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Claude Sonnet 4.5 vs Kimi K3

Kimi K3 leads Claude Sonnet 4.5 on coding, 62.3 to 39.5 on the Vibe Coding Index, at about the same output price ($15.00 vs $15.00 per million). Updated October 21, 2026; 73 benchmarks have a result for both.

Replace Claude Sonnet 4.5 Replace Kimi K3
Claude Sonnet 4.5Anthropic
Coding
39.5
Overall
49.5
Output $/M
$15.00
0
Kimi K3Moonshot AI
Coding
62.3
Overall
66.5
Output $/M
$15.00
73
vs boards won of 73 shared

Claude Sonnet 4.5 or Kimi K3: which to pick

Pick Kimi K3 for coding: it scores 62.3 on the Vibe Coding Index against 39.5 for Claude Sonnet 4.5.

Claude Sonnet 4.5 is neither cheaper nor larger in context, and leads no benchmark both models were measured on.

Model AClaude Sonnet 4.5Anthropic39.5/1003 independent benchmarks$1.16 per solved taskModel BKimi K3Moonshot AI62.3/1006 independent benchmarks$0.81 per solved task
Shared results
73
Claude Sonnet 4.5 only
22
Kimi K3 only
44
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 K3 62.3 from 6 benchmarks.
Widest category
Math, 31.2 points apart on average over 6 shared benchmarks.
Widest single gap
ProofBench: Claude Sonnet 4.5 19.0% against Kimi K3 87.0%, 68.0 points apart on a 0 to 100 scale.
Output price
Both cost $15.00 per million output tokens.
Context window
Claude Sonnet 4.5 takes 1M tokens, Kimi K3 1.05M.

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 K3Ties
Coding010
Intelligence02
Agentic work05
Reasoning011
Math06
Knowledge011
Web design07
General021
All shared boards073
CodingLike-for-likeSix of these boards feed the Vibe Coding Index010
Coding benchmarks for Claude Sonnet 4.5 and Kimi K3
BenchmarkClaude Sonnet 4.5Kimi K3Leader
SWE-bench Verified74.8%Not measuredOnly Claude Sonnet 4.5 measured
SWE-bench Multilingual67.0%Not measuredOnly Claude Sonnet 4.5 measured
LiveBench codingNot measured59.3%Only Kimi K3 measured
LMArena WebDev13941655Kimi K3
AA Coding Index52.176.2Kimi K3
LiveCodeBench (Vals AI)73.0%87.2%Kimi K3
SWE-bench Verified (Vals AI)70.0%93.4%Kimi K3
Terminal-Bench 4 (Vals AI)Not measured17.2%Only Kimi K3 measured
Vibe Code Bench (Vals AI)22.6%85.0%Kimi K3
Code migration (Vals AI)Not measured16.1%Only Kimi K3 measured
ProgramBench (Vals AI)Not measured2.0%Only Kimi K3 measured
IOI (Vals AI)Not measured48.9%Only Kimi K3 measured
Terminal-Bench 2.1 (Vals AI)Not measured80.9%Only Kimi K3 measured
SWE-bench Multimodal (Vals AI)Not measured44.2%Only Kimi K3 measured
Vibe Code Bench 1-100 (Vals AI)Not measured18.2%Only Kimi K3 measured
CyberBench (Vals AI)Not measured75.2%Only Kimi K3 measured
SciCodeNot measured59.5%Only Kimi K3 measured
Terminal-Bench46.5%Not measuredOnly Claude Sonnet 4.5 measured
FrontierCodeNot measured44.2%Only Kimi K3 measured
FrontierSWENot measured25.9%Only Kimi K3 measured
GSO-Bench14.7%Not measuredOnly Claude Sonnet 4.5 measured
WeirdML47.7%82.6%Kimi K3
Cybench60.0%Not measuredOnly Claude Sonnet 4.5 measured
ALE-BenchNot measured1524.5Only Kimi K3 measured
LMArena Text: coding14881508Kimi K3
LMArena Text: software and IT14731499Kimi K3
LMArena WebDev: React13861670Kimi K3
LMArena WebDev: HTML13991644Kimi K3
LMArena WebDev: from an imageNot measured1579Only Kimi K3 measured
Neither model has a result on the other 10 boards here
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index02
Intelligence benchmarks for Claude Sonnet 4.5 and Kimi K3
BenchmarkClaude Sonnet 4.5Kimi K3Leader
AA Intelligence Index20.743.6Kimi K3
Epoch Capabilities Index146.7157.9Kimi K3
Agentic workLike-for-likePublic boards, shown as published, kept out of the index05
Agentic work benchmarks for Claude Sonnet 4.5 and Kimi K3
BenchmarkClaude Sonnet 4.5Kimi K3Leader
AA Agentic Index15.850.0Kimi K3
Design Arena: agents building web apps10591295Kimi K3
Design Arena: agents building full-stack apps10501315Kimi K3
Design Arena: agents building mobile apps11371269Kimi K3
Design Arena: agents building Android appsNot measured1250Only Kimi K3 measured
Design Arena: agents building Godot gamesNot measured1223Only Kimi K3 measured
Design Arena: agents building gamesNot measured1252Only Kimi K3 measured
Design Arena: HTML slidesNot measured1256Only Kimi K3 measured
Design Arena: PowerPoint slidesNot measured1273Only Kimi K3 measured
Design Arena: spreadsheetsNot measured1058Only Kimi K3 measured
LiveBench researchNot measured79.0%Only Kimi K3 measured
LiveBench browserNot measured16.0%Only Kimi K3 measured
LiveBench long agenticNot measured42.8%Only Kimi K3 measured
Finance Agent (Vals AI)Not measured53.1%Only Kimi K3 measured
Tax Agent Bench (Vals AI)Not measured33.4%Only Kimi K3 measured
Legal Research Bench (Vals AI)Not measured46.1%Only Kimi K3 measured
Harvey's Legal Agent Benchmark (Vals AI)Not measured12.9%Only Kimi K3 measured
Excel Modeling Benchmark (Vals AI)Not measured66.7%Only Kimi K3 measured
BioMysteryBench (Vals AI)Not measured72.6%Only Kimi K3 measured
Terminal-Bench-Science (Vals AI)Not measured1.4%Only Kimi K3 measured
Time Horizon Index (Vals AI)Not measured10.5%Only Kimi K3 measured
APEX-AgentsNot measured47.8%Only Kimi K3 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
PostTrainBenchNot measured32.0%Only Kimi K3 measured
OSWorld62.9%Not measuredOnly Claude Sonnet 4.5 measured
Vending-Bench 2$3,839$5,165Kimi K3
Berkeley Function Calling Leaderboard (BFCL)73.2%Not measuredOnly Claude Sonnet 4.5 measured
Neither model has a result on the other 11 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index011
Reasoning benchmarks for Claude Sonnet 4.5 and Kimi K3
BenchmarkClaude Sonnet 4.5Kimi K3Leader
GPQA Diamond81.6%92.9%Kimi K3
LiveBench reasoningNot measured90.7%Only Kimi K3 measured
MMMU Pro (Vals AI)79.3%88.2%Kimi K3
GPQA Diamond (Artificial Analysis run)Not measured93.5%Only Kimi K3 measured
Humanity's Last Exam (Artificial Analysis run)Not measured46.9%Only Kimi K3 measured
GPQA Diamond (Epoch AI run)82.3%93.1%Kimi K3
ARC-AGI63.7%94.5%Kimi K3
ARC-AGI-213.6%60.4%Kimi K3
SimpleBench54.3%60.7%Kimi K3
Chess puzzles10.0%37.0%Kimi K3
Mystery game puzzles17.0%26.0%Kimi K3
EBR-bench2.4%Not measuredOnly Claude Sonnet 4.5 measured
VPCT39.8%Not measuredOnly Claude Sonnet 4.5 measured
LMArena Text: hard prompts14621495Kimi K3
LMArena Text: expert14831520Kimi K3
LMArena Text: hard prompts in English14711496Kimi K3
Kagi LLM Benchmark57.9%Not measuredOnly Claude Sonnet 4.5 measured
Neither model has a result on the other 5 boards here
MathLike-for-likePublic boards, shown as published, kept out of the index06
Math benchmarks for Claude Sonnet 4.5 and Kimi K3
BenchmarkClaude Sonnet 4.5Kimi K3Leader
AIME88.2%Not measuredOnly Claude Sonnet 4.5 measured
MGSM (Vals AI)94.3%Not measuredOnly Claude Sonnet 4.5 measured
OTIS Mock AIME77.8%97.2%Kimi K3
FrontierMath, tiers 1 to 323.9%72.2%Kimi K3
FrontierMath, tier 42.4%39.0%Kimi K3
ProofBench19.0%87.0%Kimi K3
MATH level 597.7%Not measuredOnly Claude Sonnet 4.5 measured
LMArena Text: math14491494Kimi K3
LMArena Text: mathematical work14621505Kimi K3
Neither model has a result on the other 4 boards here
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index011
Knowledge benchmarks for Claude Sonnet 4.5 and Kimi K3
BenchmarkClaude Sonnet 4.5Kimi K3Leader
MMLU Pro87.4%88.0%Kimi K3
LegalBench (Vals AI)84.1%86.2%Kimi K3
CaseLaw (Vals AI)62.2%Not measuredOnly Claude Sonnet 4.5 measured
CorpFin (Vals AI)62.0%71.6%Kimi K3
TaxEval (Vals AI)73.3%75.7%Kimi K3
MortgageTax (Vals AI)64.0%66.3%Kimi K3
MedQA (Vals AI)94.7%Not measuredOnly Claude Sonnet 4.5 measured
MedCode (Vals AI)44.1%49.4%Kimi K3
SimpleQA Verified30.7%50.6%Kimi K3
LMArena Text: science14481508Kimi K3
LMArena Text: medicine and healthcare14441489Kimi K3
LMArena Text: legal and government14511503Kimi K3
LMArena Text: business and finance14401470Kimi K3
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 index07
Web design benchmarks for Claude Sonnet 4.5 and Kimi K3
BenchmarkClaude Sonnet 4.5Kimi K3Leader
Design Arena: websites11901335Kimi K3
Design Arena: UI components11731344Kimi K3
Design Arena: game dev11661359Kimi K3
Design Arena: data viz11671351Kimi K3
Design Arena: 3D11581388Kimi K3
Design Arena: all code categories11831360Kimi K3
Design Arena: SVG11151302Kimi K3
Design Arena: ASCII art1205Not measuredOnly Claude Sonnet 4.5 measured
LiveBench designNot measured77.2%Only Kimi K3 measured
GeneralLike-for-likePublic boards, shown as published, kept out of the index021
General benchmarks for Claude Sonnet 4.5 and Kimi K3
BenchmarkClaude Sonnet 4.5Kimi K3Leader
Vals IndexNot measured53.0%Only Kimi K3 measured
LiveBench data analysisNot measured78.7%Only Kimi K3 measured
Public Benefits Bench (Vals AI)Not measured68.2%Only Kimi K3 measured
SAGE (Vals AI)36.1%52.8%Kimi K3
MedScribe (Vals AI)84.5%88.0%Kimi K3
Vals Multimodal IndexNot measured73.4%Only Kimi K3 measured
Long context reasoning (AA-LCR)Not measured88.7%Only Kimi K3 measured
DTBench83.2%91.2%Kimi K3
LMCA38.8%52.7%Kimi K3
Surface Evolver BenchNot measured95.0%Only Kimi K3 measured
Furniture assemblyNot measured34.2%Only Kimi K3 measured
LMArena Text14381476Kimi K3
LMArena Text: instruction following14591485Kimi K3
LMArena Text: creative writing14421457Kimi K3
LMArena Text: English14501481Kimi K3
LMArena Text: non-English14251466Kimi K3
LMArena Text: Chinese14601529Kimi K3
LMArena Text: German14271490Kimi K3
LMArena Text: Japanese13901494Kimi K3
LMArena Text: Korean14021460Kimi K3
LMArena Text: French14591492Kimi K3
LMArena Text: Spanish14581472Kimi K3
LMArena Text: Russian14371485Kimi K3
LMArena Text: Polish14231458Kimi K3
LMArena Text: multi-turn14651489Kimi K3
LMArena Text: longer queries14751494Kimi K3
LMArena Text: writing and language14421471Kimi K3
LMArena Text: entertainment and media14281453Kimi K3
LMArena Document1450Not measuredOnly Claude Sonnet 4.5 measured
Neither model has a result on the other 17 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 K3
BenchmarkClaude Sonnet 4.5Kimi K3Leader
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 K3$0.011Fits in one request

Same cost

Repository review

50K input + 3K output tokens

Claude Sonnet 4.5$0.195Fits in one request
Kimi K3$0.195Fits in one request

Same cost

Agent loop

200K input + 10K output tokens

Claude Sonnet 4.5$0.750Fits in one request
Kimi K3$0.750Fits in one request

Same cost

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 K3
SpecificationAnthropic Claude Sonnet 4.5MoonshotAI Kimi K3
MakerAnthropicMoonshot AI
WeightsNo public weights listedOpen weights
ReleasedSeptember 29, 2025July 16, 2026
Context window1M1.05M
Input $/Mtok$3.00$3.00
Output $/Mtok$15.00$15.00
Coding index39.562.3
Independent measurements behind it36
Cost per solved task$1.16$0.81
SourceOpenRouter listingOpenRouter listing

Questions

Is Claude Sonnet 4.5 better than Kimi K3 for coding?

Pick Kimi K3 for coding: it scores 62.3 on the Vibe Coding Index against 39.5 for Claude Sonnet 4.5. Claude Sonnet 4.5 is neither cheaper nor larger in context, and leads no benchmark both models were measured on.

Which is cheaper, Claude Sonnet 4.5 or Kimi K3?

Claude Sonnet 4.5 costs $3.00 per million input tokens and $15.00 per million output tokens; Kimi K3 costs $3.00 and $15.00. Per solved SWE-bench Verified task, Claude Sonnet 4.5 costs $1.16 and Kimi K3 $0.81.

Which has the bigger context window, Claude Sonnet 4.5 or Kimi K3?

Kimi K3, with 1.05M tokens against 1M.

How many benchmarks is the Claude Sonnet 4.5 vs Kimi K3 comparison based on?

73 benchmarks have a result for both models as of October 21, 2026. Claude Sonnet 4.5's coding index rests on 3 independent benchmarks and Kimi K3's on 6. Where only one model has a result, the page says so instead of naming a winner.

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