Claude Opus 5.5 vs Kimi K3.1 Pro
Wins 2 of 4 areas
Coding · Reasoning
Wins 2 of 4 areas
Agents · Images and charts
The two are evenly matched.Claude Opus 5.5 is better at coding and reasoning; Kimi K3.1 Pro at agents and images and charts.
Scores updated · 22 tests both models report · How we compare
Where each one wins
Tests won in each of the four areas where both have results. Each piece is one test, so a longer bar means more evidence; grey means the two scored within a point of each other.
Coding, agents, reasoning and images and charts rest on a single test each.
What it costs
Prices per million tokens, roughly 750,000 words. The bars show the cost of a million tokens read plus a million written.
Kimi K3.1 Pro costs 50% less for the same work.
The biggest differences
The tests each model wins by the widest margin, up to three each. Scores are out of 100.
Where Claude Opus 5.5 pulls ahead
- Very hard expert questions across many subjectsHumanity's Last Exam+10.3points ahead
Where Kimi K3.1 Pro pulls ahead
- Harder college exam questions with imagesMMMU-Pro+2.3points ahead
- Finds hard-to-locate facts by browsing the webBrowseComp+1.3points ahead
Every test, side by side
All 22 tests both models report. The winning score is in its model's colour; marks a score checked independently.
CodingClaude Opus 5.5
- LMArena · WebDevClaude Opus 5.5 by 115 rating points18101695+115 rating
ReasoningClaude Opus 5.5
- Humanity's Last ExamClaude Opus 5.5 by 10.361.451.1+10.3
Other results18 tests, not counted
Tests outside the eight areas. They are not counted above: several are summary scores built from other tests, or the same test under another name.
- Program BenchClaude Opus 5.5 by 59.791.231.5+59.7
- Terminal-Bench-Science 0.1Claude Opus 5.5 by 20.658.738.1+20.6
- PostTrainBenchClaude Opus 5.5 by 12.849.336.5+12.8
- AA IntelligenceClaude Opus 5.5 by 11.657.646+11.6
- PostTrain Bench v1.2Claude Opus 5.5 by 7.343.836.5+7.3
- SWE Marathon v1.1Kimi K3.1 Pro by 5.446.351.7+5.4
- BenchCAD w/ toolsClaude Opus 5.5 by 3.596.292.7+3.5
- baby_vision_with_pythonClaude Opus 5.5 by 2.397.795.4+2.3
- HLE (with tools)Kimi K3.1 Pro by 2.367.770+2.3
- OSWorld 2.1Claude Opus 5.5 by 2.281.879.6+2.2
- ZeroBench_main w/ python (pass@5)Kimi K3.1 Pro by 26163+2
- DeepSWE 1.1Kimi K3.1 Pro by 1.374.275.5+1.3
- ChartoGraphy w/ pythonKimi K3.1 Pro by 1.28990.2+1.2
- Terminal-Bench 4.0tie66.465.7tie
- charxiv_rq_with_pythontie93.893.4tie
- OfficeQA Protie67.767.4tie
- BenchCAD w/o toolstie7372.8tie
- mmmu_pro_with_pythontie89.890tie
Questions people ask
Which is better, Claude Opus 5.5 or Kimi K3.1 Pro?
Claude Opus 5.5 and Kimi K3.1 Pro each win two of the four areas where both have results. Claude Opus 5.5 wins coding and reasoning; Kimi K3.1 Pro wins agents and images and charts. Kimi K3.1 Pro costs 50% less.
Which is better for coding?
Claude Opus 5.5. It wins the one coding test both models report.
Which is cheaper?
Claude Opus 5.5 costs $4.00 per million input tokens and $20.00 per million output tokens; Kimi K3.1 Pro costs $2.00 and $10.00. That makes Kimi K3.1 Pro about 50% cheaper for the same work.
How do you compare the two?
We use the 22 benchmark tests both models have published scores on. The verdict counts the 4 tests in the eight capability areas, and a gap under one point (ten on rating-style scales) counts as a tie. The other 18 are listed but not counted, because several are summary scores or repeat a test. Each score is the one shown on the model's own page.