step 3.5 Flash

Step 3.5 Flash

78.3

Claude 3 Opus

61.6

82
SimpleQA
59
82
MuSR
57
83
BBH
74
74
LongBench v2
62
73
MRCRv2
63

Knowledge

Step 3.5 Flash

Step 3.5 Flash

60.8

Claude 3 Opus

45

84
MMLU
61
83
GPQA
61
81
SuperGPQA
59
79
OpenBookQA
57
76
MMLU-Pro
62
12
HLE
1
71
FrontierScience
56

Instruction Following

Step 3.5 Flash

Step 3.5 Flash

87

Claude 3 Opus

77

87
IFEval
77

Multilingual

Step 3.5 Flash

Step 3.5 Flash

82.8

Claude 3 Opus

69.8

86
MGSM
73
81
MMLU-ProX
68

Mathematics

Step 3.5 Flash

Step 3.5 Flash

84.5

Claude 3 Opus

65.9

85
AIME 2023
61
87
AIME 2024
63
86
AIME 2025
62
81
HMMT Feb 2023
57
83
HMMT Feb 2024
59
82
HMMT Feb 2025
58
84
BRUMO 2025
60
85
MATH-500
73

Frequently Asked Questions

Which is better, Step 3.5 Flash or Claude 3 Opus?

Step 3.5 Flash is ahead overall, 66 to 51. The biggest single separator in this matchup is SWE-bench Verified, where the scores are 48 and 10.

Which is better for knowledge tasks, Step 3.5 Flash or Claude 3 Opus?

Step 3.5 Flash has the edge for knowledge tasks in this comparison, averaging 60.8 versus 45. Inside this category, MMLU is the benchmark that creates the most daylight between them.

Which is better for coding, Step 3.5 Flash or Claude 3 Opus?

Step 3.5 Flash has the edge for coding in this comparison, averaging 47.1 versus 19. 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 Claude 3 Opus?

Step 3.5 Flash has the edge for math in this comparison, averaging 84.5 versus 65.9. 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 Claude 3 Opus?

Step 3.5 Flash has the edge for reasoning in this comparison, averaging 78.3 versus 61.6. 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 Claude 3 Opus?

Step 3.5 Flash has the edge for agentic tasks in this comparison, averaging 60.2 versus 48.1. 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 Claude 3 Opus?

Claude 3 Opus has the edge for multimodal and grounded tasks in this comparison, averaging 70.3 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 Claude 3 Opus?

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 Claude 3 Opus?

Step 3.5 Flash has the edge for multilingual tasks in this comparison, averaging 82.8 versus 69.8. Inside this category, MGSM is the benchmark that creates the most daylight between them.

Last updated: March 12, 2026

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