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GPT-5.1 vs Kimi K2.5

Updated October 21, 2026. 84 benchmarks have a result for both. Coding is ranked on the Vibe Coding Index; every other board is shown as published.

Replace GPT-5.1 Replace Kimi K2.5
GPT-5.1OpenAI
Coding
53.3
Overall
24.7
Output $/M
$10.00
38
Kimi K2.5Moonshot AI
Coding
58.5
Overall
23.5
Output $/M
$2.50
45
vs boards won of 84 shared, 1 tied

Decision reading

Pick Kimi K2.5 for coding: it scores 58.5 on the Vibe Coding Index against 53.3 for GPT-5.1.

Pick GPT-5.1 when the context window is larger, 400K against 262K tokens, or when what matters is AA Coding Index or LiveCodeBench (Vals AI), where it leads.

Model AGPT-5.1OpenAI53.3/1002 independent benchmarks$1.02 per solved taskModel BKimi K2.5Moonshot AI58.5/1002 independent benchmarks$0.24 per solved task
Shared results
84
GPT-5.1 only
16
Kimi K2.5 only
14
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
GPT-5.1 53.3 from 2 benchmarks, Kimi K2.5 58.5 from 2 benchmarks.
Widest category
Agentic work, 7.9 points apart on average over 2 shared benchmarks.
Widest single gap
LMArena WebDev: React: GPT-5.1 1307 against Kimi K2.5 1429, 20.4 points apart on a 0 to 100 scale.
Output price
GPT-5.1 $10.00 against Kimi K2.5 $2.50 per million output tokens, 4.0x apart.
Context window
GPT-5.1 takes 400K 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
CategoryGPT-5.1BarsKimi K2.5Ties
Coding68
Intelligence20
Agentic work11
Reasoning75
Math03
Knowledge102
Web design071 tie
General1219
All shared boards38451 tie
CodingLike-for-likeFour of these boards feed the Vibe Coding Index68
Coding benchmarks for GPT-5.1 and Kimi K2.5
BenchmarkGPT-5.1Kimi K2.5Leader
SWE-bench Verified66.0%70.8%Kimi K2.5
SWE-bench MultilingualNot measured67.3%Only Kimi K2.5 measured
LMArena WebDev13961437Kimi K2.5
AA Coding Index49.446.8GPT-5.1
LiveCodeBench (Vals AI)86.5%83.9%GPT-5.1
SWE-bench Verified (Vals AI)69.8%70.0%Kimi K2.5
Vibe Code Bench (Vals AI)24.6%17.5%GPT-5.1
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
LiveCodeBench (Artificial Analysis run)86.8%Not measuredOnly GPT-5.1 measured
Terminal-Bench Hard (Artificial Analysis run)45.5%34.8%GPT-5.1
Terminal-Bench47.6%43.2%GPT-5.1
GSO-Bench13.7%Not measuredOnly GPT-5.1 measured
WeirdML60.8%45.6%GPT-5.1
ALE-BenchNot measured821.6Only Kimi K2.5 measured
LMArena Text: coding14531483Kimi K2.5
LMArena Text: software and IT14541471Kimi K2.5
LMArena WebDev: React13071429Kimi K2.5
LMArena WebDev: HTML14051426Kimi K2.5
LMArena WebDev: from an image14211439Kimi K2.5
Neither model has a result on the other 18 boards here
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index20
Intelligence benchmarks for GPT-5.1 and Kimi K2.5
BenchmarkGPT-5.1Kimi K2.5Leader
AA Intelligence Index24.723.5GPT-5.1
Epoch Capabilities Index149.8148.1GPT-5.1
Agentic workLike-for-likePublic boards, shown as published, kept out of the index11
Agentic work benchmarks for GPT-5.1 and Kimi K2.5
BenchmarkGPT-5.1Kimi K2.5Leader
Design Arena: agents building web appsNot measured1136Only Kimi K2.5 measured
Design Arena: agents building full-stack appsNot measured1114Only Kimi K2.5 measured
Design Arena: agents building mobile appsNot measured1147Only Kimi K2.5 measured
Design Arena: agents building Android appsNot measured1124Only 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 Telecom81.9%95.9%Kimi K2.5
DeepResearch Bench42.8%Not measuredOnly GPT-5.1 measured
OSWorldNot measured63.3%Only Kimi K2.5 measured
Vending-Bench 2$1,473$1,198GPT-5.1
Neither model has a result on the other 27 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index75
Reasoning benchmarks for GPT-5.1 and Kimi K2.5
BenchmarkGPT-5.1Kimi K2.5Leader
GPQA Diamond86.6%84.1%GPT-5.1
MMMU Pro (Vals AI)83.2%84.3%Kimi K2.5
GPQA Diamond (Artificial Analysis run)87.3%87.9%Kimi K2.5
Humanity's Last Exam (Artificial Analysis run)28.5%30.7%Kimi K2.5
GPQA Diamond (Epoch AI run)87.6%Not measuredOnly GPT-5.1 measured
ARC-AGI72.8%65.3%GPT-5.1
ARC-AGI-217.6%11.8%GPT-5.1
SimpleBench53.2%46.8%GPT-5.1
Chess puzzles42.0%Not measuredOnly GPT-5.1 measured
Mystery game puzzles19.0%Not measuredOnly GPT-5.1 measured
VPCT58.7%Not measuredOnly GPT-5.1 measured
LMArena Text: hard prompts14571453GPT-5.1
LMArena Text: expert14701466GPT-5.1
LMArena Text: hard prompts in English14621460GPT-5.1
LMArena Vision: diagrams12641282Kimi K2.5
LMArena Vision: homework12721297Kimi K2.5
Neither model has a result on the other 5 boards here
MathLike-for-likePublic boards, shown as published, kept out of the index03
Math benchmarks for GPT-5.1 and Kimi K2.5
BenchmarkGPT-5.1Kimi K2.5Leader
AIME93.3%95.6%Kimi K2.5
MGSM (Vals AI)93.0%Not measuredOnly GPT-5.1 measured
AA Math Index94.0Not measuredOnly GPT-5.1 measured
AIME 2025 (Artificial Analysis run)94.0%Not measuredOnly GPT-5.1 measured
OTIS Mock AIME88.6%Not measuredOnly GPT-5.1 measured
LMArena Text: math14461470Kimi K2.5
LMArena Text: mathematical work14491473Kimi K2.5
Neither model has a result on the other 6 boards here
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index102
Knowledge benchmarks for GPT-5.1 and Kimi K2.5
BenchmarkGPT-5.1Kimi K2.5Leader
MMLU Pro86.4%85.9%GPT-5.1
LegalBench (Vals AI)85.7%Not measuredOnly GPT-5.1 measured
CaseLaw (Vals AI)73.4%58.7%GPT-5.1
CorpFin (Vals AI)63.8%68.3%Kimi K2.5
TaxEval (Vals AI)74.9%74.2%GPT-5.1
MortgageTax (Vals AI)61.4%66.5%Kimi K2.5
MedQA (Vals AI)96.4%94.4%GPT-5.1
MedCode (Vals AI)52.7%39.3%GPT-5.1
MMLU Pro (Artificial Analysis run)87.0%Not measuredOnly GPT-5.1 measured
SimpleQA Verified48.0%34.3%GPT-5.1
LMArena Text: science14591459GPT-5.1
LMArena Text: medicine and healthcare14561448GPT-5.1
LMArena Text: legal and government14591441GPT-5.1
LMArena Text: business and finance14311427GPT-5.1
Neither model has a result on the other 3 boards here
Web designLike-for-likePublic boards, shown as published, kept out of the index07
Web design benchmarks for GPT-5.1 and Kimi K2.5
BenchmarkGPT-5.1Kimi K2.5Leader
Design Arena: websites11871249Kimi K2.5
Design Arena: UI components11661236Kimi K2.5
Design Arena: game dev11791207Kimi K2.5
Design Arena: data viz12041219Kimi K2.5
Design Arena: 3D10611205Kimi K2.5
Design Arena: all code categories11711236Kimi K2.5
Design Arena: SVG11491149Tie
Design Arena: ASCII art11181165Kimi K2.5
Neither model has a result on the other 1 board here
GeneralLike-for-likePublic boards, shown as published, kept out of the index1219
General benchmarks for GPT-5.1 and Kimi K2.5
BenchmarkGPT-5.1Kimi K2.5Leader
SAGE (Vals AI)43.2%49.9%Kimi K2.5
MedScribe (Vals AI)88.1%76.4%GPT-5.1
IFBench72.9%70.2%GPT-5.1
Long context reasoning (AA-LCR)80.0%78.0%GPT-5.1
DTBench90.1%Not measuredOnly GPT-5.1 measured
LMCA43.9%Not measuredOnly GPT-5.1 measured
Fiction.LiveBenchNot measured86.1%Only Kimi K2.5 measured
CL-bench23.7%19.3%GPT-5.1
CL-bench Life17.3%13.2%GPT-5.1
LMArena Text14431445Kimi K2.5
LMArena Text: instruction following14431431GPT-5.1
LMArena Text: creative writing14271422GPT-5.1
LMArena Vision12501269Kimi K2.5
LMArena Text: English14511453Kimi K2.5
LMArena Text: non-English14311433Kimi K2.5
LMArena Text: Chinese14951494GPT-5.1
LMArena Text: German14381441Kimi K2.5
LMArena Text: Japanese14531423GPT-5.1
LMArena Text: Korean14011412Kimi K2.5
LMArena Text: French14501454Kimi K2.5
LMArena Text: Spanish14331450Kimi K2.5
LMArena Text: Russian14351435Kimi K2.5
LMArena Text: Polish14401445Kimi K2.5
LMArena Text: multi-turn14501444GPT-5.1
LMArena Text: longer queries14481445GPT-5.1
LMArena Text: writing and language14281425GPT-5.1
LMArena Text: entertainment and media14151417Kimi K2.5
LMArena Vision: English12521274Kimi K2.5
LMArena Vision: Chinese12701328Kimi K2.5
LMArena Vision: reading text12551276Kimi K2.5
LMArena Vision: humor12631284Kimi K2.5
LMArena Vision: captioning12521257Kimi K2.5
LMArena Vision: recognizing things12321285Kimi K2.5
LMArena Vision: creative writing12661269Kimi K2.5
LMArena Document1403Not measuredOnly GPT-5.1 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 GPT-5.1 and Kimi K2.5
BenchmarkGPT-5.1Kimi 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

GPT-5.1$0.0063Fits in one request
Kimi K2.5$0.0018Fits in one request

Kimi K2.5 costs less

Repository review

50K input + 3K output tokens

GPT-5.1$0.092Fits in one request
Kimi K2.5$0.033Fits in one request

Kimi K2.5 costs less

Agent loop

200K input + 10K output tokens

GPT-5.1$0.350Fits in one request
Kimi K2.5$0.125Fits 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 GPT-5.1 and Kimi K2.5
SpecificationOpenAI GPT-5.1MoonshotAI Kimi K2.5
MakerOpenAIMoonshot AI
WeightsNo public weights listedOpen weights
ReleasedNovember 13, 2025January 27, 2026
Context window400K262K
Input $/Mtok$1.25$0.50
Output $/Mtok$10.00$2.50
Coding index53.358.5
Independent measurements behind it22
Cost per solved task$1.02$0.24
SourceOpenRouter listingOpenRouter listing

Questions

Is GPT-5.1 better than Kimi K2.5 for coding?

Pick Kimi K2.5 for coding: it scores 58.5 on the Vibe Coding Index against 53.3 for GPT-5.1. Pick GPT-5.1 when the context window is larger, 400K against 262K tokens, or when what matters is AA Coding Index or LiveCodeBench (Vals AI), where it leads.

Which is cheaper, GPT-5.1 or Kimi K2.5?

GPT-5.1 costs $1.25 per million input tokens and $10.00 per million output tokens; Kimi K2.5 costs $0.50 and $2.50. Per solved SWE-bench Verified task, GPT-5.1 costs $1.02 and Kimi K2.5 $0.24.

Which has the bigger context window, GPT-5.1 or Kimi K2.5?

GPT-5.1, with 400K tokens against 262K.

How many benchmarks is the GPT-5.1 vs Kimi K2.5 comparison based on?

84 benchmarks have a result for both models as of October 21, 2026. GPT-5.1's coding index rests on 2 independent benchmarks and Kimi K2.5's on 2. Where only one model has a result, the page says so instead of naming a winner.

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