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GPT-5 Nano vs Kimi K2.5

Kimi K2.5 leads GPT-5 Nano on the Artificial Analysis Intelligence Index, 23.5 to 13.0, and GPT-5 Nano costs 7.1x less per output token ($0.40 vs $2.85 per million). Updated October 22, 2026; 68 benchmarks have a result for both.

Replace GPT-5 Nano Replace Kimi K2.5
GPT-5 NanoOpenAI
Coding
No data
Overall
35.6
Output $/M
$0.40
0
Kimi K2.5Moonshot AI
Coding
38.6
Overall
44.8
Output $/M
$2.85
68
vs boards won of 68 shared

GPT-5 Nano or Kimi K2.5: which to pick

Only Kimi K2.5 has a coding score, 38.6 on the Vibe Coding Index; GPT-5 Nano has none, so the two cannot be ranked on coding.

Pick GPT-5 Nano for output tokens 7.1x cheaper ($0.40 vs $2.85 per million) and a lower cost per solved task ($0.109 against $0.24).

Model AGPT-5 NanoOpenAINot benchmarkedNo coding benchmark$0.109 per solved taskModel BKimi K2.5Moonshot AI38.6/1003 independent benchmarks$0.24 per solved task
Shared results
68
GPT-5 Nano only
19
Kimi K2.5 only
31
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 Nano not benchmarked, Kimi K2.5 38.6 from 3 benchmarks.
Widest category
Agentic work, 59.4 points apart on average over 1 shared benchmark.
Widest single gap
τ²-Bench Telecom: GPT-5 Nano 36.5% against Kimi K2.5 95.9%, 59.4 points apart on a 0 to 100 scale.
Output price
GPT-5 Nano $0.40 against Kimi K2.5 $2.85 per million output tokens, 7.1x apart.
Context window
GPT-5 Nano 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 NanoBarsKimi K2.5Ties
Coding07
Intelligence02
Agentic work01
Reasoning012
Math03
Knowledge011
Web design06
General026
All shared boards068
CodingLike-for-likeSix of these boards feed the Vibe Coding Index07
Coding benchmarks for GPT-5 Nano and Kimi K2.5
BenchmarkGPT-5 NanoKimi K2.5Leader
SWE-bench Verified34.8%70.8%Kimi K2.5
SWE-bench MultilingualNot measured67.3%Only Kimi K2.5 measured
LMArena WebDevNot measured1437Only Kimi K2.5 measured
AA Coding IndexNot measured46.8Only Kimi K2.5 measured
LiveCodeBench (Vals AI)70.2%83.9%Kimi K2.5
SWE-bench Verified (Vals AI)Not measured70.0%Only Kimi K2.5 measured
Vibe Code Bench (Vals AI)Not measured17.5%Only Kimi K2.5 measured
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)78.9%Not measuredOnly GPT-5 Nano measured
Terminal-Bench Hard (Artificial Analysis run)17.4%34.8%Kimi K2.5
Terminal-Bench21.8%43.2%Kimi K2.5
WeirdML38.1%45.6%Kimi K2.5
ALE-BenchNot measured821.6Only Kimi K2.5 measured
LMArena Text: coding13511483Kimi K2.5
LMArena Text: software and IT13451471Kimi K2.5
LMArena WebDev: ReactNot measured1429Only Kimi K2.5 measured
LMArena WebDev: HTMLNot measured1426Only Kimi K2.5 measured
LMArena WebDev: from an imageNot measured1439Only Kimi K2.5 measured
Neither model has a result on the other 20 boards here
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index02
Intelligence benchmarks for GPT-5 Nano and Kimi K2.5
BenchmarkGPT-5 NanoKimi K2.5Leader
AA Intelligence Index13.023.5Kimi K2.5
Epoch Capabilities Index139.2148.1Kimi K2.5
Agentic workLike-for-likePublic boards, shown as published, kept out of the index01
Agentic work benchmarks for GPT-5 Nano and Kimi K2.5
BenchmarkGPT-5 NanoKimi 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 measured1118Only 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 Telecom36.5%95.9%Kimi K2.5
OSWorldNot measured63.3%Only Kimi K2.5 measured
Vending-Bench 2Not measured$1,198Only Kimi K2.5 measured
Berkeley Function Calling Leaderboard (BFCL)51.4%Not measuredOnly GPT-5 Nano measured
Neither model has a result on the other 29 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index012
Reasoning benchmarks for GPT-5 Nano and Kimi K2.5
BenchmarkGPT-5 NanoKimi K2.5Leader
GPQA Diamond63.4%84.1%Kimi K2.5
MMMU Pro (Vals AI)70.9%84.3%Kimi K2.5
GPQA Diamond (Artificial Analysis run)67.6%87.9%Kimi K2.5
Humanity's Last Exam (Artificial Analysis run)9.5%30.7%Kimi K2.5
GPQA Diamond (Epoch AI run)69.4%Not measuredOnly GPT-5 Nano measured
ARC-AGI20.7%65.3%Kimi K2.5
ARC-AGI-22.6%11.8%Kimi K2.5
SimpleBenchNot measured46.8%Only Kimi K2.5 measured
Chess puzzles22.0%Not measuredOnly GPT-5 Nano measured
Mystery game puzzles9.0%Not measuredOnly GPT-5 Nano measured
VPCT37.2%Not measuredOnly GPT-5 Nano measured
LMArena Text: hard prompts13281453Kimi K2.5
LMArena Text: expert13211466Kimi K2.5
LMArena Text: hard prompts in English13381460Kimi K2.5
LMArena Vision: diagrams11411282Kimi K2.5
LMArena Vision: homework11571297Kimi K2.5
Kagi LLM Benchmark62.2%78.5%Kimi 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 Nano and Kimi K2.5
BenchmarkGPT-5 NanoKimi K2.5Leader
AIME81.2%95.6%Kimi K2.5
MATH 500 (Vals AI)93.8%Not measuredOnly GPT-5 Nano measured
MGSM (Vals AI)89.3%Not measuredOnly GPT-5 Nano measured
AA Math Index83.7Not measuredOnly GPT-5 Nano measured
AIME 2025 (Artificial Analysis run)83.7%Not measuredOnly GPT-5 Nano measured
OTIS Mock AIME81.1%Not measuredOnly GPT-5 Nano measured
FrontierMath, tiers 1 to 320.0%Not measuredOnly GPT-5 Nano measured
FrontierMath, tier 42.4%Not measuredOnly GPT-5 Nano measured
ProofBench12.0%Not measuredOnly GPT-5 Nano measured
MATH level 595.2%Not measuredOnly GPT-5 Nano measured
LMArena Text: math13171470Kimi K2.5
LMArena Text: mathematical work13261473Kimi K2.5
Neither model has a result on the other 1 board here
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index011
Knowledge benchmarks for GPT-5 Nano and Kimi K2.5
BenchmarkGPT-5 NanoKimi K2.5Leader
MMLU Pro76.1%85.9%Kimi K2.5
LegalBench (Vals AI)50.1%Not measuredOnly GPT-5 Nano measured
CaseLaw (Vals AI)52.6%58.7%Kimi K2.5
CorpFin (Vals AI)Not measured68.3%Only Kimi K2.5 measured
TaxEval (Vals AI)67.4%74.2%Kimi K2.5
MortgageTax (Vals AI)53.6%66.5%Kimi K2.5
MedQA (Vals AI)93.3%94.4%Kimi K2.5
MedCode (Vals AI)30.4%39.3%Kimi K2.5
MMLU Pro (Artificial Analysis run)78.0%Not measuredOnly GPT-5 Nano measured
SimpleQA Verified11.7%34.3%Kimi K2.5
LMArena Text: science13181459Kimi K2.5
LMArena Text: medicine and healthcare13351448Kimi K2.5
LMArena Text: legal and government12981441Kimi K2.5
LMArena Text: business and finance13111427Kimi K2.5
Neither model has a result on the other 4 boards here
Web designLike-for-likePublic boards, shown as published, kept out of the index06
Web design benchmarks for GPT-5 Nano and Kimi K2.5
BenchmarkGPT-5 NanoKimi K2.5Leader
Design Arena: websites11011248Kimi K2.5
Design Arena: UI components10641234Kimi K2.5
Design Arena: game dev10441206Kimi K2.5
Design Arena: data viz10561219Kimi K2.5
Design Arena: 3D9651204Kimi K2.5
Design Arena: all code categories10841236Kimi K2.5
Design Arena: SVGNot measured1149Only Kimi K2.5 measured
Design Arena: ASCII artNot measured1166Only Kimi K2.5 measured
Neither model has a result on the other 1 board here
GeneralLike-for-likePublic boards, shown as published, kept out of the index026
General benchmarks for GPT-5 Nano and Kimi K2.5
BenchmarkGPT-5 NanoKimi K2.5Leader
SAGE (Vals AI)30.4%49.9%Kimi K2.5
MedScribe (Vals AI)72.9%76.4%Kimi K2.5
IFBench67.6%70.2%Kimi K2.5
Long context reasoning (AA-LCR)45.0%78.0%Kimi K2.5
DTBench62.7%Not measuredOnly GPT-5 Nano measured
LMCA7.9%Not measuredOnly GPT-5 Nano measured
Fiction.LiveBench44.4%86.1%Kimi K2.5
CL-benchNot measured19.3%Only Kimi K2.5 measured
CL-bench LifeNot measured13.2%Only Kimi K2.5 measured
LMArena Text13201445Kimi K2.5
LMArena Text: instruction following13061431Kimi K2.5
LMArena Text: creative writing12491422Kimi K2.5
LMArena Vision11591269Kimi K2.5
LMArena Text: English13211453Kimi K2.5
LMArena Text: non-English13131433Kimi K2.5
LMArena Text: Chinese13561494Kimi K2.5
LMArena Text: German13271441Kimi K2.5
LMArena Text: Japanese12271423Kimi K2.5
LMArena Text: Korean12691412Kimi K2.5
LMArena Text: FrenchNot measured1454Only Kimi K2.5 measured
LMArena Text: Spanish13601450Kimi K2.5
LMArena Text: Russian12961435Kimi K2.5
LMArena Text: Polish13141445Kimi K2.5
LMArena Text: multi-turn13111444Kimi K2.5
LMArena Text: longer queries13121445Kimi K2.5
LMArena Text: writing and language12831425Kimi K2.5
LMArena Text: entertainment and media12681417Kimi K2.5
LMArena Vision: English11701274Kimi K2.5
LMArena Vision: Chinese11761328Kimi K2.5
LMArena Vision: reading text11521276Kimi K2.5
LMArena Vision: humor11101284Kimi K2.5
LMArena Vision: captioningNot measured1257Only Kimi K2.5 measured
LMArena Vision: recognizing thingsNot measured1285Only Kimi K2.5 measured
LMArena Vision: creative writingNot measured1269Only Kimi K2.5 measured
Neither model has a result on the other 12 boards here
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
Image generation benchmarks for GPT-5 Nano and Kimi K2.5
BenchmarkGPT-5 NanoKimi 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 Nano$0.0003Fits in one request
Kimi K2.5$0.0020Fits in one request

GPT-5 Nano costs less

Repository review

50K input + 3K output tokens

GPT-5 Nano$0.0037Fits in one request
Kimi K2.5$0.035Fits in one request

GPT-5 Nano costs less

Agent loop

200K input + 10K output tokens

GPT-5 Nano$0.014Fits in one request
Kimi K2.5$0.135Fits in one request

GPT-5 Nano 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 Nano and Kimi K2.5
SpecificationOpenAI GPT-5 NanoMoonshotAI Kimi K2.5
MakerOpenAIMoonshot AI
WeightsNo public weights listedOpen weights
ReleasedAugust 7, 2025January 27, 2026
Context window400K262K
Input $/Mtok$0.05$0.532
Output $/Mtok$0.40$2.85
Coding indexNot benchmarked38.6
Independent measurements behind it03
Cost per solved task$0.109$0.24
SourceOpenRouter listingOpenRouter listing

Questions

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

Only Kimi K2.5 has a coding score, 38.6 on the Vibe Coding Index; GPT-5 Nano has none, so the two cannot be ranked on coding. Pick GPT-5 Nano for output tokens 7.1x cheaper ($0.40 vs $2.85 per million) and a lower cost per solved task ($0.109 against $0.24).

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

GPT-5 Nano costs $0.05 per million input tokens and $0.40 per million output tokens; Kimi K2.5 costs $0.532 and $2.85. Per solved SWE-bench Verified task, GPT-5 Nano costs $0.109 and Kimi K2.5 $0.24.

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

GPT-5 Nano, with 400K tokens against 262K.

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

68 benchmarks have a result for both models as of October 22, 2026. GPT-5 Nano's coding index rests on 0 independent benchmarks and Kimi K2.5's on 3. Where only one model has a result, the page says so instead of naming a winner.

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