Model comparison
Claude Opus 4.8 vs Kimi K2.5 (Reasoning)
Head-to-head evidence from 21 shared benchmark results across 6 categories. Overall scores shown here use the public BenchAlign v5 ranking lane.
Public leaderboard positions: Claude Opus 4.8 #5 (Supported); Kimi K2.5 (Reasoning) #57 (Estimated). Intervals and evidence labels describe ranking uncertainty, not a guarantee for a specific workload.
Evidence parity. Claude Opus 4.8 and Kimi K2.5 (Reasoning) share 21 comparable benchmark results. 4 of 8 categories are comparable. 32 results are unique to Claude Opus 4.8; 6 to Kimi K2.5 (Reasoning).
Updated July 23, 2026- Shared results
- 21
- Claude Opus 4.8 only
- 32
- Kimi K2.5 (Reasoning) only
- 6
- Comparable categories
- 4 / 8
Pick Claude Opus 4.8 if you want the stronger benchmark profile. Kimi K2.5 (Reasoning) only becomes the better choice if knowledge is the priority or you want the cheaper token bill.
Confidence note. This is a partial-evidence comparison with 21 shared benchmark results across 6 evidence categories; 4 of 8 categories currently have scoreable aggregates for both models. Treat the verdict as directional until coverage is more balanced.
Why this result
Claude Opus 4.8 is clearly ahead on the BenchAlign aggregate, 78.34 to 59.35. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.
Claude Opus 4.8's sharpest advantage is in agentic, where it averages 80.3 against 55. The single biggest benchmark swing on the page is Terminal-Bench 2.0, 74.6% to 50.8%. Kimi K2.5 (Reasoning) does hit back in knowledge, so the answer changes if that is the part of the workload you care about most.
Claude Opus 4.8 is also the more expensive model on tokens at $5.00 input / $25.00 output per 1M tokens, versus $0.60 input / $3.00 output per 1M tokens for Kimi K2.5 (Reasoning). That is roughly 8.3x on output cost alone. Claude Opus 4.8 gives you the larger context window at 1M, compared with 128K for Kimi K2.5 (Reasoning).
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 | Claude Opus 4.8 | Δ | Kimi K2.5 (Reasoning) |
|---|---|---|---|
| Agentic | Claude Opus 4.880.3 | Margin← 25.3 | Kimi K2.5 (Reasoning)55.0 |
| Knowledge | Claude Opus 4.862.7 | Margin→ 24.5 | Kimi K2.5 (Reasoning)87.2 |
| Coding | Claude Opus 4.881.1 | Margin← 4.3 | Kimi K2.5 (Reasoning)76.8 |
| Multimodal | Claude Opus 4.877.0 | Margin→ 1.5 | Kimi K2.5 (Reasoning)78.5 |
| Math | Claude Opus 4.853.9 | MarginNo overlap | Kimi K2.5 (Reasoning)Not measured |
Decisive benchmark drivers
The largest measured benchmark gaps in this matchup, with exact reported values.
More
- Source ↗
Terminal-Bench 2.0
AgenticA 74.6%B 50.8%Winner: Claude Opus 4.8Δ 23.8Terminal-Bench 2.0: Claude Opus 4.8 scored 74.6%; Kimi K2.5 (Reasoning) scored 50.8%. Claude Opus 4.8 wins this benchmark. - Source ↗
BrowseComp
AgenticA 84.3%B 60.6%Winner: Claude Opus 4.8Δ 23.7BrowseComp: Claude Opus 4.8 scored 84.3%; Kimi K2.5 (Reasoning) scored 60.6%. Claude Opus 4.8 wins this benchmark. - Source ↗
SWE-bench Verified
CodingA 88.6%B 76.8%Winner: Claude Opus 4.8Δ 11.8SWE-bench Verified: Claude Opus 4.8 scored 88.6%; Kimi K2.5 (Reasoning) scored 76.8%. Claude Opus 4.8 wins this benchmark. - Source ↗
GPQA
KnowledgeA 93.6%B 87.6%Winner: Claude Opus 4.8Δ 6GPQA: Claude Opus 4.8 scored 93.6%; Kimi K2.5 (Reasoning) scored 87.6%. Claude Opus 4.8 wins this benchmark.
Operational comparison
Runtime and commercial metrics are compared only when both models have a complete sourced value.
| Metric | Claude Opus 4.8 | Kimi K2.5 (Reasoning) | Comparison |
|---|---|---|---|
| Input / output priceUSD per 1M tokens | Claude Opus 4.8$5 input / $25 output | Kimi K2.5 (Reasoning)$0.6 input / $3 output | Kimi K2.5 (Reasoning) has the lower combined listed price. |
| Generation speedtokens per second | Claude Opus 4.8Not available | Kimi K2.5 (Reasoning)Not available | A complete speed comparison is not available. |
| First-answer latencyseconds to first token | Claude Opus 4.8Not available | Kimi K2.5 (Reasoning)Not available | A complete latency comparison is not available. |
| Context windowmaximum listed tokens | Claude Opus 4.81M | Kimi K2.5 (Reasoning)128K | Claude Opus 4.8 lists the larger context window. |
Benchmark Deep Dive
AgenticClaude Opus 4.8 wins22 benchmarks
| Benchmark | Claude Opus 4.8 | Kimi K2.5 (Reasoning) | Result |
|---|---|---|---|
| Terminal-Bench 2.0Source | 74.6% | 50.8% | Claude Opus 4.8 leads |
| BrowseCompSource | 84.3% | 60.6% | Claude Opus 4.8 leads |
| DeepSearchQASource | 93.1% | — | Not comparable |
| OSWorld-VerifiedSource | 83.4% | — | Not comparable |
| Finance Agent v2Source | 53.9% | — | Not comparable |
| GDPval-AASource | 1594 | 1009 | Claude Opus 4.8 leads |
| MCP AtlasSource | 82.2% | — | Not comparable |
| ToolathlonSource | 59.9% | — | Not comparable |
| Gert LabsSource | 72.97% | 32.58% | Claude Opus 4.8 leads |
| AA Agentic IndexSource | 47.2% | 21.7% | Claude Opus 4.8 leads |
| τ²-bench resultsSource | 94.4% | 95.9% | Kimi K2.5 (Reasoning) leads |
| GDPval-AASource | 54.7% | 25.4% | Claude Opus 4.8 leads |
| ResearchClawBenchSource | 21.1% | — | Not comparable |
| OSWorld 2.0Source | 20.6% | — | Not comparable |
| AA BriefcaseSource | 1347 | — | Not comparable |
| AA AutomationBenchSource | 48.5% | — | Not comparable |
| AA EnterpriseOps-GymSource | 44.0% | — | Not comparable |
| AA Harvey LABSource | 91.1% | — | Not comparable |
| AA Tau3 BankingSource | 27.6% | — | Not comparable |
| terminalBenchHardSource | 58.3% | — | Not comparable |
| aaTerminalBench21Source | 84.6% | — | Not comparable |
| APEX-Agents-AASource | — | 11.5% | Not comparable |
CodingClaude Opus 4.8 wins11 benchmarks
| Benchmark | Claude Opus 4.8 | Kimi K2.5 (Reasoning) | Result |
|---|---|---|---|
| SWE-bench VerifiedSource | 88.6% | 76.8% | Claude Opus 4.8 leads |
| SWE-bench ProSource | 69.2% | — | Not comparable |
| SWE MultilingualSource | 84.4% | — | Not comparable |
| SWE MultimodalSource | 38.4% | — | Not comparable |
| Terminal-Bench 2.0Source | 74.6% | — | Not comparable |
| cursorBench31Source | 58.4% | — | Not comparable |
| cursorBench32Source | 62.3% | — | Not comparable |
| AA Coding IndexSource | 74.3% | 46.8% | Claude Opus 4.8 leads |
| AA-SciCodeSource | 53.5% | 49.0% | Claude Opus 4.8 leads |
| FrontierCode 1.1 MainSource | 46.5% | — | Not comparable |
| Vibe Code BenchSource | — | 17.54% | Not comparable |
Reasoning2 benchmarks
KnowledgeKimi K2.5 (Reasoning) wins11 benchmarks
| Benchmark | Claude Opus 4.8 | Kimi K2.5 (Reasoning) | Result |
|---|---|---|---|
| GPQASource | 93.6% | 87.6% | Claude Opus 4.8 leads |
| GPQA-DSource | 93.6% | — | Not comparable |
| HLESource | 57.9% | — | Not comparable |
| HLE w/o toolsSource | 49.8% | — | Not comparable |
| Artificial Analysis Intelligence IndexSource | 55.7% | 35.4% | Claude Opus 4.8 leads |
| AA-GPQA DiamondSource | 92.0% | 87.9% | Claude Opus 4.8 leads |
| AA-HLESource | 45.7% | 29.4% | Claude Opus 4.8 leads |
| AA-Omniscience IndexSource | 27.4% | -8.1% | Claude Opus 4.8 leads |
| AA-Omniscience AccuracySource | 46.6% | 34.3% | Claude Opus 4.8 leads |
| AA-Omniscience Hallucination RateSource | 35.9% | 64.6% | Claude Opus 4.8 leads |
| MMLU-ProSource | — | 87.1% | Not comparable |
Math4 benchmarks
Multilingual1 benchmarks
| Benchmark | Claude Opus 4.8 | Kimi K2.5 (Reasoning) | Result |
|---|---|---|---|
| INCLUDESource | 87.6% | — | Not comparable |
MultimodalKimi K2.5 (Reasoning) wins7 benchmarks
| Benchmark | Claude Opus 4.8 | Kimi K2.5 (Reasoning) | Result |
|---|---|---|---|
| OfficeQA ProSource | 66.2% | — | Not comparable |
| ScreenSpot ProSource | 87.9% | — | Not comparable |
| CharXivSource | 89.9% | — | Not comparable |
| CharXiv w/o toolsSource | 80.5% | — | Not comparable |
| Design Arena WebsiteSource | 1270 | 1279 | Kimi K2.5 (Reasoning) leads |
| MMMU-ProSource | — | 78.5% | Not comparable |
| AA-MMMU-ProSource | — | 75.4% | Not comparable |
Inst. Following1 benchmarks
| Benchmark | Claude Opus 4.8 | Kimi K2.5 (Reasoning) | Result |
|---|---|---|---|
| AA-IFBenchSource | 62.2% | 70.2% | Kimi K2.5 (Reasoning) leads |
Frequently Asked Questions (5)
Which is better, Claude Opus 4.8 or Kimi K2.5 (Reasoning)?
Claude Opus 4.8 is ahead on BenchLM's BenchAlign leaderboard, 78.34 to 59.35. The biggest single separator in this matchup is Terminal-Bench 2.0, where the scores are 74.6% and 50.8%.
Which is better for knowledge tasks, Claude Opus 4.8 or Kimi K2.5 (Reasoning)?
Kimi K2.5 (Reasoning) has the edge for knowledge tasks in this comparison, averaging 87.2 versus 62.7. Inside this category, AA-Omniscience Index is the benchmark that creates the most daylight between them.
Which is better for coding, Claude Opus 4.8 or Kimi K2.5 (Reasoning)?
Claude Opus 4.8 has the edge for coding in this comparison, averaging 81.1 versus 76.8. Inside this category, AA Coding Index is the benchmark that creates the most daylight between them.
Which is better for agentic tasks, Claude Opus 4.8 or Kimi K2.5 (Reasoning)?
Claude Opus 4.8 has the edge for agentic tasks in this comparison, averaging 80.3 versus 55. Inside this category, GDPval-AA is the benchmark that creates the most daylight between them.
Which is better for multimodal and grounded tasks, Claude Opus 4.8 or Kimi K2.5 (Reasoning)?
Kimi K2.5 (Reasoning) has the edge for multimodal and grounded tasks in this comparison, averaging 78.5 versus 77. Inside this category, Design Arena Website is the benchmark that creates the most daylight between them.
Related Comparisons
Choose a model with this week’s evidence
Join 2,000+ readers for ranking moves, pricing changes, and the claims that still need proof.
One email each week. Unsubscribe anytime.