Side-by-side benchmark comparison across agentic, coding, multimodal, knowledge, reasoning, and math workflows.
o3 is clearly ahead on the aggregate, 70 to 65. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.
o3's sharpest advantage is in knowledge, where it averages 66 against 57.2. The single biggest benchmark swing on the page is SWE-bench Pro, 58 to 43.
o3 is also the more expensive model on tokens at $10.00 input / $40.00 output per 1M tokens, versus $0.25 input / $0.75 output per 1M tokens for Mercury 2. That is roughly 53.3x on output cost alone. o3 gives you the larger context window at 200K, compared with 128K for Mercury 2.
Pick o3 if you want the stronger benchmark profile. Mercury 2 only becomes the better choice if you want the cheaper token bill.
o3
69.9
Mercury 2
63.7
o3
49.1
Mercury 2
41.1
o3
72.3
Mercury 2
68.3
o3
82.6
Mercury 2
80.1
o3
66
Mercury 2
57.2
o3
85
Mercury 2
84
o3
81.1
Mercury 2
79.7
o3
87.5
Mercury 2
80.9
o3 is ahead overall, 70 to 65. The biggest single separator in this matchup is SWE-bench Pro, where the scores are 58 and 43.
o3 has the edge for knowledge tasks in this comparison, averaging 66 versus 57.2. Inside this category, HLE is the benchmark that creates the most daylight between them.
o3 has the edge for coding in this comparison, averaging 49.1 versus 41.1. Inside this category, SWE-bench Pro is the benchmark that creates the most daylight between them.
o3 has the edge for math in this comparison, averaging 87.5 versus 80.9. Inside this category, AIME 2023 is the benchmark that creates the most daylight between them.
o3 has the edge for reasoning in this comparison, averaging 82.6 versus 80.1. Inside this category, LongBench v2 is the benchmark that creates the most daylight between them.
o3 has the edge for agentic tasks in this comparison, averaging 69.9 versus 63.7. Inside this category, Terminal-Bench 2.0 is the benchmark that creates the most daylight between them.
o3 has the edge for multimodal and grounded tasks in this comparison, averaging 72.3 versus 68.3. Inside this category, MMMU-Pro is the benchmark that creates the most daylight between them.
o3 has the edge for instruction following in this comparison, averaging 85 versus 84. Inside this category, IFEval is the benchmark that creates the most daylight between them.
o3 has the edge for multilingual tasks in this comparison, averaging 81.1 versus 79.7. Inside this category, MGSM is the benchmark that creates the most daylight between them.
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