Side-by-side benchmark comparison across knowledge, coding, math, and reasoning.
Claude Sonnet 4.5 is clearly ahead on the aggregate, 83 to 33. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.
Claude Sonnet 4.5's sharpest advantage is in mathematics, where it averages 95 against 86. The single biggest benchmark swing on the page is GPQA, 93 to 79. o1-pro does hit back in knowledge, so the answer changes if that is the part of the workload you care about most.
o1-pro is also the more expensive model on tokens at $150.00 input / $600.00 output per 1M tokens, versus $3.00 input / $15.00 output per 1M tokens for Claude Sonnet 4.5. That is roughly 40.0x on output cost alone. o1-pro is the reasoning model in the pair, while Claude Sonnet 4.5 is not. That usually helps on harder chain-of-thought-heavy tests, but it can also mean more latency and more token spend in real use.
Pick Claude Sonnet 4.5 if you want the stronger benchmark profile. o1-pro only becomes the better choice if knowledge is the priority or you want the stronger reasoning-first profile.
Claude Sonnet 4.5
78.8
o1-pro
79
Claude Sonnet 4.5
95
o1-pro
86
Claude Sonnet 4.5 is ahead overall, 83 to 33. The biggest single separator in this matchup is GPQA, where the scores are 93 and 79.
o1-pro has the edge for knowledge tasks in this comparison, averaging 79 versus 78.8. Inside this category, GPQA is the benchmark that creates the most daylight between them.
Claude Sonnet 4.5 has the edge for math in this comparison, averaging 95 versus 86. Inside this category, AIME 2024 is the benchmark that creates the most daylight between them.
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