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
68
Verified leaderboard positions: Claude Sonnet 4.5 unranked · Kimi K2.5 #11
Treat this as a split decision. Claude Sonnet 4.5 makes more sense if knowledge is the priority or you need the larger 200K context window; Kimi K2.5 is the better fit if reasoning is the priority or you want the cheaper token bill.
Agentic
+0.7 difference
Coding
+18.2 difference
Reasoning
+47.4 difference
Knowledge
+18.3 difference
Claude Sonnet 4.5
Kimi K2.5
$3 / $15
$0.5 / $2.8
N/A
45 t/s
N/A
2.38s
200K
128K
Treat this as a split decision. Claude Sonnet 4.5 makes more sense if knowledge is the priority or you need the larger 200K context window; Kimi K2.5 is the better fit if reasoning is the priority or you want the cheaper token bill.
Claude Sonnet 4.5 and Kimi K2.5 finish on the same provisional overall score, so this is less about a single winner and more about where the edge shows up. The provisional headline says tie; the benchmark table is where the real choice happens.
Claude Sonnet 4.5 is also the more expensive model on tokens at $3.00 input / $15.00 output per 1M tokens, versus $0.50 input / $2.80 output per 1M tokens for Kimi K2.5. That is roughly 5.4x on output cost alone. Claude Sonnet 4.5 gives you the larger context window at 200K, compared with 128K for Kimi K2.5.
Claude Sonnet 4.5 and Kimi K2.5 are tied on the provisional overall score, so the right pick depends on which category matters most for your use case.
Claude Sonnet 4.5 has the edge for knowledge tasks in this comparison, averaging 83.4 versus 65.1. 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 59. Inside this category, SWE-bench Verified is the benchmark that creates the most daylight between them.
Kimi K2.5 has the edge for reasoning in this comparison, averaging 61 versus 13.6. Claude Sonnet 4.5 stays close enough that the answer can still flip depending on your workload.
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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