Model comparison
GPT-5.5 Pro vs Kimi K2.5
Head-to-head evidence from 5 shared benchmark results across 4 categories. Overall scores shown here use the public BenchAlign v5 ranking lane.
Public leaderboard positions: GPT-5.5 Pro #38 (Estimated); Kimi K2.5 #54 (Supported). Intervals and evidence labels describe ranking uncertainty, not a guarantee for a specific workload.
Evidence parity. GPT-5.5 Pro and Kimi K2.5 share 5 comparable benchmark results. 3 of 8 categories are comparable. 2 results are unique to GPT-5.5 Pro; 58 to Kimi K2.5.
Updated July 22, 2026- Shared results
- 5
- GPT-5.5 Pro only
- 2
- Kimi K2.5 only
- 58
- Comparable categories
- 3 / 8
Pick GPT-5.5 Pro if you want the stronger benchmark profile. Kimi K2.5 only becomes the better choice if mathematics is the priority or you want the cheaper token bill.
Confidence note. This is a partial-evidence comparison with 5 shared benchmark results across 4 evidence categories; 3 of 8 categories currently have scoreable aggregates for both models. Treat the verdict as directional until coverage is more balanced.
Why this result
GPT-5.5 Pro is clearly ahead on the BenchAlign aggregate, 63.69 to 59.66. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.
GPT-5.5 Pro's sharpest advantage is in agentic, where it averages 90.1 against 55. The single biggest benchmark swing on the page is FrontierMath v2 (Tier 4), 39.600% to 4.200%. Kimi K2.5 does hit back in mathematics, so the answer changes if that is the part of the workload you care about most.
GPT-5.5 Pro is also the more expensive model on tokens at $30.00 input / $180.00 output per 1M tokens, versus $0.60 input / $3.00 output per 1M tokens for Kimi K2.5. That is roughly 60.0x on output cost alone. GPT-5.5 Pro 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. GPT-5.5 Pro gives you the larger context window at 1M, compared with 256K for Kimi K2.5.
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 | GPT-5.5 Pro | Δ | Kimi K2.5 |
|---|---|---|---|
| Agentic | GPT-5.5 Pro90.1 | Margin← 35.1 | Kimi K2.555.0 |
| Math | GPT-5.5 Pro48.1 | Margin→ 12.5 | Kimi K2.560.6 |
| Knowledge | GPT-5.5 Pro57.2 | Margin← 0.3 | Kimi K2.556.9 |
| Coding | GPT-5.5 ProNot measured | MarginNo overlap | Kimi K2.559.4 |
| Reasoning | GPT-5.5 ProNot measured | MarginNo overlap | Kimi K2.561.0 |
| Multilingual | GPT-5.5 ProNot measured | MarginNo overlap | Kimi K2.582.3 |
| Multimodal | GPT-5.5 ProNot measured | MarginNo overlap | Kimi K2.578.5 |
| Inst. Following | GPT-5.5 ProNot measured | MarginNo overlap | Kimi K2.593.9 |
Decisive benchmark drivers
The largest measured benchmark gaps in this matchup, with exact reported values.
More
- Source ↗
FrontierMath v2 (Tier 4)
MathA 39.600%B 4.200%Winner: GPT-5.5 ProΔ 35.4FrontierMath v2 (Tier 4): GPT-5.5 Pro scored 39.600%; Kimi K2.5 scored 4.200%. GPT-5.5 Pro wins this benchmark. - Source ↗
BrowseComp
AgenticA 90.1%B 60.6%Winner: GPT-5.5 ProΔ 29.5BrowseComp: GPT-5.5 Pro scored 90.1%; Kimi K2.5 scored 60.6%. GPT-5.5 Pro wins this benchmark. - Source ↗
HLE
KnowledgeA 57.2%B 30.1%Winner: GPT-5.5 ProΔ 27.1HLE: GPT-5.5 Pro scored 57.2%; Kimi K2.5 scored 30.1%. GPT-5.5 Pro wins this benchmark. - Source ↗
FrontierMath v2 (Tiers 1-3)
MathA 51.000%B 27.900%Winner: GPT-5.5 ProΔ 23.1FrontierMath v2 (Tiers 1-3): GPT-5.5 Pro scored 51.000%; Kimi K2.5 scored 27.900%. GPT-5.5 Pro wins this benchmark.
Operational comparison
Runtime and commercial metrics are compared only when both models have a complete sourced value.
| Metric | GPT-5.5 Pro | Kimi K2.5 | Comparison |
|---|---|---|---|
| Input / output priceUSD per 1M tokens | GPT-5.5 Pro$30 input / $180 output | Kimi K2.5$0.6 input / $3 output | Kimi K2.5 has the lower combined listed price. |
| Generation speedtokens per second | GPT-5.5 ProNot available | Kimi K2.545 tok/s | A complete speed comparison is not available. |
| First-answer latencyseconds to first token | GPT-5.5 ProNot available | Kimi K2.52.38 s | A complete latency comparison is not available. |
| Context windowmaximum listed tokens | GPT-5.5 Pro1M | Kimi K2.5256K | GPT-5.5 Pro lists the larger context window. |
Benchmark Deep Dive
AgenticGPT-5.5 Pro wins19 benchmarks
| Benchmark | GPT-5.5 Pro | Kimi K2.5 | Result |
|---|---|---|---|
| BrowseCompSource | 90.1% | 60.6% | GPT-5.5 Pro leads |
| Terminal-Bench 2.0Source | — | 50.8% | 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 |
| τ²-bench resultsSource | — | 95.9% | Not comparable |
| APEX-Agents-AASource | — | 11.5% | Not comparable |
| Gert LabsSource | — | 45.88% | Not comparable |
| ResearchClawBenchSource | — | 14.0% | Not comparable |
| JobBenchSource | — | 8.7% | Not comparable |
| AA Agentic IndexSource | — | 21.7% | Not comparable |
| GDPval-AASource | — | 25.4% | Not comparable |
| GDPval-AASource | — | 1009 | Not comparable |
Coding10 benchmarks
| Benchmark | GPT-5.5 Pro | Kimi K2.5 | Result |
|---|---|---|---|
| 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 |
| AA-SciCodeSource | — | 49.0% | Not comparable |
| AA Coding IndexSource | — | 46.8% | Not comparable |
Reasoning3 benchmarks
KnowledgeGPT-5.5 Pro wins13 benchmarks
| Benchmark | GPT-5.5 Pro | Kimi K2.5 | Result |
|---|---|---|---|
| HLESource | 57.2% | 30.1% | GPT-5.5 Pro leads |
| HLE w/o toolsSource | 43.1% | — | Not comparable |
| 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 |
| 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 |
MathKimi K2.5 wins10 benchmarks
| Benchmark | GPT-5.5 Pro | Kimi K2.5 | Result |
|---|---|---|---|
| FrontierMath (legacy)Source | 52.4% | — | Not comparable |
| FrontierMath v2 (Tiers 1-3)Source | 51.000% | 27.900% | GPT-5.5 Pro leads |
| FrontierMath v2 (Tier 4)Source | 39.600% | 4.200% | GPT-5.5 Pro 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 |
Multilingual2 benchmarks
Multimodal6 benchmarks
Frequently Asked Questions (4)
Which is better, GPT-5.5 Pro or Kimi K2.5?
GPT-5.5 Pro is ahead on BenchLM's BenchAlign leaderboard, 63.69 to 59.66. The biggest single separator in this matchup is FrontierMath v2 (Tier 4), where the scores are 39.600% and 4.200%.
Which is better for knowledge tasks, GPT-5.5 Pro or Kimi K2.5?
GPT-5.5 Pro has the edge for knowledge tasks in this comparison, averaging 57.2 versus 56.9. Inside this category, HLE is the benchmark that creates the most daylight between them.
Which is better for math, GPT-5.5 Pro or Kimi K2.5?
Kimi K2.5 has the edge for math in this comparison, averaging 60.6 versus 48.1. Inside this category, FrontierMath v2 (Tier 4) is the benchmark that creates the most daylight between them.
Which is better for agentic tasks, GPT-5.5 Pro or Kimi K2.5?
GPT-5.5 Pro has the edge for agentic tasks in this comparison, averaging 90.1 versus 55. Inside this category, BrowseComp 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.
Related Comparisons
Explore More
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.