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GPT-5.5 vs Kimi K3

GPT-5.5 leads Kimi K3 on coding, 71.3 to 62.3 on the Vibe Coding Index, and Kimi K3 costs 2.0x less per output token ($15.00 vs $30.00 per million). Updated October 21, 2026; 106 benchmarks have a result for both.

Replace GPT-5.5 Replace Kimi K3
GPT-5.5OpenAI
Coding
71.3
Overall
69.2
Output $/M
$30.00
32
Kimi K3Moonshot AI
Coding
62.3
Overall
66.5
Output $/M
$15.00
73
vs boards won of 106 shared, 1 tied

GPT-5.5 or Kimi K3: which to pick

Pick GPT-5.5 for coding: it scores 71.3 on the Vibe Coding Index against 62.3 for Kimi K3, though on 5 benchmarks against 6.

Pick Kimi K3 for output tokens 2.0x cheaper ($15.00 vs $30.00 per million) and a lower cost per solved task ($0.81 against $1.65).

Model AGPT-5.5OpenAI71.3/1005 independent benchmarks$1.65 per solved taskModel BKimi K3Moonshot AI62.3/1006 independent benchmarks$0.81 per solved task
Shared results
106
GPT-5.5 only
28
Kimi K3 only
11
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
GPT-5.5 71.3 from 5 benchmarks, Kimi K3 62.3 from 6 benchmarks.
Widest category
Math, 16.5 points apart on average over 6 shared benchmarks.
Widest single gap
ProofBench: GPT-5.5 50.0% against Kimi K3 87.0%, 37.0 points apart on a 0 to 100 scale.
Output price
GPT-5.5 $30.00 against Kimi K3 $15.00 per million output tokens, 2.0x apart.
Context window
GPT-5.5 takes 1.05M 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
CategoryGPT-5.5BarsKimi K3Ties
Coding414
Intelligence11
Agentic work416
Reasoning761 tie
Math24
Knowledge56
Web design08
General918
All shared boards32731 tie
CodingLike-for-likeSix of these boards feed the Vibe Coding Index414
Coding benchmarks for GPT-5.5 and Kimi K3
BenchmarkGPT-5.5Kimi K3Leader
LiveBench coding85.1%59.3%GPT-5.5
LMArena WebDev15131655Kimi K3
AA Coding Index74.976.2Kimi K3
LiveCodeBench (Vals AI)85.3%87.2%Kimi K3
SWE-bench Verified (Vals AI)82.6%93.4%Kimi K3
Terminal-Bench 4 (Vals AI)Not measured17.2%Only Kimi K3 measured
Vibe Code Bench (Vals AI)69.8%85.0%Kimi K3
Code migration (Vals AI)45.2%16.1%GPT-5.5
ProgramBench (Vals AI)0.5%2.0%Kimi K3
IOI (Vals AI)Not measured48.9%Only Kimi K3 measured
Terminal-Bench 2.1 (Vals AI)76.4%80.9%Kimi K3
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
SkillsBench (Vals AI)62.5%Not measuredOnly GPT-5.5 measured
CyberBench (Vals AI)Not measured75.2%Only Kimi K3 measured
SciCode56.1%59.5%Kimi K3
Terminal-Bench Hard (Artificial Analysis run)60.6%Not measuredOnly GPT-5.5 measured
Terminal-Bench84.7%Not measuredOnly GPT-5.5 measured
FrontierCode43.0%44.2%Kimi K3
FrontierSWENot measured25.9%Only Kimi K3 measured
GSO-Bench40.2%Not measuredOnly GPT-5.5 measured
WeirdML84.9%82.6%GPT-5.5
MirrorCode10.0%Not measuredOnly GPT-5.5 measured
ALE-Bench1943.01524.5GPT-5.5
LMArena Text: coding14941508Kimi K3
LMArena Text: software and IT14931499Kimi K3
LMArena WebDev: React15061670Kimi K3
LMArena WebDev: HTML15431644Kimi K3
LMArena WebDev: from an image15321579Kimi K3
Neither model has a result on the other 10 boards here
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index11
Intelligence benchmarks for GPT-5.5 and Kimi K3
BenchmarkGPT-5.5Kimi K3Leader
AA Intelligence Index38.443.6Kimi K3
Epoch Capabilities Index159.7157.9GPT-5.5
Agentic workLike-for-likePublic boards, shown as published, kept out of the index416
Agentic work benchmarks for GPT-5.5 and Kimi K3
BenchmarkGPT-5.5Kimi K3Leader
AA Agentic Index36.450.0Kimi K3
Design Arena: agents building web apps11171295Kimi K3
Design Arena: agents building full-stack apps10891315Kimi K3
Design Arena: agents building mobile apps11431269Kimi K3
Design Arena: agents building Android apps11631250Kimi K3
Design Arena: agents building Godot games11731223Kimi K3
Design Arena: agents building games11791252Kimi K3
Design Arena: HTML slides10671256Kimi K3
Design Arena: PowerPoint slides11091273Kimi K3
Design Arena: spreadsheetsNot measured1058Only Kimi K3 measured
LiveBench research61.6%79.0%Kimi K3
LiveBench browser48.0%16.0%GPT-5.5
LiveBench long agentic44.6%42.8%GPT-5.5
SREBench (Vals AI)3.8%Not measuredOnly GPT-5.5 measured
Finance Agent (Vals AI)51.8%53.1%Kimi K3
Tax Agent Bench (Vals AI)21.8%33.4%Kimi K3
Legal Research Bench (Vals AI)40.4%46.1%Kimi K3
Harvey's Legal Agent Benchmark (Vals AI)Not measured12.9%Only Kimi K3 measured
Excel Modeling Benchmark (Vals AI)64.5%66.7%Kimi K3
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)8.3%10.5%Kimi K3
τ²-Bench Telecom93.9%Not measuredOnly GPT-5.5 measured
APEX-Agents55.1%47.8%GPT-5.5
Remote Labor Index6.3%Not measuredOnly GPT-5.5 measured
OSWorld 2.013.0%Not measuredOnly GPT-5.5 measured
DeepResearch Bench54.0%Not measuredOnly GPT-5.5 measured
PostTrainBench27.2%32.0%Kimi K3
Vending-Bench 2$7,524$5,165GPT-5.5
Neither model has a result on the other 12 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index76
Reasoning benchmarks for GPT-5.5 and Kimi K3
BenchmarkGPT-5.5Kimi K3Leader
GPQA Diamond93.2%92.9%GPT-5.5
LiveBench reasoning89.7%90.7%Kimi K3
MMMU Pro (Vals AI)88.3%88.2%GPT-5.5
GPQA Diamond (Artificial Analysis run)93.5%93.5%Tie
Humanity's Last Exam (Artificial Analysis run)45.8%46.9%Kimi K3
GPQA Diamond (Epoch AI run)90.7%93.1%Kimi K3
ARC-AGI95.0%94.5%GPT-5.5
ARC-AGI-285.0%60.4%GPT-5.5
SimpleBench69.0%60.7%GPT-5.5
Chess puzzles63.0%37.0%GPT-5.5
Mystery game puzzles56.0%26.0%GPT-5.5
EBR-bench34.3%Not measuredOnly GPT-5.5 measured
LMArena Text: hard prompts14891495Kimi K3
LMArena Text: expert15071520Kimi K3
LMArena Text: hard prompts in English14831496Kimi K3
LMArena Vision: diagrams1325Not measuredOnly GPT-5.5 measured
LMArena Vision: homework1332Not measuredOnly GPT-5.5 measured
Kagi LLM Benchmark88.8%Not measuredOnly GPT-5.5 measured
Neither model has a result on the other 4 boards here
MathLike-for-likePublic boards, shown as published, kept out of the index24
Math benchmarks for GPT-5.5 and Kimi K3
BenchmarkGPT-5.5Kimi K3Leader
OTIS Mock AIME84.4%97.2%Kimi K3
FrontierMath, tiers 1 to 385.3%72.2%GPT-5.5
FrontierMath, tier 472.5%39.0%GPT-5.5
ProofBench50.0%87.0%Kimi K3
LMArena Text: math14871494Kimi K3
LMArena Text: mathematical work14961505Kimi K3
Neither model has a result on the other 7 boards here
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index56
Knowledge benchmarks for GPT-5.5 and Kimi K3
BenchmarkGPT-5.5Kimi K3Leader
MMLU Pro88.1%88.0%GPT-5.5
LegalBench (Vals AI)86.5%86.2%GPT-5.5
CaseLaw (Vals AI)66.2%Not measuredOnly GPT-5.5 measured
CorpFin (Vals AI)68.4%71.6%Kimi K3
TaxEval (Vals AI)75.0%75.7%Kimi K3
MortgageTax (Vals AI)68.8%66.3%GPT-5.5
MedCode (Vals AI)49.1%49.4%Kimi K3
SimpleQA Verified63.0%50.6%GPT-5.5
LMArena Text: science14851508Kimi K3
LMArena Text: medicine and healthcare14651489Kimi K3
LMArena Text: legal and government14911503Kimi K3
LMArena Text: business and finance14781470GPT-5.5
FACTS Benchmark Suite66.7%Not measuredOnly GPT-5.5 measured
Neither model has a result on the other 5 boards here
Web designLike-for-likePublic boards, shown as published, kept out of the index08
Web design benchmarks for GPT-5.5 and Kimi K3
BenchmarkGPT-5.5Kimi K3Leader
Design Arena: websites12561335Kimi K3
Design Arena: UI components12601344Kimi K3
Design Arena: game dev12941359Kimi K3
Design Arena: data viz12651351Kimi K3
Design Arena: 3D11981388Kimi K3
Design Arena: all code categories12601360Kimi K3
Design Arena: SVG12341302Kimi K3
Design Arena: ASCII art1255Not measuredOnly GPT-5.5 measured
LiveBench design70.3%77.2%Kimi K3
GeneralLike-for-likePublic boards, shown as published, kept out of the index918
General benchmarks for GPT-5.5 and Kimi K3
BenchmarkGPT-5.5Kimi K3Leader
Vals IndexNot measured53.0%Only Kimi K3 measured
LiveBench data analysis81.6%78.7%GPT-5.5
Public Benefits Bench (Vals AI)60.9%68.2%Kimi K3
SAGE (Vals AI)51.5%52.8%Kimi K3
MedScribe (Vals AI)86.9%88.0%Kimi K3
Vals Multimodal Index68.1%73.4%Kimi K3
IFBench75.9%Not measuredOnly GPT-5.5 measured
Long context reasoning (AA-LCR)84.3%88.7%Kimi K3
DTBench96.0%91.2%GPT-5.5
LMCA54.3%52.7%GPT-5.5
Surface Evolver Bench88.1%95.0%Kimi K3
Furniture assembly44.2%34.2%GPT-5.5
ExploitBench47.4%Not measuredOnly GPT-5.5 measured
CL-bench Life22.2%Not measuredOnly GPT-5.5 measured
LMArena Text14711476Kimi K3
LMArena Text: instruction following14781485Kimi K3
LMArena Text: creative writing14551457Kimi K3
LMArena Vision1297Not measuredOnly GPT-5.5 measured
LMArena Text: English14701481Kimi K3
LMArena Text: non-English14671466GPT-5.5
LMArena Text: Chinese15341529GPT-5.5
LMArena Text: German14801490Kimi K3
LMArena Text: Japanese14991494GPT-5.5
LMArena Text: Korean14601460GPT-5.5
LMArena Text: French14851492Kimi K3
LMArena Text: Spanish14681472Kimi K3
LMArena Text: Russian14731485Kimi K3
LMArena Text: Polish14651458GPT-5.5
LMArena Text: multi-turn14761489Kimi K3
LMArena Text: longer queries14841494Kimi K3
LMArena Text: writing and language14661471Kimi K3
LMArena Text: entertainment and media14491453Kimi K3
LMArena Vision: English1292Not measuredOnly GPT-5.5 measured
LMArena Vision: Chinese1360Not measuredOnly GPT-5.5 measured
LMArena Vision: reading text1306Not measuredOnly GPT-5.5 measured
LMArena Vision: humor1293Not measuredOnly GPT-5.5 measured
LMArena Vision: recognizing things1231Not measuredOnly GPT-5.5 measured
LMArena Vision: creative writing1301Not measuredOnly GPT-5.5 measured
LMArena Document1486Not measuredOnly GPT-5.5 measured
Neither model has a result on the other 7 boards here
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
Image generation benchmarks for GPT-5.5 and Kimi K3
BenchmarkGPT-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

GPT-5.5$0.020Fits in one request
Kimi K3$0.011Fits in one request

Kimi K3 costs less

Repository review

50K input + 3K output tokens

GPT-5.5$0.340Fits in one request
Kimi K3$0.195Fits in one request

Kimi K3 costs less

Agent loop

200K input + 10K output tokens

GPT-5.5$1.30Fits in one request
Kimi K3$0.750Fits 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 GPT-5.5 and Kimi K3
SpecificationOpenAI GPT-5.5MoonshotAI Kimi K3
MakerOpenAIMoonshot AI
WeightsNo public weights listedOpen weights
ReleasedApril 24, 2026July 16, 2026
Context window1.05M1.05M
Input $/Mtok$5.00$3.00
Output $/Mtok$30.00$15.00
Coding index71.362.3
Independent measurements behind it56
Cost per solved task$1.65$0.81
SourceOpenRouter listingOpenRouter listing

Questions

Is GPT-5.5 better than Kimi K3 for coding?

Pick GPT-5.5 for coding: it scores 71.3 on the Vibe Coding Index against 62.3 for Kimi K3, though on 5 benchmarks against 6. Pick Kimi K3 for output tokens 2.0x cheaper ($15.00 vs $30.00 per million) and a lower cost per solved task ($0.81 against $1.65).

Which is cheaper, GPT-5.5 or Kimi K3?

GPT-5.5 costs $5.00 per million input tokens and $30.00 per million output tokens; Kimi K3 costs $3.00 and $15.00. Per solved SWE-bench Verified task, GPT-5.5 costs $1.65 and Kimi K3 $0.81.

Which has the bigger context window, GPT-5.5 or Kimi K3?

GPT-5.5, with 1.05M tokens against 1.05M.

How many benchmarks is the GPT-5.5 vs Kimi K3 comparison based on?

106 benchmarks have a result for both models as of October 21, 2026. GPT-5.5's coding index rests on 5 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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