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Claude Sonnet 4.5 vs Kimi K2.5

Claude Sonnet 4.5 leads Kimi K2.5 on coding, 39.5 to 38.6 on the Vibe Coding Index, and Kimi K2.5 costs 5.3x less per output token ($2.85 vs $15.00 per million). Updated October 22, 2026; 71 benchmarks have a result for both.

Replace Claude Sonnet 4.5 Replace Kimi K2.5
Claude Sonnet 4.5Anthropic
Coding
39.5
Overall
49.5
Output $/M
$15.00
30
Kimi K2.5Moonshot AI
Coding
38.6
Overall
44.8
Output $/M
$2.85
40
vs boards won of 71 shared, 1 tied

Claude Sonnet 4.5 or Kimi K2.5: which to pick

Claude Sonnet 4.5 and Kimi K2.5 are level for coding, 39.5 against 38.6 on the Vibe Coding Index, so price and context decide.

Pick Kimi K2.5 for output tokens 5.3x cheaper ($2.85 vs $15.00 per million) and a lower cost per solved task ($0.24 against $1.16). Pick Claude Sonnet 4.5 for a larger context window (1M against 262K tokens) and work measured by SWE-bench Verified or AA Coding Index, where it leads.

Model AClaude Sonnet 4.5Anthropic39.5/1003 independent benchmarks$1.16 per solved taskModel BKimi K2.5Moonshot AI38.6/1003 independent benchmarks$0.24 per solved task
Shared results
71
Claude Sonnet 4.5 only
24
Kimi K2.5 only
28
Like-for-like categories
8 of 9

Only benchmarks that tested both models count toward a pick; a result only one model has is shown but not compared.

Which one for your work

Each card is decided by one number both models carry. Where only one has it, the card says so and makes no call.

At a glance

Coding index
Claude Sonnet 4.5 39.5 from 3 benchmarks, Kimi K2.5 38.6 from 3 benchmarks.
Widest category
Agentic work, 7.1 points apart on average over 5 shared benchmarks.
Widest single gap
Kagi LLM Benchmark: Claude Sonnet 4.5 57.9% against Kimi K2.5 78.5%, 20.6 points apart on a 0 to 100 scale.
Output price
Claude Sonnet 4.5 $15.00 against Kimi K2.5 $2.85 per million output tokens, 5.3x apart.
Context window
Claude Sonnet 4.5 takes 1M tokens, Kimi K2.5 262K.

Benchmark by benchmark

First the score: boards each model leads, per category, where both have a result. Then every board, a category to a fold; bars are each result on a 0 to 100 scale, so compare the two in a row, not one row with another.

Boards won, where both have a result
CategoryClaude Sonnet 4.5BarsKimi K2.5Ties
Coding751 tie
Intelligence02
Agentic work14
Reasoning54
Math03
Knowledge66
Web design17
General109
All shared boards30401 tie
CodingLike-for-likeSix of these boards feed the Vibe Coding Index75
Coding benchmarks for Claude Sonnet 4.5 and Kimi K2.5
BenchmarkClaude Sonnet 4.5Kimi K2.5Leader
SWE-bench Verified74.8%70.8%Claude Sonnet 4.5
SWE-bench Multilingual67.0%67.3%Kimi K2.5
LMArena WebDev13941437Kimi K2.5
AA Coding Index52.146.8Claude Sonnet 4.5
LiveCodeBench (Vals AI)73.0%83.9%Kimi K2.5
SWE-bench Verified (Vals AI)70.0%70.0%Tie
Vibe Code Bench (Vals AI)22.6%17.5%Claude Sonnet 4.5
Code migration (Vals AI)Not measured7.0%Only Kimi K2.5 measured
Terminal-Bench 2.1 (Vals AI)Not measured42.0%Only Kimi K2.5 measured
Terminal-Bench Hard (Artificial Analysis run)Not measured34.8%Only Kimi K2.5 measured
Terminal-Bench46.5%43.2%Claude Sonnet 4.5
GSO-Bench14.7%Not measuredOnly Claude Sonnet 4.5 measured
WeirdML47.7%45.6%Claude Sonnet 4.5
Cybench60.0%Not measuredOnly Claude Sonnet 4.5 measured
ALE-BenchNot measured821.6Only Kimi K2.5 measured
LMArena Text: coding14881483Claude Sonnet 4.5
LMArena Text: software and IT14731471Claude Sonnet 4.5
LMArena WebDev: React13861429Kimi K2.5
LMArena WebDev: HTML13991426Kimi K2.5
LMArena WebDev: from an imageNot measured1439Only Kimi K2.5 measured
Neither model has a result on the other 19 boards here
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index02
Intelligence benchmarks for Claude Sonnet 4.5 and Kimi K2.5
BenchmarkClaude Sonnet 4.5Kimi K2.5Leader
AA Intelligence Index20.723.5Kimi K2.5
Epoch Capabilities Index146.7148.1Kimi K2.5
Agentic workLike-for-likePublic boards, shown as published, kept out of the index14
Agentic work benchmarks for Claude Sonnet 4.5 and Kimi K2.5
BenchmarkClaude Sonnet 4.5Kimi K2.5Leader
AA Agentic Index15.8Not measuredOnly Claude Sonnet 4.5 measured
Design Arena: agents building web apps10601136Kimi K2.5
Design Arena: agents building full-stack apps10501114Kimi K2.5
Design Arena: agents building mobile apps11371147Kimi K2.5
Design Arena: agents building Android appsNot measured1118Only Kimi K2.5 measured
Design Arena: agents building Godot gamesNot measured1219Only Kimi K2.5 measured
Finance Agent (Vals AI)Not measured35.8%Only Kimi K2.5 measured
Legal Research Bench (Vals AI)Not measured15.9%Only Kimi K2.5 measured
Excel Modeling Benchmark (Vals AI)Not measured28.5%Only Kimi K2.5 measured
τ²-Bench TelecomNot measured95.9%Only Kimi K2.5 measured
METR time horizons67.4%Not measuredOnly Claude Sonnet 4.5 measured
Remote Labor Index2.1%Not measuredOnly Claude Sonnet 4.5 measured
GDPval42.5%Not measuredOnly Claude Sonnet 4.5 measured
DeepResearch Bench52.6%Not measuredOnly Claude Sonnet 4.5 measured
OSWorld62.9%63.3%Kimi K2.5
Vending-Bench 2$3,839$1,198Claude Sonnet 4.5
Berkeley Function Calling Leaderboard (BFCL)73.2%Not measuredOnly Claude Sonnet 4.5 measured
Neither model has a result on the other 24 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index54
Reasoning benchmarks for Claude Sonnet 4.5 and Kimi K2.5
BenchmarkClaude Sonnet 4.5Kimi K2.5Leader
GPQA Diamond81.6%84.1%Kimi K2.5
MMMU Pro (Vals AI)79.3%84.3%Kimi K2.5
GPQA Diamond (Artificial Analysis run)Not measured87.9%Only Kimi K2.5 measured
Humanity's Last Exam (Artificial Analysis run)Not measured30.7%Only Kimi K2.5 measured
GPQA Diamond (Epoch AI run)82.3%Not measuredOnly Claude Sonnet 4.5 measured
ARC-AGI63.7%65.3%Kimi K2.5
ARC-AGI-213.6%11.8%Claude Sonnet 4.5
SimpleBench54.3%46.8%Claude Sonnet 4.5
Chess puzzles10.0%Not measuredOnly Claude Sonnet 4.5 measured
Mystery game puzzles17.0%Not measuredOnly Claude Sonnet 4.5 measured
EBR-bench2.4%Not measuredOnly Claude Sonnet 4.5 measured
VPCT39.8%Not measuredOnly Claude Sonnet 4.5 measured
LMArena Text: hard prompts14621453Claude Sonnet 4.5
LMArena Text: expert14831466Claude Sonnet 4.5
LMArena Text: hard prompts in English14711460Claude Sonnet 4.5
LMArena Vision: diagramsNot measured1282Only Kimi K2.5 measured
LMArena Vision: homeworkNot measured1297Only Kimi K2.5 measured
Kagi LLM Benchmark57.9%78.5%Kimi K2.5
Neither model has a result on the other 4 boards here
MathLike-for-likePublic boards, shown as published, kept out of the index03
Math benchmarks for Claude Sonnet 4.5 and Kimi K2.5
BenchmarkClaude Sonnet 4.5Kimi K2.5Leader
AIME88.2%95.6%Kimi K2.5
MGSM (Vals AI)94.3%Not measuredOnly Claude Sonnet 4.5 measured
OTIS Mock AIME77.8%Not measuredOnly Claude Sonnet 4.5 measured
FrontierMath, tiers 1 to 323.9%Not measuredOnly Claude Sonnet 4.5 measured
FrontierMath, tier 42.4%Not measuredOnly Claude Sonnet 4.5 measured
ProofBench19.0%Not measuredOnly Claude Sonnet 4.5 measured
MATH level 597.7%Not measuredOnly Claude Sonnet 4.5 measured
LMArena Text: math14491470Kimi K2.5
LMArena Text: mathematical work14621473Kimi K2.5
Neither model has a result on the other 4 boards here
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index66
Knowledge benchmarks for Claude Sonnet 4.5 and Kimi K2.5
BenchmarkClaude Sonnet 4.5Kimi K2.5Leader
MMLU Pro87.4%85.9%Claude Sonnet 4.5
LegalBench (Vals AI)84.1%Not measuredOnly Claude Sonnet 4.5 measured
CaseLaw (Vals AI)62.2%58.7%Claude Sonnet 4.5
CorpFin (Vals AI)62.0%68.3%Kimi K2.5
TaxEval (Vals AI)73.3%74.2%Kimi K2.5
MortgageTax (Vals AI)64.0%66.5%Kimi K2.5
MedQA (Vals AI)94.7%94.4%Claude Sonnet 4.5
MedCode (Vals AI)44.1%39.3%Claude Sonnet 4.5
SimpleQA Verified30.7%34.3%Kimi K2.5
LMArena Text: science14481459Kimi K2.5
LMArena Text: medicine and healthcare14441448Kimi K2.5
LMArena Text: legal and government14511441Claude Sonnet 4.5
LMArena Text: business and finance14401427Claude Sonnet 4.5
FACTS Benchmark Suite40.6%Not measuredOnly Claude Sonnet 4.5 measured
Neither model has a result on the other 4 boards here
Web designLike-for-likePublic boards, shown as published, kept out of the index17
Web design benchmarks for Claude Sonnet 4.5 and Kimi K2.5
BenchmarkClaude Sonnet 4.5Kimi K2.5Leader
Design Arena: websites11891248Kimi K2.5
Design Arena: UI components11701234Kimi K2.5
Design Arena: game dev11661206Kimi K2.5
Design Arena: data viz11671219Kimi K2.5
Design Arena: 3D11571204Kimi K2.5
Design Arena: all code categories11821236Kimi K2.5
Design Arena: SVG11151149Kimi K2.5
Design Arena: ASCII art12051166Claude Sonnet 4.5
Neither model has a result on the other 1 board here
GeneralLike-for-likePublic boards, shown as published, kept out of the index109
General benchmarks for Claude Sonnet 4.5 and Kimi K2.5
BenchmarkClaude Sonnet 4.5Kimi K2.5Leader
SAGE (Vals AI)36.1%49.9%Kimi K2.5
MedScribe (Vals AI)84.5%76.4%Claude Sonnet 4.5
IFBenchNot measured70.2%Only Kimi K2.5 measured
Long context reasoning (AA-LCR)Not measured78.0%Only Kimi K2.5 measured
DTBench83.2%Not measuredOnly Claude Sonnet 4.5 measured
LMCA38.8%Not measuredOnly Claude Sonnet 4.5 measured
Fiction.LiveBenchNot measured86.1%Only Kimi K2.5 measured
CL-benchNot measured19.3%Only Kimi K2.5 measured
CL-bench LifeNot measured13.2%Only Kimi K2.5 measured
LMArena Text14381445Kimi K2.5
LMArena Text: instruction following14591431Claude Sonnet 4.5
LMArena Text: creative writing14421422Claude Sonnet 4.5
LMArena VisionNot measured1269Only Kimi K2.5 measured
LMArena Text: English14501453Kimi K2.5
LMArena Text: non-English14251433Kimi K2.5
LMArena Text: Chinese14601494Kimi K2.5
LMArena Text: German14271441Kimi K2.5
LMArena Text: Japanese13901423Kimi K2.5
LMArena Text: Korean14021412Kimi K2.5
LMArena Text: French14591454Claude Sonnet 4.5
LMArena Text: Spanish14581450Claude Sonnet 4.5
LMArena Text: Russian14371435Claude Sonnet 4.5
LMArena Text: Polish14231445Kimi K2.5
LMArena Text: multi-turn14651444Claude Sonnet 4.5
LMArena Text: longer queries14751445Claude Sonnet 4.5
LMArena Text: writing and language14421425Claude Sonnet 4.5
LMArena Text: entertainment and media14281417Claude Sonnet 4.5
LMArena Vision: EnglishNot measured1274Only Kimi K2.5 measured
LMArena Vision: ChineseNot measured1328Only Kimi K2.5 measured
LMArena Vision: reading textNot measured1276Only Kimi K2.5 measured
LMArena Vision: humorNot measured1284Only Kimi K2.5 measured
LMArena Vision: captioningNot measured1257Only Kimi K2.5 measured
LMArena Vision: recognizing thingsNot measured1285Only Kimi K2.5 measured
LMArena Vision: creative writingNot measured1269Only Kimi K2.5 measured
LMArena Document1450Not measuredOnly Claude Sonnet 4.5 measured
Neither model has a result on the other 11 boards here
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
Image generation benchmarks for Claude Sonnet 4.5 and Kimi K2.5
BenchmarkClaude Sonnet 4.5Kimi K2.5Leader
Neither model has a result on 5 boards here

What each workload costs

Three fixed token mixes at each model's listed price, so per-token rates become a bill.

Chat turn

1K input + 500 output tokens

Claude Sonnet 4.5$0.011Fits in one request
Kimi K2.5$0.0020Fits in one request

Kimi K2.5 costs less

Repository review

50K input + 3K output tokens

Claude Sonnet 4.5$0.195Fits in one request
Kimi K2.5$0.035Fits in one request

Kimi K2.5 costs less

Agent loop

200K input + 10K output tokens

Claude Sonnet 4.5$0.750Fits in one request
Kimi K2.5$0.135Fits in one request

Kimi K2.5 costs less

Listed OpenRouter rates, without cache or batch discounts. A workload that does not fit a model's context window would need splitting.

Specification differences

The leading value in a row is marked; a row with a missing value names no leader. Our two rows are marked in red.

Specifications of Claude Sonnet 4.5 and Kimi K2.5
SpecificationAnthropic Claude Sonnet 4.5MoonshotAI Kimi K2.5
MakerAnthropicMoonshot AI
WeightsNo public weights listedOpen weights
ReleasedSeptember 29, 2025January 27, 2026
Context window1M262K
Input $/Mtok$3.00$0.532
Output $/Mtok$15.00$2.85
Coding index39.538.6
Independent measurements behind it33
Cost per solved task$1.16$0.24
SourceOpenRouter listingOpenRouter listing

Questions

Is Claude Sonnet 4.5 better than Kimi K2.5 for coding?

Claude Sonnet 4.5 and Kimi K2.5 are level for coding, 39.5 against 38.6 on the Vibe Coding Index, so price and context decide. Pick Kimi K2.5 for output tokens 5.3x cheaper ($2.85 vs $15.00 per million) and a lower cost per solved task ($0.24 against $1.16). Pick Claude Sonnet 4.5 for a larger context window (1M against 262K tokens) and work measured by SWE-bench Verified or AA Coding Index, where it leads.

Which is cheaper, Claude Sonnet 4.5 or Kimi K2.5?

Claude Sonnet 4.5 costs $3.00 per million input tokens and $15.00 per million output tokens; Kimi K2.5 costs $0.532 and $2.85. Per solved SWE-bench Verified task, Claude Sonnet 4.5 costs $1.16 and Kimi K2.5 $0.24.

Which has the bigger context window, Claude Sonnet 4.5 or Kimi K2.5?

Claude Sonnet 4.5, with 1M tokens against 262K.

How many benchmarks is the Claude Sonnet 4.5 vs Kimi K2.5 comparison based on?

71 benchmarks have a result for both models as of October 22, 2026. Claude Sonnet 4.5's coding index rests on 3 independent benchmarks and Kimi K2.5's on 3. Where only one model has a result, the page says so instead of naming a winner.

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