Head-to-head comparison across 4benchmark categories. Overall scores shown here use BenchLM's provisional ranking lane.
Claude Sonnet 4.5
68
Kimi K2.5 (Reasoning)
79
Pick Kimi K2.5 (Reasoning) if you want the stronger benchmark profile. Claude Sonnet 4.5 only becomes the better choice if agentic is the priority or you need the larger 200K context window.
Agentic
+0.7 difference
Coding
+0.4 difference
Knowledge
+3.9 difference
Math
+9.1 difference
Claude Sonnet 4.5
Kimi K2.5 (Reasoning)
$3 / $15
$null / $null
N/A
N/A
N/A
N/A
200K
128K
Pick Kimi K2.5 (Reasoning) if you want the stronger benchmark profile. Claude Sonnet 4.5 only becomes the better choice if agentic is the priority or you need the larger 200K context window.
Kimi K2.5 (Reasoning) is clearly ahead on the provisional aggregate, 79 to 68. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.
Kimi K2.5 (Reasoning)'s sharpest advantage is in mathematics, where it averages 96.1 against 87. The single biggest benchmark swing on the page is AIME 2025, 87% to 96.1%. Claude Sonnet 4.5 does hit back in agentic, so the answer changes if that is the part of the workload you care about most.
Kimi K2.5 (Reasoning) 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 128K for Kimi K2.5 (Reasoning).
Kimi K2.5 (Reasoning) is ahead on BenchLM's provisional leaderboard, 79 to 68. The biggest single separator in this matchup is AIME 2025, where the scores are 87% and 96.1%.
Kimi K2.5 (Reasoning) has the edge for knowledge tasks in this comparison, averaging 87.3 versus 83.4. Inside this category, GPQA is the benchmark that creates the most daylight between them.
Claude Sonnet 4.5 has the edge for coding in this comparison, averaging 77.2 versus 76.8. Inside this category, SWE-bench Verified is the benchmark that creates the most daylight between them.
Kimi K2.5 (Reasoning) has the edge for math in this comparison, averaging 96.1 versus 87. Inside this category, AIME 2025 is the benchmark that creates the most daylight between them.
Claude Sonnet 4.5 has the edge for agentic tasks in this comparison, averaging 55.3 versus 54.6. Inside this category, Terminal-Bench 2.0 is the benchmark that creates the most daylight between them.
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