Model comparison
Claude 3.5 Sonnet vs Kimi K2.5 (Reasoning)
Head-to-head evidence from 2 shared benchmark results across 2 categories. Overall scores shown here use the public BenchAlign v5 ranking lane.
Public leaderboard positions: Claude 3.5 Sonnet #132 (Estimated); Kimi K2.5 (Reasoning) #57 (Estimated). Intervals and evidence labels describe ranking uncertainty, not a guarantee for a specific workload.
Evidence parity. Claude 3.5 Sonnet and Kimi K2.5 (Reasoning) share 2 comparable benchmark results. 2 of 8 categories are comparable. 2 results are unique to Claude 3.5 Sonnet; 25 to Kimi K2.5 (Reasoning).
Updated July 20, 2026- Shared results
- 2
- Claude 3.5 Sonnet only
- 2
- Kimi K2.5 (Reasoning) only
- 25
- Comparable categories
- 2 / 8
Pick Kimi K2.5 (Reasoning) if you want the stronger benchmark profile. Claude 3.5 Sonnet only becomes the better choice if you need the larger 200K context window or you would rather avoid the extra latency and token burn of a reasoning model.
Confidence note. This is a partial-evidence comparison with 2 shared benchmark results across 2 evidence categories; 2 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 (Reasoning) is clearly ahead on the BenchAlign aggregate, 59.35 to 47.74. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.
Kimi K2.5 (Reasoning)'s sharpest advantage is in knowledge, where it averages 87.2 against 59.4. The single biggest benchmark swing on the page is GPQA, 59.4% to 87.6%.
Claude 3.5 Sonnet is also the more expensive model on tokens at $3.00 input / $15.00 output per 1M tokens, versus $0.60 input / $3.00 output per 1M tokens for Kimi K2.5 (Reasoning). That is roughly 5.0x on output cost alone. Kimi K2.5 (Reasoning) is the reasoning model in the pair, while Claude 3.5 Sonnet 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. Claude 3.5 Sonnet gives you the larger context window at 200K, 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 3.5 Sonnet | Δ | Kimi K2.5 (Reasoning) |
|---|---|---|---|
| Knowledge | Claude 3.5 Sonnet59.4 | Margin→ 27.8 | Kimi K2.5 (Reasoning)87.2 |
| Coding | Claude 3.5 Sonnet49.0 | Margin→ 27.8 | Kimi K2.5 (Reasoning)76.8 |
| Agentic | Claude 3.5 SonnetNot measured | MarginNo overlap | Kimi K2.5 (Reasoning)55.0 |
| Math | Claude 3.5 Sonnet1.6 | MarginNo overlap | Kimi K2.5 (Reasoning)Not measured |
| Multimodal | Claude 3.5 SonnetNot measured | MarginNo overlap | Kimi K2.5 (Reasoning)78.5 |
Decisive benchmark drivers
The largest measured benchmark gaps in this matchup, with exact reported values.
More
- Source ↗
GPQA
KnowledgeA 59.4%B 87.6%Winner: Kimi K2.5 (Reasoning)Δ 28.2GPQA: Claude 3.5 Sonnet scored 59.4%; Kimi K2.5 (Reasoning) scored 87.6%. Kimi K2.5 (Reasoning) wins this benchmark. - Source ↗
SWE-bench Verified
CodingA 49%B 76.8%Winner: Kimi K2.5 (Reasoning)Δ 27.8SWE-bench Verified: Claude 3.5 Sonnet scored 49%; Kimi K2.5 (Reasoning) scored 76.8%. Kimi K2.5 (Reasoning) wins this benchmark.
Operational comparison
Runtime and commercial metrics are compared only when both models have a complete sourced value.
| Metric | Claude 3.5 Sonnet | Kimi K2.5 (Reasoning) | Comparison |
|---|---|---|---|
| Input / output priceUSD per 1M tokens | Claude 3.5 Sonnet$3 input / $15 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 3.5 SonnetNot available | Kimi K2.5 (Reasoning)Not available | A complete speed comparison is not available. |
| First-answer latencyseconds to first token | Claude 3.5 SonnetNot available | Kimi K2.5 (Reasoning)Not available | A complete latency comparison is not available. |
| Context windowmaximum listed tokens | Claude 3.5 Sonnet200K | Kimi K2.5 (Reasoning)128K | Claude 3.5 Sonnet lists the larger context window. |
Benchmark Deep Dive
Agentic8 benchmarks
| Benchmark | Claude 3.5 Sonnet | Kimi K2.5 (Reasoning) | Result |
|---|---|---|---|
| Terminal-Bench 2.0Source | — | 50.8% | Not comparable |
| BrowseCompSource | — | 60.6% | Not comparable |
| APEX-Agents-AASource | — | 11.5% | Not comparable |
| τ²-bench resultsSource | — | 95.9% | Not comparable |
| Gert LabsSource | — | 32.58% | Not comparable |
| AA Agentic IndexSource | — | 21.7% | Not comparable |
| GDPval-AASource | — | 25.4% | Not comparable |
| GDPval-AASource | — | 1009 | Not comparable |
CodingKimi K2.5 (Reasoning) wins4 benchmarks
Reasoning2 benchmarks
KnowledgeKimi K2.5 (Reasoning) wins8 benchmarks
| Benchmark | Claude 3.5 Sonnet | Kimi K2.5 (Reasoning) | Result |
|---|---|---|---|
| GPQASource | 59.4% | 87.6% | Kimi K2.5 (Reasoning) leads |
| MMLU-ProSource | — | 87.1% | Not comparable |
| Artificial Analysis Intelligence IndexSource | — | 35.4% | Not comparable |
| AA-GPQA DiamondSource | — | 87.9% | Not comparable |
| AA-HLESource | — | 29.4% | Not comparable |
| AA-Omniscience IndexSource | — | -8.1% | Not comparable |
| AA-Omniscience AccuracySource | — | 34.3% | Not comparable |
| AA-Omniscience Hallucination RateSource | — | 64.6% | Not comparable |
Math3 benchmarks
Multimodal3 benchmarks
Inst. Following1 benchmarks
| Benchmark | Claude 3.5 Sonnet | Kimi K2.5 (Reasoning) | Result |
|---|---|---|---|
| AA-IFBenchSource | — | 70.2% | Not comparable |
Frequently Asked Questions (3)
Which is better, Claude 3.5 Sonnet or Kimi K2.5 (Reasoning)?
Kimi K2.5 (Reasoning) is ahead on BenchLM's BenchAlign leaderboard, 59.35 to 47.74. The biggest single separator in this matchup is GPQA, where the scores are 59.4% and 87.6%.
Which is better for knowledge tasks, Claude 3.5 Sonnet or Kimi K2.5 (Reasoning)?
Kimi K2.5 (Reasoning) has the edge for knowledge tasks in this comparison, averaging 87.2 versus 59.4. Inside this category, GPQA is the benchmark that creates the most daylight between them.
Which is better for coding, Claude 3.5 Sonnet or Kimi K2.5 (Reasoning)?
Kimi K2.5 (Reasoning) has the edge for coding in this comparison, averaging 76.8 versus 49. Inside this category, SWE-bench Verified 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.