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 58. 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 23.1. The single biggest benchmark swing on the page is AIME 2024, 87 to 23.1. GPT-4.1 mini does hit back in multimodal & grounded, so the answer changes if that is the part of the workload you care about most.
GPT-4.1 mini is also the more expensive model on tokens at $0.40 input / $1.60 output per 1M tokens, versus $0.10 input / $0.30 output per 1M tokens for Step 3.5 Flash. That is roughly 5.3x on output cost alone. GPT-4.1 mini gives you the larger context window at 1M, compared with 256K for Step 3.5 Flash.
Pick Step 3.5 Flash if you want the stronger benchmark profile. GPT-4.1 mini only becomes the better choice if multimodal & grounded is the priority or you need the larger 1M context window.
Step 3.5 Flash
60.2
GPT-4.1 mini
56.5
Step 3.5 Flash
47.1
GPT-4.1 mini
28.8
Step 3.5 Flash
66.7
GPT-4.1 mini
69.6
Step 3.5 Flash
78.3
GPT-4.1 mini
80.9
Step 3.5 Flash
60.8
GPT-4.1 mini
62.4
Step 3.5 Flash
87
GPT-4.1 mini
88.5
Step 3.5 Flash
82.8
GPT-4.1 mini
72
Step 3.5 Flash
84.5
GPT-4.1 mini
23.1
Step 3.5 Flash is ahead overall, 66 to 58. The biggest single separator in this matchup is AIME 2024, where the scores are 87 and 23.1.
GPT-4.1 mini has the edge for knowledge tasks in this comparison, averaging 62.4 versus 60.8. Inside this category, GPQA 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 28.8. Inside this category, SWE-bench Verified 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 23.1. Inside this category, AIME 2024 is the benchmark that creates the most daylight between them.
GPT-4.1 mini has the edge for reasoning in this comparison, averaging 80.9 versus 78.3. Inside this category, MRCRv2 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 56.5. Inside this category, Terminal-Bench 2.0 is the benchmark that creates the most daylight between them.
GPT-4.1 mini has the edge for multimodal and grounded tasks in this comparison, averaging 69.6 versus 66.7. Inside this category, OfficeQA Pro is the benchmark that creates the most daylight between them.
GPT-4.1 mini has the edge for instruction following in this comparison, averaging 88.5 versus 87. 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 72. Inside this category, MMLU-ProX is the benchmark that creates the most daylight between them.
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