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Claude Opus 5.5 vs Kimi K3

Updated October 21, 2026. 91 benchmarks have a result for both. Coding is ranked on the Vibe Coding Index; every other board is shown as published.

Replace Claude Opus 5.5 Replace Kimi K3
Claude Opus 5.5Anthropic
Coding
92.2
Overall
57.6
Output $/M
$20.00
85
Kimi K3Moonshot AI
Coding
61.8
Overall
43.6
Output $/M
$11.936
6
vs boards won of 91 shared

Decision reading

Pick Claude Opus 5.5 for coding: it scores 92.2 on the Vibe Coding Index against 61.8 for Kimi K3.

Pick Kimi K3 when output tokens cost 1.7x less, or when the context window is larger, 1.05M against 1M tokens.

Model AClaude Opus 5.5Anthropic92.2/1002 independent benchmarksNo cost per solved taskModel BKimi K3Moonshot AI61.8/1002 independent benchmarks$0.81 per solved task
Shared results
91
Claude Opus 5.5 only
16
Kimi K3 only
26
Like-for-like categories
8 of 9

Shared results can support a head-to-head reading. Results only one model has describe coverage, not superiority.

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 Opus 5.5 92.2 from 2 benchmarks, Kimi K3 61.8 from 2 benchmarks.
Widest category
Agentic work, 23.6 points apart on average over 16 shared benchmarks.
Widest single gap
Time Horizon Index (Vals AI): Claude Opus 5.5 91.3% against Kimi K3 10.5%, 80.8 points apart on a 0 to 100 scale.
Output price
Claude Opus 5.5 $20.00 against Kimi K3 $11.936 per million output tokens, 1.7x apart.
Context window
Claude Opus 5.5 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 Opus 5.5BarsKimi K3Ties
Coding191
Intelligence20
Agentic work151
Reasoning91
Math60
Knowledge60
Web design71
General212
All shared boards856
CodingLike-for-likeFour of these boards feed the Vibe Coding Index191
Coding benchmarks for Claude Opus 5.5 and Kimi K3
BenchmarkClaude Opus 5.5Kimi K3Leader
LiveBench coding96.3%59.3%Claude Opus 5.5
LMArena WebDev18071655Claude Opus 5.5
AA Coding IndexNot measured76.2Only Kimi K3 measured
LiveCodeBench (Vals AI)Not measured87.2%Only Kimi K3 measured
SWE-bench Verified (Vals AI)Not measured93.4%Only Kimi K3 measured
Terminal-Bench 4 (Vals AI)65.2%17.2%Claude Opus 5.5
Vibe Code Bench (Vals AI)90.3%85.0%Claude Opus 5.5
Code migration (Vals AI)66.7%16.1%Claude Opus 5.5
ProgramBench (Vals AI)18.5%2.0%Claude Opus 5.5
IOI (Vals AI)95.1%48.9%Claude Opus 5.5
Terminal-Bench 2.1 (Vals AI)87.6%80.9%Claude Opus 5.5
SWE-bench Multimodal (Vals AI)70.2%44.2%Claude Opus 5.5
Vibe Code Bench 1-100 (Vals AI)30.4%18.2%Claude Opus 5.5
CyberBench (Vals AI)74.6%75.2%Kimi K3
SciCode66.9%59.5%Claude Opus 5.5
FrontierCode54.6%44.2%Claude Opus 5.5
FrontierSWE62.3%25.9%Claude Opus 5.5
WeirdMLNot measured82.6%Only Kimi K3 measured
MirrorCode77.4%Not measuredOnly Claude Opus 5.5 measured
ALE-Bench2147.41524.5Claude Opus 5.5
LMArena Text: coding15451508Claude Opus 5.5
LMArena Text: software and IT15381499Claude Opus 5.5
LMArena WebDev: React18551670Claude Opus 5.5
LMArena WebDev: HTML17531644Claude Opus 5.5
LMArena WebDev: from an image17531579Claude Opus 5.5
Neither model has a result on the other 13 boards here
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index20
Intelligence benchmarks for Claude Opus 5.5 and Kimi K3
BenchmarkClaude Opus 5.5Kimi K3Leader
AA Intelligence Index57.643.6Claude Opus 5.5
Epoch Capabilities Index168.8157.9Claude Opus 5.5
Agentic workLike-for-likePublic boards, shown as published, kept out of the index151
Agentic work benchmarks for Claude Opus 5.5 and Kimi K3
BenchmarkClaude Opus 5.5Kimi K3Leader
AA Agentic IndexNot measured50.0Only Kimi K3 measured
Design Arena: agents building web apps13161296Claude Opus 5.5
Design Arena: agents building full-stack appsNot measured1315Only Kimi K3 measured
Design Arena: agents building mobile apps13111267Claude Opus 5.5
Design Arena: agents building Android appsNot measured1256Only 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: spreadsheets13591058Claude Opus 5.5
LiveBench research85.0%79.0%Claude Opus 5.5
LiveBench browser80.0%16.0%Claude Opus 5.5
LiveBench long agentic85.0%42.8%Claude Opus 5.5
SREBench (Vals AI)33.6%Not measuredOnly Claude Opus 5.5 measured
Finance Agent (Vals AI)58.6%53.1%Claude Opus 5.5
Tax Agent Bench (Vals AI)45.6%33.4%Claude Opus 5.5
Legal Research Bench (Vals AI)50.5%46.1%Claude Opus 5.5
Harvey's Legal Agent Benchmark (Vals AI)9.2%12.9%Kimi K3
Excel Modeling Benchmark (Vals AI)75.9%66.7%Claude Opus 5.5
BioMysteryBench (Vals AI)79.3%72.6%Claude Opus 5.5
Terminal-Bench-Science (Vals AI)47.1%1.4%Claude Opus 5.5
Vals Science Index58.7%Not measuredOnly Claude Opus 5.5 measured
Time Horizon Index (Vals AI)91.3%10.5%Claude Opus 5.5
CUA-bench (Vals AI)14.0%Not measuredOnly Claude Opus 5.5 measured
Robo-bench (Vals AI)14.6%Not measuredOnly Claude Opus 5.5 measured
APEX-Agents73.5%47.8%Claude Opus 5.5
Remote Labor Index21.3%Not measuredOnly Claude Opus 5.5 measured
PostTrainBenchNot measured32.0%Only Kimi K3 measured
SpireClimb3.3%Not measuredOnly Claude Opus 5.5 measured
Vending-Bench 2$9,235$5,165Claude Opus 5.5
LMArena Search1213Not measuredOnly Claude Opus 5.5 measured
Neither model has a result on the other 8 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index91
Reasoning benchmarks for Claude Opus 5.5 and Kimi K3
BenchmarkClaude Opus 5.5Kimi K3Leader
GPQA DiamondNot measured92.9%Only Kimi K3 measured
LiveBench reasoning92.2%90.7%Claude Opus 5.5
MysteryMechanism (Vals AI)49.5%Not measuredOnly Claude Opus 5.5 measured
MMMU Pro (Vals AI)Not measured88.2%Only Kimi K3 measured
GPQA Diamond (Artificial Analysis run)Not measured93.5%Only Kimi K3 measured
Humanity's Last Exam (Artificial Analysis run)61.4%46.9%Claude Opus 5.5
GPQA Diamond (Epoch AI run)90.6%93.1%Kimi K3
ARC-AGI98.5%94.5%Claude Opus 5.5
ARC-AGI-293.3%60.4%Claude Opus 5.5
SimpleBenchNot measured60.7%Only Kimi K3 measured
Chess puzzles67.0%37.0%Claude Opus 5.5
Mystery game puzzles71.0%26.0%Claude Opus 5.5
EBR-bench71.4%Not measuredOnly Claude Opus 5.5 measured
LMArena Text: hard prompts15361495Claude Opus 5.5
LMArena Text: expert15491520Claude Opus 5.5
LMArena Text: hard prompts in English15351496Claude Opus 5.5
LMArena Vision: diagrams1345Not measuredOnly Claude Opus 5.5 measured
LMArena Vision: homework1362Not measuredOnly Claude Opus 5.5 measured
Neither model has a result on the other 3 boards here
MathLike-for-likePublic boards, shown as published, kept out of the index60
Math benchmarks for Claude Opus 5.5 and Kimi K3
BenchmarkClaude Opus 5.5Kimi K3Leader
OTIS Mock AIME100.0%97.2%Claude Opus 5.5
FrontierMath, tiers 1 to 391.2%72.2%Claude Opus 5.5
FrontierMath, tier 495.0%39.0%Claude Opus 5.5
ProofBench100.0%87.0%Claude Opus 5.5
LMArena Text: math15181494Claude Opus 5.5
LMArena Text: mathematical work15161505Claude Opus 5.5
Neither model has a result on the other 7 boards here
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index60
Knowledge benchmarks for Claude Opus 5.5 and Kimi K3
BenchmarkClaude Opus 5.5Kimi K3Leader
MMLU ProNot measured88.0%Only Kimi K3 measured
LegalBench (Vals AI)Not measured86.2%Only Kimi K3 measured
CorpFin (Vals AI)Not measured71.6%Only Kimi K3 measured
TaxEval (Vals AI)Not measured75.7%Only Kimi K3 measured
MortgageTax (Vals AI)Not measured66.3%Only Kimi K3 measured
MedCode (Vals AI)49.8%49.4%Claude Opus 5.5
SimpleQA Verified72.2%50.6%Claude Opus 5.5
LMArena Text: science15241508Claude Opus 5.5
LMArena Text: medicine and healthcare15091489Claude Opus 5.5
LMArena Text: legal and government15181503Claude Opus 5.5
LMArena Text: business and finance14941470Claude Opus 5.5
Neither model has a result on the other 6 boards here
Web designLike-for-likePublic boards, shown as published, kept out of the index71
Web design benchmarks for Claude Opus 5.5 and Kimi K3
BenchmarkClaude Opus 5.5Kimi K3Leader
Design Arena: websites13351336Kimi K3
Design Arena: UI components13901345Claude Opus 5.5
Design Arena: game dev14571361Claude Opus 5.5
Design Arena: data viz13971350Claude Opus 5.5
Design Arena: 3D14771388Claude Opus 5.5
Design Arena: all code categories13901361Claude Opus 5.5
Design Arena: SVG13321301Claude Opus 5.5
LiveBench design86.9%77.2%Claude Opus 5.5
Neither model has a result on the other 1 board here
GeneralLike-for-likePublic boards, shown as published, kept out of the index212
General benchmarks for Claude Opus 5.5 and Kimi K3
BenchmarkClaude Opus 5.5Kimi K3Leader
Vals Index70.2%53.0%Claude Opus 5.5
LiveBench data analysis80.3%78.7%Claude Opus 5.5
Public Benefits Bench (Vals AI)70.6%68.2%Claude Opus 5.5
SAGE (Vals AI)45.8%52.8%Kimi K3
MedScribe (Vals AI)91.4%88.0%Claude Opus 5.5
Vals Multimodal IndexNot measured73.4%Only Kimi K3 measured
Long context reasoning (AA-LCR)84.7%88.7%Kimi K3
DTBench98.9%91.2%Claude Opus 5.5
LMCA68.2%52.7%Claude Opus 5.5
Surface Evolver BenchNot measured95.0%Only Kimi K3 measured
Furniture assembly83.3%34.2%Claude Opus 5.5
LMArena Text15161476Claude Opus 5.5
LMArena Text: instruction following15371485Claude Opus 5.5
LMArena Text: creative writing15351457Claude Opus 5.5
LMArena Vision1321Not measuredOnly Claude Opus 5.5 measured
LMArena Text: English15191481Claude Opus 5.5
LMArena Text: non-English15071466Claude Opus 5.5
LMArena Text: Chinese15821529Claude Opus 5.5
LMArena Text: GermanNot measured1490Only Kimi K3 measured
LMArena Text: Japanese15341494Claude Opus 5.5
LMArena Text: KoreanNot measured1460Only Kimi K3 measured
LMArena Text: French14931492Claude Opus 5.5
LMArena Text: Spanish15081472Claude Opus 5.5
LMArena Text: Russian15171485Claude Opus 5.5
LMArena Text: PolishNot measured1458Only Kimi K3 measured
LMArena Text: multi-turn15011489Claude Opus 5.5
LMArena Text: longer queries15321494Claude Opus 5.5
LMArena Text: writing and language15321471Claude Opus 5.5
LMArena Text: entertainment and media15151453Claude Opus 5.5
LMArena Vision: English1317Not measuredOnly Claude Opus 5.5 measured
LMArena Vision: reading text1326Not measuredOnly Claude Opus 5.5 measured
LMArena Vision: creative writing1320Not measuredOnly Claude Opus 5.5 measured
Neither model has a result on the other 14 boards here
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
Image generation benchmarks for Claude Opus 5.5 and Kimi K3
BenchmarkClaude Opus 5.5Kimi 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 Opus 5.5$0.014Fits in one request
Kimi K3$0.0062Fits in one request

Kimi K3 costs less

Repository review

50K input + 3K output tokens

Claude Opus 5.5$0.260Fits in one request
Kimi K3$0.048Fits in one request

Kimi K3 costs less

Agent loop

200K input + 10K output tokens

Claude Opus 5.5$1.00Fits in one request
Kimi K3$0.167Fits in one request

Kimi K3 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 Opus 5.5 and Kimi K3
SpecificationAnthropic Claude Opus 5.5MoonshotAI Kimi K3
MakerAnthropicMoonshot AI
WeightsNo public weights listedOpen weights
ReleasedSeptember 22, 2026July 16, 2026
Context window1M1.05M
Input $/Mtok$4.00$0.239
Output $/Mtok$20.00$11.936
Coding index92.261.8
Independent measurements behind it22
Cost per solved taskNot computable$0.81
SourceOpenRouter listingOpenRouter listing

Questions

Is Claude Opus 5.5 better than Kimi K3 for coding?

Pick Claude Opus 5.5 for coding: it scores 92.2 on the Vibe Coding Index against 61.8 for Kimi K3. Pick Kimi K3 when output tokens cost 1.7x less, or when the context window is larger, 1.05M against 1M tokens.

Which is cheaper, Claude Opus 5.5 or Kimi K3?

Claude Opus 5.5 costs $4.00 per million input tokens and $20.00 per million output tokens; Kimi K3 costs $0.239 and $11.936. Cost per solved task is known for Kimi K3 only.

Which has the bigger context window, Claude Opus 5.5 or Kimi K3?

Kimi K3, with 1.05M tokens against 1M.

How many benchmarks is the Claude Opus 5.5 vs Kimi K3 comparison based on?

91 benchmarks have a result for both models as of October 21, 2026. Claude Opus 5.5's coding index rests on 2 independent benchmarks and Kimi K3's on 2. Where only one model has a result, the page says so instead of naming a winner.

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