Claude Sonnet 4 vs Kimi K2 (Non-Reasoning)
Wins 5 of 6 areas
Coding · Reasoning · Facts · Long documents · Following instructions
Wins 1 of 6 areas
Agents
Claude Sonnet 4 is the stronger all-rounder.Kimi K2 (Non-Reasoning) is cheaper and better at agents.
Scores updated · 20 tests both models report · How we compare
Where each one wins
Tests won in each of the six 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.
- ReasoningHard problems that need careful thinking30Claude Sonnet 43 of 4 tests · 1 tie
- CodingWriting and fixing software20Claude Sonnet 42 of 2 tests
- FactsGetting facts right instead of making them up21Claude Sonnet 42 of 3 tests
- Long documentsFinding answers in very long texts10Claude Sonnet 41 of 1 test
- Following instructionsDoing exactly what it is asked10Claude Sonnet 41 of 1 test
- AgentsCarrying out multi-step tasks on its own01Kimi K2 (Non-Reasoning)1 of 1 test
Agents, 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 (Non-Reasoning) costs 84% 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 Sonnet 4 pulls ahead
- Avoids making up answers it doesn't knowAA-Omniscience · Non-hallucination+47.5points ahead
- Common-sense trick questionsSimpleBench+19.2points ahead
- Reasons across sets of long documentsAA-LCR+17.3points ahead
Where Kimi K2 (Non-Reasoning) pulls ahead
- Real work tasks from 44 professionsGDPVal+14.9points ahead
- Answers hard knowledge questions correctlyAA-Omniscience · Accuracy+4.7points ahead
Every test, side by side
All 20 tests both models report. The winning score is in its model's colour; marks a score checked independently.
CodingClaude Sonnet 4
- Terminal-Bench HardClaude Sonnet 4 by 15.231.115.9+15.2
- SciCodeClaude Sonnet 4 by 5.54034.5+5.5
ReasoningClaude Sonnet 4
- SimpleBenchClaude Sonnet 4 by 19.245.526.3+19.2
- Humanity's Last ExamClaude Sonnet 4 by 3.310.77.4+3.3
- GPQA DiamondClaude Sonnet 4 by 1.177.776.6+1.1
- CritPttie0.30tie
FactsClaude Sonnet 4
- AA-Omniscience · Non-hallucinationClaude Sonnet 4 by 47.570.923.4+47.5
- Vectara HHEM hallucination ratelower is betterClaude Sonnet 4 by 7.610.317.9+7.6
- AA-Omniscience · AccuracyKimi K2 (Non-Reasoning) by 4.722.727.4+4.7
Following instructionsClaude Sonnet 4
- IFBenchClaude Sonnet 4 by 13.254.741.5+13.2
Other results8 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 Agentic IndexKimi K2 (Non-Reasoning) by 30.317.647.9+30.3
- AA-OmniscienceClaude Sonnet 4 by 28.50.2-28.3+28.5
- vectara_avg_summary_lengthClaude Sonnet 4 by 86.6 rating points145.859.2+86.6 rating
- vectara_factual_consistencyClaude Sonnet 4 by 7.689.782.1+7.6
- AA IntelligenceClaude Sonnet 4 by 6.218.912.7+6.2
- τ²-Bench Telecom (AA run)Claude Sonnet 4 by 3.564.661.1+3.5
- Artificial Analysis Coding IndexClaude Sonnet 4 by 2.837.634.8+2.8
- vectara_answer_ratetie98.698.6tie
Questions people ask
Which is better, Claude Sonnet 4 or Kimi K2 (Non-Reasoning)?
Claude Sonnet 4 wins five of the six areas where both have results: coding, reasoning, facts, long documents and following instructions. Kimi K2 (Non-Reasoning) wins agents, and costs 84% less.
Which is better for coding?
Claude Sonnet 4. It wins 2 of the 2 coding tests both models report; Kimi K2 (Non-Reasoning) wins none.
Which is cheaper?
Claude Sonnet 4 costs $3.00 per million input tokens and $15.00 per million output tokens; Kimi K2 (Non-Reasoning) costs $0.57 and $2.30. That makes Kimi K2 (Non-Reasoning) about 84% cheaper for the same work.
How do you compare the two?
We use the 20 benchmark tests both models have published scores on. The verdict counts the 12 tests in the eight capability areas, and a gap under one point (ten on rating-style scales) counts as a tie. The other 8 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.