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 64. 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 mathematics, where it averages 84.5 against 76.1. The single biggest benchmark swing on the page is MMMU-Pro, 64 to 81. Claude 4 Sonnet 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 4 Sonnet.
Pick Step 3.5 Flash if you want the stronger benchmark profile. Claude 4 Sonnet only becomes the better choice if multimodal & grounded is the priority.
Step 3.5 Flash
60.2
Claude 4 Sonnet
57.9
Step 3.5 Flash
47.1
Claude 4 Sonnet
42.9
Step 3.5 Flash
66.7
Claude 4 Sonnet
79.7
Step 3.5 Flash
78.3
Claude 4 Sonnet
71.8
Step 3.5 Flash
60.8
Claude 4 Sonnet
56.8
Step 3.5 Flash
87
Claude 4 Sonnet
83
Step 3.5 Flash
82.8
Claude 4 Sonnet
82.1
Step 3.5 Flash
84.5
Claude 4 Sonnet
76.1
Step 3.5 Flash is ahead overall, 66 to 64. The biggest single separator in this matchup is MMMU-Pro, where the scores are 64 and 81.
Step 3.5 Flash has the edge for knowledge tasks in this comparison, averaging 60.8 versus 56.8. Inside this category, MMLU is the benchmark that creates the most daylight between them.
Step 3.5 Flash has the edge for coding in this comparison, averaging 47.1 versus 42.9. Inside this category, HumanEval is the benchmark that creates the most daylight between them.
Step 3.5 Flash has the edge for math in this comparison, averaging 84.5 versus 76.1. Inside this category, AIME 2023 is the benchmark that creates the most daylight between them.
Step 3.5 Flash has the edge for reasoning in this comparison, averaging 78.3 versus 71.8. Inside this category, MuSR is the benchmark that creates the most daylight between them.
Step 3.5 Flash has the edge for agentic tasks in this comparison, averaging 60.2 versus 57.9. Inside this category, Terminal-Bench 2.0 is the benchmark that creates the most daylight between them.
Claude 4 Sonnet has the edge for multimodal and grounded tasks in this comparison, averaging 79.7 versus 66.7. Inside this category, MMMU-Pro is the benchmark that creates the most daylight between them.
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.
Step 3.5 Flash has the edge for multilingual tasks in this comparison, averaging 82.8 versus 82.1. Inside this category, MGSM is the benchmark that creates the most daylight between them.
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