Noometry

Model comparison

Claude Opus 4.8 vs Kimi K2 (Jul 2025)

Claude Opus 4.8 is the stronger model overall, scoring 60.7 to 41.2 on the Noometry Index. Kimi K2 (Jul 2025) costs 10.0× less per token, which makes it the better buy when Claude Opus 4.8's lead doesn't matter for your workload.

Last verified . 27 shared benchmarks.

Claude Opus 4.8 Anthropic

60.7

Rank #13 Confirmed

Kimi K2 (Jul 2025) Moonshot AI

41.2

Rank #140 Confirmed

Summary

  • They share 27 benchmarks with published results for both. Claude Opus 4.8 scores higher in 9 categories and Kimi K2 (Jul 2025) in 0 categories; 9 gaps are clear of the uncertainty.
  • The widest gap is in reasoning, where Claude Opus 4.8 leads 64.7 to 23.3.
  • The biggest single-benchmark swing is GSO: 47.1% for Claude Opus 4.8 and 4.9% for Kimi K2 (Jul 2025).
  • Kimi K2 (Jul 2025) is cheaper at $0.57 / $2.30 per million input/output tokens, against $5 / $25 for Claude Opus 4.8.
  • Claude Opus 4.8 accepts more context: 1M tokens versus 262K.
  • Kimi K2 (Jul 2025) has downloadable open weights; the other is API-only.

Side by side

Claude Opus 4.8Kimi K2 (Jul 2025)
ProviderAnthropicMoonshot AI
Noometry Index60.741.2
Released2026-05-282025-07-12
WeightsProprietaryOpen
Context window1M262K
Max output128K262K
Input $ / M tokens$5$0.57
Output $ / M tokens$25$2.30
Results tracked6542

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Category by category

Coding Claude Opus 4.8 leads

Claude Opus 4.8: 59.9 (#12), Kimi K2 (Jul 2025): 42.4 (#102)

BenchmarkClaude Opus 4.8Kimi K2 (Jul 2025)
GSO47.1%4.9%
WeirdML82.9%42.8%
LMArena Coding14901399
ALE-Bench1,564597.5
DeepSWE59%—
FrontierCode46.5%—
SWE-bench Verified (bash only)—63.4%
Aider Polyglot—59.1%
LMArena WebDev1556—
SciCode53.5%—

Agentic & Tool Use Claude Opus 4.8 leads

Claude Opus 4.8: 47.6 (#11), Kimi K2 (Jul 2025): 32.4 (#64)

BenchmarkClaude Opus 4.8Kimi K2 (Jul 2025)
Terminal-Bench—35.7%
APEX-Agents48.9%—
Berkeley Function Calling Leaderboard—59.1%
OSWorld 2.020.6%—
Remote Labor Index8.3%—
τ²-bench Banking39.7%—
DeepResearch Bench50.2%—
PostTrainBench33.8%—
GBAEval70.9%—
GDP.pdf24%—
LMArena Search1204—
METR Time Horizons—59.2%
Vending-Bench 25,787—

Reasoning Claude Opus 4.8 leads

Claude Opus 4.8: 64.7 (#16), Kimi K2 (Jul 2025): 23.3 (#179)

BenchmarkClaude Opus 4.8Kimi K2 (Jul 2025)
SimpleBench64.8%26.3%
Kagi LLM Benchmark88.8%64.4%
LMArena Hard Prompts14821384
Epoch Capabilities Index158.21146.01
ForecastBench59.960.2
ARC-AGI-272.1%—
NYT Connections (extended)91.1%—
ARC-AGI-192.5%—
CritPt20.9%—
Chess Puzzles34%—
EnigmaEval23.5%—
EBR-Bench28.6%—
Mystery Game Puzzles36%—
DTBench94.9%—
LMCA57.5%—
Surface Evolver Bench87.5%—
Bench to the Future 30.14—

Math Claude Opus 4.8 leads

Claude Opus 4.8: 78.4 (#13), Kimi K2 (Jul 2025): 42.7 (#83)

BenchmarkClaude Opus 4.8Kimi K2 (Jul 2025)
LMArena Math14871397
FrontierMath (Feb 2025 set)47.2%21.4%
FrontierMath Tier 4 (v1)31.3%0%
FrontierMath (Tiers 1-3)80%—
FrontierMath Tier 456.1%—
MathArena Final-Answer Competitions91.8%—
OTIS Mock AIME 2024-202598.3%—
ProofBench69%—
Omni-MATH—65.4%

Knowledge Claude Opus 4.8 leads

Claude Opus 4.8: 61.3 (#29), Kimi K2 (Jul 2025): 37.3 (#157)

BenchmarkClaude Opus 4.8Kimi K2 (Jul 2025)
LMArena Expert15021365
GPQA Diamond91%—
SimpleQA Verified53%—
MMLU-Pro—81.9%
Confabulations—20.4%
Vectara Hallucination Rate—17.9%
GPQA (HELM)—65.3%

Multimodal Not comparable

Claude Opus 4.8: 42.9 (#26), Kimi K2 (Jul 2025): —

BenchmarkClaude Opus 4.8Kimi K2 (Jul 2025)
LMArena Vision1294—
Blueprint-Bench 214.5%—
Furniture Assembly42.5%—
LMArena Document1475—

Multilingual Claude Opus 4.8 leads

Claude Opus 4.8: 55.2 (#33), Kimi K2 (Jul 2025): 49.6 (#130)

BenchmarkClaude Opus 4.8Kimi K2 (Jul 2025)
LMArena Non-English14501372
LMArena Chinese15071415
LMArena French14811379
LMArena German14721387
LMArena Japanese14401349
LMArena Korean14321325
LMArena Russian14741385
LMArena Spanish14661386

Instruction Following Claude Opus 4.8 leads

Claude Opus 4.8: 77.4 (#24), Kimi K2 (Jul 2025): 71.1 (#156)

BenchmarkClaude Opus 4.8Kimi K2 (Jul 2025)
LMArena Instruction Following14761348
IFEval—85%

Long Context Claude Opus 4.8 leads

Claude Opus 4.8: 45.4 (#35), Kimi K2 (Jul 2025): 41.2 (#145)

BenchmarkClaude Opus 4.8Kimi K2 (Jul 2025)
LMArena Longer Query14831353
Fiction.LiveBench—66.7%
CL-bench—17.6%

Writing & Preference Claude Opus 4.8 leads

Claude Opus 4.8: 72.0 (#16), Kimi K2 (Jul 2025): 62.3 (#78)

BenchmarkClaude Opus 4.8Kimi K2 (Jul 2025)
LMArena Text14611380
LMArena Creative Writing14541350
EQ-Bench Creative Writing18401666
LMArena Multi-Turn14761371
Short-Story Creative Writing—85.6%
WildBench—86.2%
EQ-Bench 41281—

Frequently asked questions

Is Claude Opus 4.8 better than Kimi K2 (Jul 2025)?

Claude Opus 4.8 is the stronger model overall, scoring 60.7 to 41.2 on the Noometry Index. Kimi K2 (Jul 2025) costs 10.0× less per token, which makes it the better buy when Claude Opus 4.8's lead doesn't matter for your workload.

Which is cheaper, Claude Opus 4.8 or Kimi K2 (Jul 2025)?

Kimi K2 (Jul 2025) is cheaper. It lists at $0.57 per million input tokens and $2.30 per million output tokens; Claude Opus 4.8 lists at $5 and $25.

Is Claude Opus 4.8 or Kimi K2 (Jul 2025) better for coding?

Claude Opus 4.8 scores higher on coding benchmarks: 59.9 versus 42.4 in the Noometry coding category.

Which has the bigger context window?

Claude Opus 4.8 does, with 1M tokens against 262K.

How many benchmarks do Claude Opus 4.8 and Kimi K2 (Jul 2025) share?

27 benchmarks have published results for both models. Claude Opus 4.8 has 65 scored results on Noometry and Kimi K2 (Jul 2025) has 42.

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