Claude Sonnet 4.5 vs Kimi K2 Thinking

Kimi K2 Thinking leads Claude Sonnet 4.5 on the Artificial Analysis Intelligence Index, 22.0 to 20.7, and Kimi K2 Thinking costs 6.0x less per output token ($2.50 vs $15.00 per million). Updated October 22, 2026; 18 benchmarks have a result for both.

Replace Claude Sonnet 4.5 Replace Kimi K2 Thinking

Claude Sonnet 4.5Anthropic

Coding: 39.5
Overall: 49.5
Output $/M: $15.00

Kimi K2 ThinkingMoonshot AI

Coding: No data
Overall: No data
Output $/M: $2.50

vs boards won of 18 shared

Claude Sonnet 4.5 or Kimi K2 Thinking: which to pick

Only Claude Sonnet 4.5 has a coding score, 39.5 on the Vibe Coding Index; Kimi K2 Thinking has none, so the two cannot be ranked on coding.

Pick Kimi K2 Thinking for output tokens 6.0x cheaper ($2.50 vs $15.00 per million) and a lower cost per solved task ($0.61 against $1.16).

Model AClaude Sonnet 4.5Anthropic39.5/1003 independent benchmarks$1.16 per solved task Model BKimi K2 ThinkingMoonshot AINot benchmarked1 independent benchmark$0.61 per solved task

187712

Shared results: 18
Claude Sonnet 4.5 only: 77
Kimi K2 Thinking only: 12
Like-for-like categories: 7 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.

Coding
Vibe Coding Index, six public coding benchmarks
No call
Only Claude Sonnet 4.5 has a coding score, so no call is made.
One side not measured
Intelligence
AA Intelligence Index
Kimi K2 Thinking
Kimi K2 Thinking leads, 22.0 against 20.7.
Same board, both measured
Agentic work
AA Agentic Index
No call
Only Claude Sonnet 4.5 has a AA Agentic Index result, 15.8.
Directional only
Reasoning
GPQA Diamond
Claude Sonnet 4.5
Claude Sonnet 4.5 leads, 81.6% against 78.5%.
Same board, both measured
Math
AIME
Claude Sonnet 4.5
Claude Sonnet 4.5 leads, 88.2% against 85.4%.
Same board, both measured
Knowledge
MMLU Pro
Claude Sonnet 4.5
Claude Sonnet 4.5 leads, 87.4% against 81.1%.
Same board, both measured
Web design
Design Arena: websites
Claude Sonnet 4.5
Claude Sonnet 4.5 leads, 1189 against 1113.
Same board, both measured
Long documents
Listed context window
Claude Sonnet 4.5
Claude Sonnet 4.5 takes 1M tokens against 262K.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
Kimi K2 Thinking
Claude Sonnet 4.5 $0.011, Kimi K2 Thinking $0.0019 per turn.
List prices
Cost per solved task
One SWE-bench Verified task, solved
Kimi K2 Thinking
Claude Sonnet 4.5 $1.16, Kimi K2 Thinking $0.61.
Published attempt cost and pass rate

At a glance

Coding index: Claude Sonnet 4.5 39.5 from 3 benchmarks, Kimi K2 Thinking not benchmarked.
Widest category: Web design, 9.5 points apart on average over 1 shared benchmark.
Widest single gap: SWE-bench Verified: Claude Sonnet 4.5 74.8% against Kimi K2 Thinking 63.4%, 11.4 points apart on a 0 to 100 scale.
Output price: Claude Sonnet 4.5 $15.00 against Kimi K2 Thinking $2.50 per million output tokens, 6.0x apart.
Context window: Claude Sonnet 4.5 takes 1M tokens, Kimi K2 Thinking 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
Category	Claude Sonnet 4.5	Kimi K2 Thinking
Coding	5	0
Intelligence	1	1
Agentic work	1	0
Reasoning	1	0
Math	2	0
Knowledge	5	1
Web design	1	0
All shared boards	16	2

CodingLike-for-likeSix of these boards feed the Vibe Coding Index50

Coding benchmarks for Claude Sonnet 4.5 and Kimi K2 Thinking
Benchmark	Claude Sonnet 4.5	Kimi K2 Thinking	Leader
SWE-bench Verified	74.8%	63.4%	Claude Sonnet 4.5
SWE-bench Multilingual	67.0%	Not measured	Only Claude Sonnet 4.5 measured
LMArena WebDev	1394	Not measured	Only Claude Sonnet 4.5 measured
AA Coding Index	52.1	Not measured	Only Claude Sonnet 4.5 measured
LiveCodeBench (Vals AI)	73.0%	63.1%	Claude Sonnet 4.5
SWE-bench Verified (Vals AI)	70.0%	60.2%	Claude Sonnet 4.5
Vibe Code Bench (Vals AI)	22.6%	Not measured	Only Claude Sonnet 4.5 measured
LiveCodeBench (Artificial Analysis run)	Not measured	85.3%	Only Kimi K2 Thinking measured
Terminal-Bench Hard (Artificial Analysis run)	Not measured	31.1%	Only Kimi K2 Thinking measured
Terminal-Bench	46.5%	35.7%	Claude Sonnet 4.5
GSO-Bench	14.7%	Not measured	Only Claude Sonnet 4.5 measured
WeirdML	47.7%	42.8%	Claude Sonnet 4.5
Cybench	60.0%	Not measured	Only Claude Sonnet 4.5 measured
ALE-Bench	Not measured	597.5	Only Kimi K2 Thinking measured
LMArena Text: coding	1488	Not measured	Only Claude Sonnet 4.5 measured
LMArena Text: software and IT	1473	Not measured	Only Claude Sonnet 4.5 measured
LMArena WebDev: React	1386	Not measured	Only Claude Sonnet 4.5 measured
LMArena WebDev: HTML	1399	Not measured	Only Claude Sonnet 4.5 measured
Neither model has a result on the other 21 boards here

IntelligenceLike-for-likePublic boards, shown as published, kept out of the index11

Intelligence benchmarks for Claude Sonnet 4.5 and Kimi K2 Thinking
Benchmark	Claude Sonnet 4.5	Kimi K2 Thinking	Leader
AA Intelligence Index	20.7	22.0	Kimi K2 Thinking
Epoch Capabilities Index	146.7	145.8	Claude Sonnet 4.5

Agentic workLike-for-likePublic boards, shown as published, kept out of the index10

Agentic work benchmarks for Claude Sonnet 4.5 and Kimi K2 Thinking
Benchmark	Claude Sonnet 4.5	Kimi K2 Thinking	Leader
AA Agentic Index	15.8	Not measured	Only Claude Sonnet 4.5 measured
Design Arena: agents building web apps	1060	Not measured	Only Claude Sonnet 4.5 measured
Design Arena: agents building full-stack apps	1050	Not measured	Only Claude Sonnet 4.5 measured
Design Arena: agents building mobile apps	1137	Not measured	Only Claude Sonnet 4.5 measured
τ²-Bench Telecom	Not measured	93.0%	Only Kimi K2 Thinking measured
METR time horizons	67.4%	59.2%	Claude Sonnet 4.5
Remote Labor Index	2.1%	Not measured	Only Claude Sonnet 4.5 measured
GDPval	42.5%	Not measured	Only Claude Sonnet 4.5 measured
DeepResearch Bench	52.6%	Not measured	Only Claude Sonnet 4.5 measured
OSWorld	62.9%	Not measured	Only Claude Sonnet 4.5 measured
Vending-Bench 2	$3,839	Not measured	Only Claude Sonnet 4.5 measured
Berkeley Function Calling Leaderboard (BFCL)	73.2%	Not measured	Only Claude Sonnet 4.5 measured
Neither model has a result on the other 29 boards here

ReasoningLike-for-likePublic boards, shown as published, kept out of the index10

Reasoning benchmarks for Claude Sonnet 4.5 and Kimi K2 Thinking
Benchmark	Claude Sonnet 4.5	Kimi K2 Thinking	Leader
GPQA Diamond	81.6%	78.5%	Claude Sonnet 4.5
MMMU Pro (Vals AI)	79.3%	Not measured	Only Claude Sonnet 4.5 measured
GPQA Diamond (Artificial Analysis run)	Not measured	83.8%	Only Kimi K2 Thinking measured
Humanity's Last Exam (Artificial Analysis run)	Not measured	23.8%	Only Kimi K2 Thinking measured
GPQA Diamond (Epoch AI run)	82.3%	Not measured	Only Claude Sonnet 4.5 measured
ARC-AGI	63.7%	Not measured	Only Claude Sonnet 4.5 measured
ARC-AGI-2	13.6%	Not measured	Only Claude Sonnet 4.5 measured
SimpleBench	54.3%	Not measured	Only Claude Sonnet 4.5 measured
Chess puzzles	10.0%	Not measured	Only Claude Sonnet 4.5 measured
Mystery game puzzles	17.0%	Not measured	Only Claude Sonnet 4.5 measured
EBR-bench	2.4%	Not measured	Only Claude Sonnet 4.5 measured
VPCT	39.8%	Not measured	Only Claude Sonnet 4.5 measured
LMArena Text: hard prompts	1462	Not measured	Only Claude Sonnet 4.5 measured
LMArena Text: expert	1483	Not measured	Only Claude Sonnet 4.5 measured
LMArena Text: hard prompts in English	1471	Not measured	Only Claude Sonnet 4.5 measured
Kagi LLM Benchmark	57.9%	Not measured	Only Claude Sonnet 4.5 measured
Neither model has a result on the other 6 boards here

MathLike-for-likePublic boards, shown as published, kept out of the index20

Math benchmarks for Claude Sonnet 4.5 and Kimi K2 Thinking
Benchmark	Claude Sonnet 4.5	Kimi K2 Thinking	Leader
AIME	88.2%	85.4%	Claude Sonnet 4.5
MGSM (Vals AI)	94.3%	90.2%	Claude Sonnet 4.5
AA Math Index	Not measured	94.7	Only Kimi K2 Thinking measured
AIME 2025 (Artificial Analysis run)	Not measured	94.7%	Only Kimi K2 Thinking measured
OTIS Mock AIME	77.8%	Not measured	Only Claude Sonnet 4.5 measured
FrontierMath, tiers 1 to 3	23.9%	Not measured	Only Claude Sonnet 4.5 measured
FrontierMath, tier 4	2.4%	Not measured	Only Claude Sonnet 4.5 measured
ProofBench	19.0%	Not measured	Only Claude Sonnet 4.5 measured
MATH level 5	97.7%	Not measured	Only Claude Sonnet 4.5 measured
LMArena Text: math	1449	Not measured	Only Claude Sonnet 4.5 measured
LMArena Text: mathematical work	1462	Not measured	Only Claude Sonnet 4.5 measured
Neither model has a result on the other 2 boards here

KnowledgeLike-for-likePublic boards, shown as published, kept out of the index51

Knowledge benchmarks for Claude Sonnet 4.5 and Kimi K2 Thinking
Benchmark	Claude Sonnet 4.5	Kimi K2 Thinking	Leader
MMLU Pro	87.4%	81.1%	Claude Sonnet 4.5
LegalBench (Vals AI)	84.1%	80.2%	Claude Sonnet 4.5
CaseLaw (Vals AI)	62.2%	65.7%	Kimi K2 Thinking
CorpFin (Vals AI)	62.0%	60.6%	Claude Sonnet 4.5
TaxEval (Vals AI)	73.3%	71.7%	Claude Sonnet 4.5
MortgageTax (Vals AI)	64.0%	Not measured	Only Claude Sonnet 4.5 measured
MedQA (Vals AI)	94.7%	92.6%	Claude Sonnet 4.5
MedCode (Vals AI)	44.1%	Not measured	Only Claude Sonnet 4.5 measured
MMLU Pro (Artificial Analysis run)	Not measured	84.8%	Only Kimi K2 Thinking measured
SimpleQA Verified	30.7%	Not measured	Only Claude Sonnet 4.5 measured
LMArena Text: science	1448	Not measured	Only Claude Sonnet 4.5 measured
LMArena Text: medicine and healthcare	1444	Not measured	Only Claude Sonnet 4.5 measured
LMArena Text: legal and government	1451	Not measured	Only Claude Sonnet 4.5 measured
LMArena Text: business and finance	1440	Not measured	Only Claude Sonnet 4.5 measured
FACTS Benchmark Suite	40.6%	Not measured	Only Claude Sonnet 4.5 measured
Neither model has a result on the other 3 boards here

Web designLike-for-likePublic boards, shown as published, kept out of the index10

Web design benchmarks for Claude Sonnet 4.5 and Kimi K2 Thinking
Benchmark	Claude Sonnet 4.5	Kimi K2 Thinking	Leader
Design Arena: websites	1189	1113	Claude Sonnet 4.5
Design Arena: UI components	1170	Not measured	Only Claude Sonnet 4.5 measured
Design Arena: game dev	1166	Not measured	Only Claude Sonnet 4.5 measured
Design Arena: data viz	1167	Not measured	Only Claude Sonnet 4.5 measured
Design Arena: 3D	1157	Not measured	Only Claude Sonnet 4.5 measured
Design Arena: all code categories	1182	Not measured	Only Claude Sonnet 4.5 measured
Design Arena: SVG	1115	Not measured	Only Claude Sonnet 4.5 measured
Design Arena: ASCII art	1205	Not measured	Only Claude Sonnet 4.5 measured
Neither model has a result on the other 1 board here

GeneralDirectional onlyPublic boards, shown as published, kept out of the index25 boards, none shared

General benchmarks for Claude Sonnet 4.5 and Kimi K2 Thinking
Benchmark	Claude Sonnet 4.5	Kimi K2 Thinking	Leader
SAGE (Vals AI)	36.1%	Not measured	Only Claude Sonnet 4.5 measured
MedScribe (Vals AI)	84.5%	Not measured	Only Claude Sonnet 4.5 measured
IFBench	Not measured	68.1%	Only Kimi K2 Thinking measured
Long context reasoning (AA-LCR)	Not measured	72.0%	Only Kimi K2 Thinking measured
DTBench	83.2%	Not measured	Only Claude Sonnet 4.5 measured
LMCA	38.8%	Not measured	Only Claude Sonnet 4.5 measured
CL-bench	Not measured	17.6%	Only Kimi K2 Thinking measured
LMArena Text	1438	Not measured	Only Claude Sonnet 4.5 measured
LMArena Text: instruction following	1459	Not measured	Only Claude Sonnet 4.5 measured
LMArena Text: creative writing	1442	Not measured	Only Claude Sonnet 4.5 measured
LMArena Text: English	1450	Not measured	Only Claude Sonnet 4.5 measured
LMArena Text: non-English	1425	Not measured	Only Claude Sonnet 4.5 measured
LMArena Text: Chinese	1460	Not measured	Only Claude Sonnet 4.5 measured
LMArena Text: German	1427	Not measured	Only Claude Sonnet 4.5 measured
LMArena Text: Japanese	1390	Not measured	Only Claude Sonnet 4.5 measured
LMArena Text: Korean	1402	Not measured	Only Claude Sonnet 4.5 measured
LMArena Text: French	1459	Not measured	Only Claude Sonnet 4.5 measured
LMArena Text: Spanish	1458	Not measured	Only Claude Sonnet 4.5 measured
LMArena Text: Russian	1437	Not measured	Only Claude Sonnet 4.5 measured
LMArena Text: Polish	1423	Not measured	Only Claude Sonnet 4.5 measured
LMArena Text: multi-turn	1465	Not measured	Only Claude Sonnet 4.5 measured
LMArena Text: longer queries	1475	Not measured	Only Claude Sonnet 4.5 measured
LMArena Text: writing and language	1442	Not measured	Only Claude Sonnet 4.5 measured
LMArena Text: entertainment and media	1428	Not measured	Only Claude Sonnet 4.5 measured
LMArena Document	1450	Not measured	Only Claude Sonnet 4.5 measured
Neither model has a result on the other 21 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 Thinking
Benchmark	Claude Sonnet 4.5	Kimi K2 Thinking	Leader
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 Thinking$0.0019Fits in one request

Kimi K2 Thinking costs less

Repository review

50K input + 3K output tokens

Claude Sonnet 4.5$0.195Fits in one request

Kimi K2 Thinking$0.037Fits in one request

Kimi K2 Thinking costs less

Agent loop

200K input + 10K output tokens

Claude Sonnet 4.5$0.750Fits in one request

Kimi K2 Thinking$0.145Fits in one request

Kimi K2 Thinking 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 Thinking
Specification	Anthropic Claude Sonnet 4.5	MoonshotAI Kimi K2 Thinking
Maker	Anthropic	Moonshot AI
Weights	No public weights listed	Open weights
Released	September 29, 2025	November 6, 2025
Context window	1M	262K
Input $/Mtok	$3.00	$0.60
Output $/Mtok	$15.00	$2.50
Coding index	39.5	Not benchmarked
Independent measurements behind it	3	1
Cost per solved task	$1.16	$0.61
Source	OpenRouter listing	OpenRouter listing

Questions

Is Claude Sonnet 4.5 better than Kimi K2 Thinking for coding?

Only Claude Sonnet 4.5 has a coding score, 39.5 on the Vibe Coding Index; Kimi K2 Thinking has none, so the two cannot be ranked on coding. Pick Kimi K2 Thinking for output tokens 6.0x cheaper ($2.50 vs $15.00 per million) and a lower cost per solved task ($0.61 against $1.16).

Which is cheaper, Claude Sonnet 4.5 or Kimi K2 Thinking?

Claude Sonnet 4.5 costs $3.00 per million input tokens and $15.00 per million output tokens; Kimi K2 Thinking costs $0.60 and $2.50. Per solved SWE-bench Verified task, Claude Sonnet 4.5 costs $1.16 and Kimi K2 Thinking $0.61.

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

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

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

18 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 Thinking's on 1. Where only one model has a result, the page says so instead of naming a winner.

Claude Sonnet 4.5 or Kimi K2 Thinking: which to pick

Which one for your work

Coding

Intelligence

Agentic work

Reasoning

Math

Knowledge

Web design

Long documents

Everyday cost

Cost per solved task

At a glance

Benchmark by benchmark

What each workload costs

Chat turn

Repository review

Agent loop

Specification differences

Questions

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