Side-by-side benchmark comparison across agentic, coding, multimodal, knowledge, reasoning, and math workflows.
Claude Opus 4.5 is clearly ahead on the aggregate, 77 to 65. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.
Claude Opus 4.5's sharpest advantage is in multimodal & grounded, where it averages 90.9 against 68.3. The single biggest benchmark swing on the page is MMMU-Pro, 94 to 66.
Mercury 2 is the reasoning model in the pair, while Claude Opus 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. Claude Opus 4.5 gives you the larger context window at 200K, compared with 128K for Mercury 2.
Pick Claude Opus 4.5 if you want the stronger benchmark profile. Mercury 2 only becomes the better choice if you want the stronger reasoning-first profile.
Claude Opus 4.5
70.5
Mercury 2
63.7
Claude Opus 4.5
60.4
Mercury 2
41.1
Claude Opus 4.5
90.9
Mercury 2
68.3
Claude Opus 4.5
87.7
Mercury 2
80.1
Claude Opus 4.5
70.9
Mercury 2
57.2
Claude Opus 4.5
90
Mercury 2
84
Claude Opus 4.5
86.1
Mercury 2
79.7
Claude Opus 4.5
93.2
Mercury 2
80.9
Claude Opus 4.5 is ahead overall, 77 to 65. The biggest single separator in this matchup is MMMU-Pro, where the scores are 94 and 66.
Claude Opus 4.5 has the edge for knowledge tasks in this comparison, averaging 70.9 versus 57.2. Inside this category, MMLU is the benchmark that creates the most daylight between them.
Claude Opus 4.5 has the edge for coding in this comparison, averaging 60.4 versus 41.1. Inside this category, SWE-bench Verified is the benchmark that creates the most daylight between them.
Claude Opus 4.5 has the edge for math in this comparison, averaging 93.2 versus 80.9. Inside this category, AIME 2023 is the benchmark that creates the most daylight between them.
Claude Opus 4.5 has the edge for reasoning in this comparison, averaging 87.7 versus 80.1. Inside this category, SimpleQA is the benchmark that creates the most daylight between them.
Claude Opus 4.5 has the edge for agentic tasks in this comparison, averaging 70.5 versus 63.7. Inside this category, Terminal-Bench 2.0 is the benchmark that creates the most daylight between them.
Claude Opus 4.5 has the edge for multimodal and grounded tasks in this comparison, averaging 90.9 versus 68.3. Inside this category, MMMU-Pro is the benchmark that creates the most daylight between them.
Claude Opus 4.5 has the edge for instruction following in this comparison, averaging 90 versus 84. Inside this category, IFEval is the benchmark that creates the most daylight between them.
Claude Opus 4.5 has the edge for multilingual tasks in this comparison, averaging 86.1 versus 79.7. Inside this category, MGSM is the benchmark that creates the most daylight between them.
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