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Model comparison

GPT-5.1 vs Kimi K2.5

Data verified

Head-to-head evidence from 20 shared benchmark results across 7 categories. Overall scores shown here use the public BenchAlign v5 ranking lane.

GPT-5.1
OpenAI
53.65/100
Margin
6.0pts
winning →
Kimi K2.5
Moonshot AI
59.66/100
0 category wins1 category wins

Public leaderboard positions: GPT-5.1 #94 (Estimated); Kimi K2.5 #54 (Supported). Intervals and evidence labels describe ranking uncertainty, not a guarantee for a specific workload.

Evidence parity. GPT-5.1 and Kimi K2.5 share 20 comparable benchmark results. 1 of 8 categories are comparable. 1 result is unique to GPT-5.1; 43 to Kimi K2.5.

Updated July 20, 2026
Shared results
20
GPT-5.1 only
1
Kimi K2.5 only
43
Comparable categories
1 / 8

Pick Kimi K2.5 if you want the stronger benchmark profile. GPT-5.1 only becomes the better choice if you want the stronger reasoning-first profile.

Confidence note. This is a partial-evidence comparison with 20 shared benchmark results across 7 evidence categories; 1 of 8 categories currently have scoreable aggregates for both models. Treat the verdict as directional until coverage is more balanced.

Why this result

Kimi K2.5 is clearly ahead on the BenchAlign aggregate, 59.66 to 53.65. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.

Kimi K2.5's sharpest advantage is in mathematics, where it averages 60.6 against 26.4. The single biggest benchmark swing on the page is FrontierMath v2 (Tier 4), 12.500% to 4.200%.

GPT-5.1 is also the more expensive model on tokens at $1.25 input / $10.00 output per 1M tokens, versus $0.60 input / $3.00 output per 1M tokens for Kimi K2.5. That is roughly 3.3x on output cost alone. GPT-5.1 is the reasoning model in the pair, while Kimi K2.5 is not. That usually helps on harder chain-of-thought-heavy tests, but it can also mean more latency and more token spend in real use. Kimi K2.5 gives you the larger context window at 256K, compared with 200K for GPT-5.1.

Category breakdown

Exact category averages are shown below. Not measured means BenchLM does not have enough sourced public coverage for that model and category.

Category scores and score margins for GPT-5.1 and Kimi K2.5
CategoryGPT-5.1ΔKimi K2.5
MathGPT-5.126.4Margin→ 34.2Kimi K2.560.6
AgenticGPT-5.1Not measuredMarginNo overlapKimi K2.555.0
CodingGPT-5.1Not measuredMarginNo overlapKimi K2.559.4
ReasoningGPT-5.1Not measuredMarginNo overlapKimi K2.561.0
KnowledgeGPT-5.1Not measuredMarginNo overlapKimi K2.556.9
MultilingualGPT-5.1Not measuredMarginNo overlapKimi K2.582.3
MultimodalGPT-5.1Not measuredMarginNo overlapKimi K2.578.5
Inst. FollowingGPT-5.1Not measuredMarginNo overlapKimi K2.593.9

Decisive benchmark drivers

The largest measured benchmark gaps in this matchup, with exact reported values.

More
A · GPT-5.1B · Kimi K2.5

  1. FrontierMath v2 (Tier 4)

    Math
    Source ↗
    A 12.500%B 4.200%
    Winner: GPT-5.1Δ 8.3
    FrontierMath v2 (Tier 4): GPT-5.1 scored 12.500%; Kimi K2.5 scored 4.200%. GPT-5.1 wins this benchmark.

  2. FrontierMath v2 (Tiers 1-3)

    Math
    Source ↗
    A 31.034%B 27.900%
    Winner: GPT-5.1Δ 3.1
    FrontierMath v2 (Tiers 1-3): GPT-5.1 scored 31.034%; Kimi K2.5 scored 27.900%. GPT-5.1 wins this benchmark.

Operational comparison

Runtime and commercial metrics are compared only when both models have a complete sourced value.

MetricGPT-5.1Kimi K2.5Comparison
Input / output priceUSD per 1M tokensGPT-5.1$1.25 input / $10 outputKimi K2.5$0.6 input / $3 outputKimi K2.5 has the lower combined listed price.
Generation speedtokens per secondGPT-5.1111 tok/sKimi K2.545 tok/sGPT-5.1 has the higher measured throughput.
First-answer latencyseconds to first tokenGPT-5.157.47 sKimi K2.52.38 sKimi K2.5 reaches the first token sooner.
Context windowmaximum listed tokensGPT-5.1200KKimi K2.5256KKimi K2.5 lists the larger context window.

Benchmark Deep Dive

Agentic
BenchmarkGPT-5.1Kimi K2.5Result
AA Agentic IndexSource 21.0%21.7%Kimi K2.5 leads
τ²-bench resultsSource 81.9%95.9%Kimi K2.5 leads
Gert LabsSource 41.24%45.88%Kimi K2.5 leads
GDPval-AASource 24.4%25.4%Kimi K2.5 leads
GDPval-AASource 9871009Kimi K2.5 leads
Terminal-Bench 2.0Source —50.8%Not comparable
BrowseCompSource —60.6%Not comparable
Claw-EvalSource —52.3%Not comparable
QwenClawBenchSource —54.3%Not comparable
τ³-bench resultsSource —65.7%Not comparable
DeepSearchQASource —77.1%Not comparable
DeepPlanningSource —14.4%Not comparable
ToolathlonSource —27.8%Not comparable
MCP AtlasSource —29.5%Not comparable
MCP-TasksSource —59.1%Not comparable
WideResearchSource —72.7%Not comparable
APEX-Agents-AASource —11.5%Not comparable
ResearchClawBenchSource —14.0%Not comparable
JobBenchSource —8.7%Not comparable
Coding
BenchmarkGPT-5.1Kimi K2.5Result
Vibe Code BenchSource 24.61%—Not comparable
AA Coding IndexSource 49.4%46.8%GPT-5.1 leads
AA-SciCodeSource 43.3%49.0%Kimi K2.5 leads
SWE-bench VerifiedSource —76.8%Not comparable
SWE-bench Verified*Source —70.8%Not comparable
LiveCodeBench v6Source —85.0%Not comparable
SWE-bench ProSource —50.7%Not comparable
SWE MultilingualSource —73%Not comparable
SWE-RebenchSource —58.5%Not comparable
React Native EvalsSource —77.2%Not comparable
SciCodeSource —48.7%Not comparable
Reasoning
BenchmarkGPT-5.1Kimi K2.5Result
AA-LCRSource 75.0%65.3%GPT-5.1 leads
CritPtSource 4.9%3.1%GPT-5.1 leads
LongBench v2Source —61%Not comparable
Knowledge
BenchmarkGPT-5.1Kimi K2.5Result
Artificial Analysis Intelligence IndexSource 36.9%35.4%GPT-5.1 leads
AA-GPQA DiamondSource 87.3%87.9%Kimi K2.5 leads
AA-HLESource 26.5%29.4%Kimi K2.5 leads
AA-Omniscience IndexSource 5.6%-8.1%GPT-5.1 leads
AA-Omniscience AccuracySource 37.6%34.3%GPT-5.1 leads
AA-Omniscience Hallucination RateSource 51.3%64.6%GPT-5.1 leads
GPQASource —87.6%Not comparable
GPQA-DSource —87.6%Not comparable
SuperGPQASource —69.2%Not comparable
MMLU-ProSource —87.1%Not comparable
MMLU-Pro (Arcee)Source —87.1%Not comparable
HLESource —30.1%Not comparable
MathKimi K2.5 wins
BenchmarkGPT-5.1Kimi K2.5Result
FrontierMath v2 (Tiers 1-3)Source 31.034%27.900%GPT-5.1 leads
FrontierMath v2 (Tier 4)Source 12.500%4.200%GPT-5.1 leads
AIME 2025Source —96.1%Not comparable
AIME26Source —95.8%Not comparable
AIME25 (Arcee)Source —96.3%Not comparable
HMMT Feb 2025Source —95.4%Not comparable
HMMT Nov 2025Source —91.1%Not comparable
HMMT Feb 2026Source —87.1%Not comparable
MMAnswerBenchSource —81.8%Not comparable
Multilingual
BenchmarkGPT-5.1Kimi K2.5Result
MMLU-ProXSource —82.3%Not comparable
NOVA-63Source —56.0%Not comparable
Multimodal
BenchmarkGPT-5.1Kimi K2.5Result
AA-MMMU-ProSource 75.5%75.4%GPT-5.1 leads
Design Arena WebsiteSource 12201282Kimi K2.5 leads
MMMU-ProSource —78.5%Not comparable
Video-MMESource —87.4%Not comparable
MMVUSource —80.4%Not comparable
VideoMMMUSource —86.6%Not comparable
Inst. Following
BenchmarkGPT-5.1Kimi K2.5Result
AA-IFBenchSource 72.9%70.2%GPT-5.1 leads
IFEvalSource —93.9%Not comparable
Frequently Asked Questions (2)

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

Kimi K2.5 is ahead on BenchLM's BenchAlign leaderboard, 59.66 to 53.65. The biggest single separator in this matchup is FrontierMath v2 (Tier 4), where the scores are 12.500% and 4.200%.

Which is better for math, GPT-5.1 or Kimi K2.5?

Kimi K2.5 has the edge for math in this comparison, averaging 60.6 versus 26.4. Inside this category, FrontierMath v2 (Tier 4) is the benchmark that creates the most daylight between them.

Self-host vs API cost

Estimates at 50,000 req/day · 1000 tokens/req average.

GPT-5.1
API / mo$8,438
Self-host / moNot listed
Break-even—
Proprietary model — self-hosting not applicable.
Kimi K2.5
API / mo$2,700
Self-host / mo$5,221
Break-even132M/day
Model the full break-even

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