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Claude Opus 5.5 vs Kimi K2.5

Full profiles: Claude Opus 5.5 (Anthropic) and Kimi K2.5 (Moonshot AI): every benchmark, price and rank.

Updated · Data from 13 sources

As of 29 Oct 2026, Claude Opus 5.5 is ahead of Kimi K2.5 on quality (69.2 vs 58.8 on the BenchLeader Index), but Kimi K2.5 is 6.7× cheaper at $1.20 vs $8.00 per 1M tokens blended. Claude Opus 5.5 leads in every category we measure both in.

Key facts (as of 29 Oct 2026)

  • Claude Opus 5.5 scores 69.2 on the BenchLeader Index and Kimi K2.5 scores 58.8 (BenchLeader, 29 Oct 2026).
  • Claude Opus 5.5 costs $8.00 per 1M tokens blended (list price, 29 Oct 2026).
  • Kimi K2.5 costs $1.20 per 1M tokens blended (list price, 29 Oct 2026).
  • Of the 6 benchmarks both models have, Claude Opus 5.5 leads 6 (BenchLeader, 29 Oct 2026).
  • On Arena WebDev, Claude Opus 5.5 is rated 1809 and Kimi K2.5 1437 (LMArena, as published by 29 Oct 2026).
Claude Opus 5.5 benchmarks max Anthropic Kimi K2.5 benchmarks thinking Moonshot AIOpen in the comparison tool

Which to pick for…

The pick's numbers come first. Category scores on the BenchLeader scale (50 is the average model, 15 points one standard deviation). High confidence means a lead of half a standard deviation or more; under one point is called either.

Use casePickWhyConfidence
CodingClaude Opus 5.580 vs 56 category score; Arena WebDev 1809 vs 1437High
Agents & tool useClaude Opus 5.563 vs 45 category scoreHigh
MathsClaude Opus 5.574 vs 56 category scoreHigh
ReasoningClaude Opus 5.573 vs 67 category score; Humanity's Last Exam (AA) 61.4% vs 30.7%Medium
KnowledgeClaude Opus 5.574 vs 60 category scoreHigh
Long documentsClaude Opus 5.567 vs 64 category score; AA-LCR v1.1 84.7% vs 78.0%Medium
Images and other mediaClaude Opus 5.571 vs 59 category score; MMMU-Pro 87.7% vs 75.4%High
Chat quality (human preference)–Only Kimi K2.5 has an Arena rating (63 category score)Not comparable
Lowest costKimi K2.5$1.20 vs $8.00 per 1M blended; agentic coding session $0.048 vs $0.320–
Fastest first answerKimi K2.536.0 s (Kimi K2.5 (thinking)) vs 648.2 s (Claude Opus 5.5 (max)) to the first answer token–
High volume on a budgetNeither flagshipA smaller model is usually the better fit: Cheapest good LLMs, Fastest LLMs–

Key differences

  • Claude Opus 5.5 (max) leads on quality: 69.2 vs 58.8.
  • Claude Opus 5.5 (max) is stronger in agents & tools, coding, knowledge, long context, maths, multimodal, reasoning.
  • Kimi K2.5 (thinking) is stronger in human preference, instruction following.
  • Kimi K2.5 (thinking) is 6.7× cheaper ($1.20 vs $8.00 per 1M blended).

At a glance

SpecClaude Opus 5.5Kimi K2.5
DeveloperAnthropicMoonshot AI
Released22 Sept 202627 Jan 2026
Context window (tokens)1,000,000262,144
Max output (tokens)128,000 (up to 300K on the Message Batches API (beta))–
Input typestext, image–
Reasoning effort settingslow, medium, high, xhigh, max–
Compared atClaude Opus 5.5 (max)Kimi K2.5 (thinking)
Open weightsNoYes
Price in / out / cached input per 1M$4.00 / $20.00 / $0.200$0.600 / $3.00 / $0.100
API model IDclaude-opus-5-5–
Where to use itClaude API, Amazon Bedrock, Google Cloud, Microsoft Foundry–

Limits, availability and announced prices from the vendors' own pages: docs.anthropic.com (checked 20 Oct 2026). Everything else is from the day's data.

Category by category

Category scores on the BenchLeader scale: 50 is the average evaluated model, 15 points is one standard deviation. A gap under one point is called level.

CategoryClaude Opus 5.5 (max)Kimi K2.5 (thinking)Leader
Reasoning72.967.3Claude Opus 5.5
Coding80.455.7Claude Opus 5.5
Agents & tools63.145.1Claude Opus 5.5
Maths74.056.2Claude Opus 5.5
Knowledge74.160.0Claude Opus 5.5
Instruction following–69.0not comparable
Human preference–63.4not comparable
Multimodal70.659.3Claude Opus 5.5
Long context67.363.8Claude Opus 5.5

Where sources disagree

Across the 6 benchmarks both have, Claude Opus 5.5 leads 6, Kimi K2.5 leads 0. Every overall index that rates both puts Claude Opus 5.5 ahead.

Overall indexClaude Opus 5.5 (max)Kimi K2.5 (thinking)Leader
BenchLeader Index69.258.8Claude Opus 5.5
Arena Text1509†1450Claude Opus 5.5

Each publisher runs its own tasks, harnesses and effort settings, so their overall verdicts can differ; BenchLeader reconciles them on one scale. † measured at another effort setting of the same model (the publisher did not test the one compared here).

Price, speed and latency

List prices blended at three input tokens per output token. Per-task prices use the token counts on the methodology page; suite cost is what Artificial Analysis paid to run its whole Intelligence Index.

MeasureClaude Opus 5.5 (max)Kimi K2.5 (thinking)
Blended price per 1M tokens$8.00$1.20
Input / output per 1M$4.00 / $20.00$0.600 / $3.00
Cached input per 1M$0.200$0.100
Price per task: chat reply$0.0076$0.0011
Price per task: summarize a 30-page report$0.060$0.0090
Price per task: code edit$0.054$0.0081
Price per task: agentic coding session$0.320$0.048
Price per task: structured extraction$0.012$0.0018
Cost to run a full benchmark suite$10.04–
Output speed98 tok/s87 tok/s
Time to first answer648.2 s36.0 s
Time to a complete answer653.3 s41.7 s

Each model is compared at its best-ranked reasoning-effort setting. Claude Opus 5.5 (max) scores 69.2 and takes 648 s to its first answer token; Claude Opus 5.5 (xhigh) scores 66.0 in 107 s, Claude Opus 5.5 (high) scores 65.6 in 34 s. Kimi K2.5 (thinking) scores 58.8 and takes 36 s to its first answer token; Kimi K2.5 scores 54.3 in 1 s. Higher effort means more thinking before the answer: better scores, longer waits and more tokens billed. How reasoning effort changes scores and cost.

Every benchmark

171 benchmarks, grouped by category; each name links to the board and its leaders. † measured at another effort setting of the same model, shown for reference and not counted as a win.

MetricPublisherClaude Opus 5.5 (max)Kimi K2.5 (thinking)
BenchLeader IndexBenchLeader69.258.8
Agents & tools scoreBenchLeader63.145.1
Coding scoreBenchLeader80.455.7
Knowledge scoreBenchLeader74.160.0
Long context scoreBenchLeader67.363.8
Maths scoreBenchLeader74.056.2
Multimodal scoreBenchLeader70.659.3
Reasoning scoreBenchLeader72.967.3
Human preference scoreBenchLeader–63.4
Instruction following scoreBenchLeader–69.0
Blended price $/MBenchLeader$8.00$1.20
Output speedBenchLeader98 tok/s87 tok/s
Time to first answerBenchLeader648.2 s36.0 s
Context windowBenchLeader1,000,000 tokens262,144 tokens
Reasoning
GPQA DiamondEpoch AI Benchmarking Hub90.6%87.6%†
Humanity's Last ExamScale AI / CAIS–24.4%†
SimpleBenchSimpleBench–46.8%†
Arena Hard PromptsArena (LMArena)1535†1471
LiveBench 2.0 ReasoningLiveBench92.2%†–
LiveBench 1.0 ReasoningLiveBench92.2%–
GPQA Diamond (AA)Artificial Analysis–87.9%
Humanity's Last Exam (AA)Artificial Analysis61.4%30.7%
HLE-Diamond (AA)Artificial Analysis67.9%–
GPQA Diamond (Vals)Vals AI–84.1%
Kagi LLM BenchmarkKagi LLM Benchmark–78.5%
ARC-AGI-1ARC Prize97.5%65.3%†
ARC-AGI-2ARC Prize91.7%11.8%†
CritPtArtificial Analysis31.7%3.1%
CritPt v2 hard subset (AA)Artificial Analysis61.0%–
MysteryMechanismVals AI49.5%†–
Chess PuzzlesEpoch AI Benchmarking Hub67.0%–
Mystery Game PuzzlesEpoch AI Benchmarking Hub71.0%–
CL-benchEpoch AI Benchmarking Hub–19.3%†
CL-bench LifeEpoch AI Benchmarking Hub–13.2%†
LMCAEpoch AI Benchmarking Hub68.2%–
DTBenchEpoch AI Benchmarking Hub98.9%–
Coding
SWE-bench Verified (Epoch)Epoch AI Benchmarking Hub–73.8%†
SciCodeSciCode66.9%49.0%†
WeirdMLWeirdML–45.6%†
Show all 171 benchmarks
MetricPublisherClaude Opus 5.5 (max)Kimi K2.5 (thinking)
Coding
FrontierCodeCognition54.6%†–
Arena CodingArena (LMArena)1548†1502
Arena WebDevArena (LMArena)18091437
LiveBench 2.0 CodingLiveBench96.3%†–
LiveBench 1.0 CodingLiveBench89.3%–
SciCode (AA)Artificial Analysis66.9%–
LiveCodeBenchVals AI–83.9%
IOIVals AI95.1%†–
SWE-bench (Vals)Vals AI–70.0%
SWE-bench Verified (bash only)SWE-bench–70.8%†
SWE-bench Verified (any scaffold)SWE-bench–70.8%†
Code MigrationVals AI66.7%†7.0%
Code Migration v1.1Vals AI81.0%†–
ProgramBenchVals AI18.5%†–
SWE-bench MultimodalVals AI70.2%†–
Vibe Code Bench 1-100Vals AI30.4%†–
Vibe Code Bench v1.1Vals AI90.3%†17.5%
SWE Atlas: Codebase QnAScale AI SEAL–13.1%†
SWE Atlas: RefactoringScale AI SEAL–20.9%†
SWE Atlas: Test WritingScale AI SEAL–25.8%†
MirrorCodeEpoch AI Benchmarking Hub77.4%–
CursorBenchCursor57.8%–
ALE-BenchEpoch AI Benchmarking Hub2147.4†821.6†
FrontierSWEEpoch AI Benchmarking Hub62.3%–
Terminal-Bench 4.0 (AA)Artificial Analysis59.6%–
Terminal-Bench 2.1 (AA)Artificial Analysis–45.7%
Startrise FrontendStartrise71.1%†–
FrontierCode 1.1 (AA)Artificial Analysis52.2%–
FrontierCode 2.0 (AA)Artificial Analysis46.4%–
Agents & tools
Terminal-BenchTerminal-Bench64.8%43.2%†
Remote Labor IndexScale AI / CAIS21.3%†–
APEX-AgentsMercor73.5%–
Arena AgentArena (LMArena)20.8–
LiveBench Long AgenticLiveBench72.8%†–
LiveBench BrowserLiveBench88.4%†–
LiveBench Agentic CodingLiveBench71.7%–
Terminal-Bench HardArtificial Analysis–34.9%
τ²-Bench Telecom (AA)Artificial Analysis–95.9%
Terminal-Bench 2.1 (Vals)Vals AI87.6%†42.0%
MCP AtlasScale AI SEAL–64.4%†
HiL-BenchScale AI SEAL59.0%†–
GDPval-AA v2.1, normalised scoreArtificial Analysis68.3%–
GDPval-AA v2.1Artificial Analysis1866–
τ³-Banking (AA)Artificial Analysis–14.2%
ITBench SRE (AA)Artificial Analysis38.2%–
Analyst Agent (AA)Artificial Analysis56.3%–
APEX-Agents (AA)Artificial Analysis–11.5%
CUA-benchVals AI14.0%–
CyberBenchVals AI55.4%†–
Finance Agent v2Vals AI58.6%†35.8%
Finance Agent v2.1Vals AI67.8%†–
Harvey's Legal Agent Benchmark v1.1Vals AI9.2%†–
Harvey's Legal Agent Benchmark v1Vals AI3.8%†0.0%
Legal Research BenchVals AI50.5%†15.9%
Robo-benchVals AI14.6%–
SREBenchVals AI33.6%†–
Tax Agent BenchVals AI45.6%†–
Terminal-Bench 2.0 (Vals)Vals AI–40.5%
Terminal-Bench 4.0 (Vals)Vals AI65.2%†–
Terminal-Bench ScienceVals AI47.1%†–
Time Horizon Index: KSPVals AI91.3%†–
Arena SearchArena (LMArena)1211†–
Vending-Bench 2Andon Labs9235.3†1198.5†
AutomationBenchArtificial Analysis69.5%–
GDP.pdf (AA)Artificial Analysis26.2%–
Harvey LAB-AA v1.1Harvey4.2%–
AA-Briefcase v1.1Artificial Analysis1800–
Terminal-Bench-Science 0.1 (AA)Artificial Analysis59.0%–
CWE-Bench (AA)Artificial Analysis58.3%–
DeepSec-Bench (AA)Artificial Analysis26.9%–
CyberGym end-to-end (AA)Artificial Analysis0.8%–
FACTS SearchGoogle86.5%†–
Maths
FrontierMath Tiers 1–3Epoch AI Benchmarking Hub91.2%–
FrontierMath Tier 4Epoch AI Benchmarking Hub95.0%–
OTIS Mock AIMEEpoch AI Benchmarking Hub100.0%92.2%†
ProofBenchVals AI100.0%–
LiveBench MathematicsLiveBench97.1%–
AIME (Vals)Vals AI–95.6%
AIME 2026MathArena–95.8%
HMMT February 2026MathArena–87.1%
MathArena ApexMathArena–8.8%
Arena MathsArena (LMArena)1512†1471
Knowledge
SimpleQA VerifiedEpoch AI Benchmarking Hub72.2%34.3%†
LiveBench 2.0 Data AnalysisLiveBench80.3%†–
LiveBench ResearchLiveBench85.0%†–
LiveBench 1.0 Data AnalysisLiveBench80.3%–
AA-Omniscience v1.1Artificial Analysis48.1–
MMLU-ProVals AI–85.9%
CorpFinVals AI–68.3%
TaxEvalVals AI–74.2%
MedQAVals AI–94.4%
PRBench FinanceScale AI SEAL–46.5%†
PRBench LegalScale AI SEAL47.6%†43.8%†
MultiNRCScale AI SEAL–35.2%†
BioMysteryBenchVals AI79.3%†–
CaseLaw v2Vals AI–58.7%
ClaimBenchVals AI100.0%†–
Excel Modeling BenchmarkVals AI75.9%†28.5%
Excel Modeling Benchmark v1.1Vals AI75.8%†–
MedCodeVals AI49.8%†39.3%
MedScribeVals AI91.4%†76.4%
Public Benefits Bench v1.1Vals AI70.6%†–
EBR-benchEpoch AI Benchmarking Hub71.4%–
GDP.pdfEpoch AI Benchmarking Hub30.6%–
AA-Omniscience v1.1: accuracyArtificial Analysis65.5%–
AA-Omniscience v1.1: non-hallucinationArtificial Analysis49.7%–
HealthBench Professional (AA)OpenAI59.9%–
Instruction following
LiveBench LanguageLiveBench86.3%–
LiveBench Instruction FollowingLiveBench65.7%–
IFBenchArtificial Analysis–70.2%
MultiChallengeScale AI SEAL–61.4%†
TutorBenchScale AI SEAL–54.6%†
Arena Instruction FollowingArena (LMArena)1521†1439
Human preference
Arena TextArena (LMArena)1509†1450
EQ-Bench 4EQ-Bench1340†–
Arena Creative WritingArena (LMArena)1520†1423
Arena Multi-turnArena (LMArena)1503†1452
Arena Longer QueriesArena (LMArena)1524†1458
Multimodal
Arena VisionArena (LMArena)1321†1269
LiveBench DesignLiveBench86.9%†–
MMMU-ProArtificial Analysis87.7%75.4%
VISTAScale AI SEAL–41.9%†
MMMU-Pro (Vals)Vals AI–84.3%
MortgageTaxVals AI–66.5%
SAGEVals AI91.3%†–
Blueprint-Bench 2Epoch AI Benchmarking Hub51.2%†–
Code2Video-AAArtificial Analysis1536–
AA-3DArtificial Analysis1196–
Long context
Fiction.LiveBench 120kFiction.live–78.1%†
AA-LCR v1.1Artificial Analysis84.7%78.0%
Arena DocumentArena (LMArena)–1436
MLCRArtificial Analysis27.8%–
Composite
Epoch Capabilities IndexEpoch AI Benchmarking Hub168.8†148.1†
LiveBench 2.0LiveBench85.1%†–
LiveBench 1.0LiveBench83.2%–
AA Intelligence Index v5.0Artificial Analysis58.4–
AA Intelligence Index v4.3.2Artificial Analysis57.623.5
AA Progress Index v1Artificial Analysis350270.5
Vals IndexVals AI70.2†–
Vals Finance IndexVals AI65.6%†–
Vals RSI IndexVals AI37.3%6.8%†
Vals Science IndexVals AI58.6%†–
Vals Router IndexVals AI64.2%†–
AA Cyber IndexArtificial Analysis28.7–
Safety & honesty
FORTRESSScale AI SEAL5.8%41.1%†
MASKScale AI SEAL–70.5%†

Data as of 2026-10-29. Best configuration of each model; every score links to its source on the model pages.

What changed

  • Claude Opus 5.5 (max): 5 new results (AA Intelligence Index v5.0, AA Progress Index v1, HLE-Diamond (AA)…); 3 score revisions; cost per task moved from $5.98/M to $10.04/M (68% up).
  • Kimi K2.5 (thinking): 1 new result (AA Progress Index v1).
  • Claude Opus 5.5 (max): 1 score revision.
  • Claude Opus 5.5 (max): 2 new results (Robo-bench, Vals RSI Index).
  • Kimi K2.5 (thinking): 1 new result (Harvey's Legal Agent Benchmark v1).
  • Claude Opus 5.5 (max): 2 score revisions.
  • Kimi K2.5 (thinking): output price moved from $2.75/M to $3.00/M (9% up).
  • Claude Opus 5.5 (max): 2 score revisions.
  • Claude Opus 5.5 (max): 1 new result (FORTRESS).
  • Claude Opus 5.5 (max): 1 score revision.

Rankings: Best LLM overall · Best LLM for coding · Best LLM for agents · Best cheap LLMs

Claude Opus 5.5 vs Kimi K2.5: questions

Is Claude Opus 5.5 better than Kimi K2.5?
Claude Opus 5.5 (max) leads on quality: 69.2 vs 58.8. The BenchLeader Index combines every independent quality benchmark; Claude Opus 5.5 (max) is ahead overall as of 29 Oct 2026, but check the category scores for your use.
Claude Opus 5.5 vs Kimi K2.5: which is cheaper, and will that change?
Kimi K2.5 is cheaper today: $1.20 against $8.00 per million tokens, blended at three input tokens per output token. No price change has been announced for either.
Is Claude Opus 5.5 or Kimi K2.5 better for coding?
Claude Opus 5.5 scores higher in coding (80 vs 56 on the category index, where 50 is average). On Arena WebDev, the top shared coding benchmark, it is 1809 for Claude Opus 5.5 against 1437 for Kimi K2.5.
Which is faster, Claude Opus 5.5 or Kimi K2.5?
Claude Opus 5.5 streams faster (98 vs 87 output tokens per second, Artificial Analysis 7-day median).
Is Claude Opus 5.5 or Kimi K2.5 better for agents and tool use?
Claude Opus 5.5 scores higher in agentic tasks (63 vs 45 on the category index, where 50 is average).
More questions (4)
Which is better for long documents?
Claude Opus 5.5 scores higher on long-context benchmarks (67 vs 64). Claude Opus 5.5 accepts more context: 1,000,000 against 262,144 tokens for Kimi K2.5.
Which has lower latency?
Kimi K2.5 answers first: 36.0 s against 648.2 s to the first answer token, as Artificial Analysis measures it. Reasoning effort drives most of this: a higher setting thinks longer before it answers.
Do independent benchmarks agree on Claude Opus 5.5 vs Kimi K2.5?
Across the 6 benchmarks both have, Claude Opus 5.5 leads 6, Kimi K2.5 leads 0. Every overall index that rates both puts Claude Opus 5.5 ahead.
When was Claude Opus 5.5 released?
Claude Opus 5.5 was released on 22 Sept 2026.