Side-by-side benchmark comparison across agentic, coding, multimodal, knowledge, reasoning, and math workflows.
Gemini 2.5 Pro finishes one point ahead overall, 67 to 66. That is enough to call, but not enough to treat as a blowout. This matchup comes down to a few meaningful edges rather than one model dominating the board.
Gemini 2.5 Pro's sharpest advantage is in multimodal & grounded, where it averages 85.1 against 66.7. The single biggest benchmark swing on the page is MMMU-Pro, 86 to 64. Step 3.5 Flash does hit back in coding, so the answer changes if that is the part of the workload you care about most.
Gemini 2.5 Pro is also the more expensive model on tokens at $1.25 input / $5.00 output per 1M tokens, versus $0.10 input / $0.30 output per 1M tokens for Step 3.5 Flash. That is roughly 16.7x on output cost alone. Gemini 2.5 Pro gives you the larger context window at 1M, compared with 256K for Step 3.5 Flash.
Pick Gemini 2.5 Pro if you want the stronger benchmark profile. Step 3.5 Flash only becomes the better choice if coding is the priority or you want the cheaper token bill.
Gemini 2.5 Pro
61.7
Step 3.5 Flash
60.2
Gemini 2.5 Pro
41
Step 3.5 Flash
47.1
Gemini 2.5 Pro
85.1
Step 3.5 Flash
66.7
Gemini 2.5 Pro
80.7
Step 3.5 Flash
78.3
Gemini 2.5 Pro
58.4
Step 3.5 Flash
60.8
Gemini 2.5 Pro
83
Step 3.5 Flash
87
Gemini 2.5 Pro
82.7
Step 3.5 Flash
82.8
Gemini 2.5 Pro
83.5
Step 3.5 Flash
84.5
Gemini 2.5 Pro is ahead overall, 67 to 66. The biggest single separator in this matchup is MMMU-Pro, where the scores are 86 and 64.
Step 3.5 Flash has the edge for knowledge tasks in this comparison, averaging 60.8 versus 58.4. Inside this category, HLE 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 41. Inside this category, LiveCodeBench 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 83.5. Inside this category, AIME 2023 is the benchmark that creates the most daylight between them.
Gemini 2.5 Pro has the edge for reasoning in this comparison, averaging 80.7 versus 78.3. Inside this category, MRCRv2 is the benchmark that creates the most daylight between them.
Gemini 2.5 Pro has the edge for agentic tasks in this comparison, averaging 61.7 versus 60.2. Inside this category, BrowseComp is the benchmark that creates the most daylight between them.
Gemini 2.5 Pro has the edge for multimodal and grounded tasks in this comparison, averaging 85.1 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 82.7. Inside this category, MGSM is the benchmark that creates the most daylight between them.
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