Claude Opus 5.5 vs Kimi K2.6
Wins 8 of 8 areas
Coding · Agents · Reasoning · Facts · Images and charts · Math · Long documents · Following instructions
Wins 0 of 8 areas
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Claude Opus 5.5 is the stronger all-rounder.Kimi K2.6 is cheaper.
Scores updated · 33 tests both models report · How we compare
Where each one wins
Tests won in each of the eight areas we test. Each piece is one test, so a longer bar means more evidence; grey means the two scored within a point of each other.
- CodingWriting and fixing software60Claude Opus 5.56 of 6 tests
- AgentsCarrying out multi-step tasks on its own30Claude Opus 5.53 of 3 tests
- ReasoningHard problems that need careful thinking30Claude Opus 5.53 of 3 tests
- MathCompetition and research-level math30Claude Opus 5.53 of 3 tests
- Images and chartsUnderstanding pictures, charts and video20Claude Opus 5.52 of 2 tests
- FactsGetting facts right instead of making them up21Claude Opus 5.52 of 4 tests · 1 tie
- Long documentsFinding answers in very long texts10Claude Opus 5.51 of 1 test
- Following instructionsDoing exactly what it is asked10Claude Opus 5.51 of 1 test
Long documents and following instructions 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 K2.6 costs 79% 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
- Extremely hard research-level math problemsFrontierMath Tier 4+69.4points ahead
- Complex command-line tasks across many fieldsTerminal-Bench 4.0+59.1points ahead
- Real work tasks from 44 professionsGDPVal+41.4points ahead
Where Kimi K2.6 pulls ahead
- Avoids making up answers it doesn't knowAA-Omniscience · Non-hallucination+18.1points ahead
Every test, side by side
All 33 tests both models report. The winning score is in its model's colour; marks a score checked independently.
CodingClaude Opus 5.5
- SWE-bench ProClaude Opus 5.5 by 31.389.958.6+31.3
- LMArena · WebDevClaude Opus 5.5 by 300 rating points18091509+300 rating
- LiveBench · Agentic CodingClaude Opus 5.5 by 24.871.746.9+24.8
- SWE-bench MultilingualClaude Opus 5.5 by 17.293.976.7+17.2
- SciCodeClaude Opus 5.5 by 15.466.951.5+15.4
- LiveBench · CodingClaude Opus 5.5 by 10.789.378.6+10.7
AgentsClaude Opus 5.5
- Terminal-Bench 4.0Claude Opus 5.5 by 59.159.60.5+59.1
- GDPValClaude Opus 5.5 by 41.468.326.9+41.4
- AA IT-Bench SREClaude Opus 5.5 by 738.231.2+7
ReasoningClaude Opus 5.5
- Humanity's Last ExamClaude Opus 5.5 by 23.961.437.5+23.9
- CritPtClaude Opus 5.5 by 23.731.78+23.7
- LiveBench · ReasoningClaude Opus 5.5 by 12.892.279.4+12.8
FactsClaude Opus 5.5
- SimpleQA VerifiedClaude Opus 5.5 by 37.372.234.9+37.3
- AA-Omniscience · AccuracyClaude Opus 5.5 by 33.666.232.6+33.6
- AA-Omniscience · Non-hallucinationKimi K2.6 by 18.141.459.5+18.1
- Vectara HHEM hallucination ratelower is bettertie9.910.8tie
Images and chartsClaude Opus 5.5
- MMMU-ProClaude Opus 5.5 by 8.387.779.4+8.3
- LMArena · VisionClaude Opus 5.5 by 39 rating points13211282+39 rating
MathClaude Opus 5.5
- FrontierMath Tier 4Claude Opus 5.5 by 69.49525.6+69.4
- FrontierMath Tiers 1-3 (v2)Claude Opus 5.5 by 3491.257.2+34
- LiveBench · MathematicsClaude Opus 5.5 by 12.897.184.3+12.8
Following instructionsClaude Opus 5.5
- LiveBench · Instruction FollowingClaude Opus 5.5 by 1.365.764.4+1.3
Other results10 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.
- AA-OmniscienceClaude Opus 5.5 by 41.146.45.3+41.1
- HiL-Bench (Tools-allowed)Claude Opus 5.5 by 40.35918.7+40.3
- GDPval-AA (Elo)Claude Opus 5.5 by 338 rating points18201482+338 rating
- AA IntelligenceClaude Opus 5.5 by 30.657.627+30.6
- livebench_data_analysisClaude Opus 5.5 by 15.280.365.1+15.2
- HLE (with tools)Claude Opus 5.5 by 13.767.754+13.7
- livebench_languageClaude Opus 5.5 by 11.286.375.1+11.2
- vectara_avg_summary_lengthClaude Opus 5.5 by 75.4 rating points192.1116.7+75.4 rating
- vectara_factual_consistencytie90.189.2tie
- vectara_answer_ratetie99.799.7tie
Questions people ask
Which is better, Claude Opus 5.5 or Kimi K2.6?
Claude Opus 5.5 wins all eight areas we test: coding, agents, reasoning, facts, images and charts, math, long documents and following instructions. Kimi K2.6 wins none, but costs 79% less.
Which is better for coding?
Claude Opus 5.5. It wins 6 of the 6 coding tests both models report; Kimi K2.6 wins none.
Which is cheaper?
Claude Opus 5.5 costs $4.00 per million input tokens and $20.00 per million output tokens; Kimi K2.6 costs $0.95 and $4.00. That makes Kimi K2.6 about 79% cheaper for the same work.
How do you compare the two?
We use the 33 benchmark tests both models have published scores on. The verdict counts the 23 tests in the eight capability areas, and a gap under one point (ten on rating-style scales) counts as a tie. The other 10 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.