Step 3.5 Flash vs Claude 3 Haiku

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 coding, where it averages 47.1 against 19.3. The single biggest benchmark swing on the page is SWE-bench Verified, 48 to 17. Claude 3 Haiku 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 Haiku.

Quick Verdict

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

Agentic

Step 3.5 Flash

Step 3.5 Flash

60.2

Claude 3 Haiku

44

62
Terminal-Bench 2.0
40
66
BrowseComp
53
54
OSWorld-Verified
42

Coding

Step 3.5 Flash

Step 3.5 Flash

47.1

Claude 3 Haiku

19.3

77
HumanEval
48
48
SWE-bench Verified
17
45
LiveCodeBench
20
49
SWE-bench Pro
19

Multimodal & Grounded

Claude 3 Haiku

Step 3.5 Flash

66.7

Claude 3 Haiku

68.7

64
MMMU-Pro
70
70
OfficeQA Pro
67

Reasoning

Step 3.5 Flash

Step 3.5 Flash

78.3

Claude 3 Haiku

59.6

82
SimpleQA
54
82
MuSR
52
83
BBH
74
74
LongBench v2
63
73
MRCRv2
63

Knowledge

Step 3.5 Flash

Step 3.5 Flash

60.8

Claude 3 Haiku

42.8

84
MMLU
56
83
GPQA
56
81
SuperGPQA
54
79
OpenBookQA
52
76
MMLU-Pro
63
12
HLE
2
71
FrontierScience
50

Instruction Following

Step 3.5 Flash

Step 3.5 Flash

87

Claude 3 Haiku

76

87
IFEval
76

Multilingual

Step 3.5 Flash

Step 3.5 Flash

82.8

Claude 3 Haiku

71.1

86
MGSM
73
81
MMLU-ProX
70

Mathematics

Step 3.5 Flash

Step 3.5 Flash

84.5

Claude 3 Haiku

62.2

85
AIME 2023
56
87
AIME 2024
58
86
AIME 2025
57
81
HMMT Feb 2023
52
83
HMMT Feb 2024
54
82
HMMT Feb 2025
53
84
BRUMO 2025
55
85
MATH-500
71

Frequently Asked Questions

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

Step 3.5 Flash is ahead overall, 66 to 49. The biggest single separator in this matchup is SWE-bench Verified, where the scores are 48 and 17.

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

Step 3.5 Flash has the edge for knowledge tasks in this comparison, averaging 60.8 versus 42.8. Inside this category, MMLU is the benchmark that creates the most daylight between them.

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

Step 3.5 Flash has the edge for coding in this comparison, averaging 47.1 versus 19.3. 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 Haiku?

Step 3.5 Flash has the edge for math in this comparison, averaging 84.5 versus 62.2. 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 Haiku?

Step 3.5 Flash has the edge for reasoning in this comparison, averaging 78.3 versus 59.6. 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 Haiku?

Step 3.5 Flash has the edge for agentic tasks in this comparison, averaging 60.2 versus 44. 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 Haiku?

Claude 3 Haiku has the edge for multimodal and grounded tasks in this comparison, averaging 68.7 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 Haiku?

Step 3.5 Flash has the edge for instruction following in this comparison, averaging 87 versus 76. 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 Haiku?

Step 3.5 Flash has the edge for multilingual tasks in this comparison, averaging 82.8 versus 71.1. Inside this category, MGSM is the benchmark that creates the most daylight between them.

Last updated: March 12, 2026

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