Side-by-side benchmark comparison across agentic, coding, multimodal, knowledge, reasoning, and math workflows.
Claude Sonnet 4.5 is clearly ahead on the aggregate, 76 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 multimodal & grounded, where it averages 91.4 against 32.4. The single biggest benchmark swing on the page is HumanEval, 87 to 17.
Claude Sonnet 4.5 is also the more expensive model on tokens at $3.00 input / $15.00 output per 1M tokens, versus $0.00 input / $0.00 output per 1M tokens for LFM2.5-1.2B-Thinking. That is roughly Infinityx on output cost alone. LFM2.5-1.2B-Thinking 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. Claude Sonnet 4.5 gives you the larger context window at 200K, compared with 32K for LFM2.5-1.2B-Thinking.
Pick Claude Sonnet 4.5 if you want the stronger benchmark profile. LFM2.5-1.2B-Thinking only becomes the better choice if you want the cheaper token bill or you want the stronger reasoning-first profile.
Claude Sonnet 4.5
70.3
LFM2.5-1.2B-Thinking
34.1
Claude Sonnet 4.5
57.5
LFM2.5-1.2B-Thinking
8.2
Claude Sonnet 4.5
91.4
LFM2.5-1.2B-Thinking
32.4
Claude Sonnet 4.5
86
LFM2.5-1.2B-Thinking
38.4
Claude Sonnet 4.5
70.7
LFM2.5-1.2B-Thinking
27
Claude Sonnet 4.5
90
LFM2.5-1.2B-Thinking
72
Claude Sonnet 4.5
88.4
LFM2.5-1.2B-Thinking
60.7
Claude Sonnet 4.5
92.4
LFM2.5-1.2B-Thinking
42.3
Claude Sonnet 4.5 is ahead overall, 76 to 33. The biggest single separator in this matchup is HumanEval, where the scores are 87 and 17.
Claude Sonnet 4.5 has the edge for knowledge tasks in this comparison, averaging 70.7 versus 27. Inside this category, MMLU is the benchmark that creates the most daylight between them.
Claude Sonnet 4.5 has the edge for coding in this comparison, averaging 57.5 versus 8.2. Inside this category, HumanEval is the benchmark that creates the most daylight between them.
Claude Sonnet 4.5 has the edge for math in this comparison, averaging 92.4 versus 42.3. Inside this category, AIME 2023 is the benchmark that creates the most daylight between them.
Claude Sonnet 4.5 has the edge for reasoning in this comparison, averaging 86 versus 38.4. Inside this category, SimpleQA is the benchmark that creates the most daylight between them.
Claude Sonnet 4.5 has the edge for agentic tasks in this comparison, averaging 70.3 versus 34.1. Inside this category, BrowseComp is the benchmark that creates the most daylight between them.
Claude Sonnet 4.5 has the edge for multimodal and grounded tasks in this comparison, averaging 91.4 versus 32.4. Inside this category, MMMU-Pro is the benchmark that creates the most daylight between them.
Claude Sonnet 4.5 has the edge for instruction following in this comparison, averaging 90 versus 72. Inside this category, IFEval is the benchmark that creates the most daylight between them.
Claude Sonnet 4.5 has the edge for multilingual tasks in this comparison, averaging 88.4 versus 60.7. Inside this category, MGSM is the benchmark that creates the most daylight between them.
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