Model comparison
GPT-5.5 Pro vs Kimi K2
Head-to-head evidence from 3 shared benchmark results across 2 categories. Overall scores shown here use the public BenchAlign v5 ranking lane.
Public leaderboard positions: GPT-5.5 Pro #38 (Estimated); Kimi K2 #189 (Supported). Intervals and evidence labels describe ranking uncertainty, not a guarantee for a specific workload.
Evidence parity. GPT-5.5 Pro and Kimi K2 share 3 comparable benchmark results. 1 of 8 categories are comparable. 4 results are unique to GPT-5.5 Pro; 11 to Kimi K2.
Updated July 22, 2026- Shared results
- 3
- GPT-5.5 Pro only
- 4
- Kimi K2 only
- 11
- Comparable categories
- 1 / 8
Pick GPT-5.5 Pro if you want the stronger benchmark profile. Kimi K2 only becomes the better choice if you want the cheaper token bill or you would rather avoid the extra latency and token burn of a reasoning model.
Confidence note. This is a partial-evidence comparison with 3 shared benchmark results across 2 evidence categories; 1 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 27.19. 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 mathematics, where it averages 48.1 against 16.1. The single biggest benchmark swing on the page is FrontierMath v2 (Tier 4), 39.600% to 0.000%.
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 / $2.50 output per 1M tokens for Kimi K2. That is roughly 72.0x on output cost alone. GPT-5.5 Pro is the reasoning model in the pair, while Kimi K2 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 128K for Kimi K2.
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 |
|---|---|---|---|
| Math | GPT-5.5 Pro48.1 | Margin← 32.0 | Kimi K216.1 |
| Agentic | GPT-5.5 Pro90.1 | MarginNo overlap | Kimi K2Not measured |
| Knowledge | GPT-5.5 Pro57.2 | MarginNo overlap | Kimi K2Not measured |
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 0.000%Winner: GPT-5.5 ProΔ 39.6FrontierMath v2 (Tier 4): GPT-5.5 Pro scored 39.600%; Kimi K2 scored 0.000%. GPT-5.5 Pro wins this benchmark. - Source ↗
FrontierMath v2 (Tiers 1-3)
MathA 51.000%B 21.404%Winner: GPT-5.5 ProΔ 29.6FrontierMath v2 (Tiers 1-3): GPT-5.5 Pro scored 51.000%; Kimi K2 scored 21.404%. 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 | Comparison |
|---|---|---|---|
| Input / output priceUSD per 1M tokens | GPT-5.5 Pro$30 input / $180 output | Kimi K2$0.6 input / $2.5 output | Kimi K2 has the lower combined listed price. |
| Generation speedtokens per second | GPT-5.5 ProNot available | Kimi K243 tok/s | A complete speed comparison is not available. |
| First-answer latencyseconds to first token | GPT-5.5 ProNot available | Kimi K21.51 s | A complete latency comparison is not available. |
| Context windowmaximum listed tokens | GPT-5.5 Pro1M | Kimi K2128K | GPT-5.5 Pro lists the larger context window. |
Benchmark Deep Dive
Agentic2 benchmarks
Coding1 benchmarks
| Benchmark | GPT-5.5 Pro | Kimi K2 | Result |
|---|---|---|---|
| AA-SciCodeSource | — | 34.5% | Not comparable |
Reasoning2 benchmarks
Knowledge8 benchmarks
| Benchmark | GPT-5.5 Pro | Kimi K2 | Result |
|---|---|---|---|
| HLESource | 57.2% | — | Not comparable |
| HLE w/o toolsSource | 43.1% | — | Not comparable |
| Artificial Analysis Intelligence IndexSource | — | 19.4% | Not comparable |
| AA-GPQA DiamondSource | — | 76.6% | Not comparable |
| AA-HLESource | — | 7.0% | Not comparable |
| AA-Omniscience IndexSource | — | -27.5% | Not comparable |
| AA-Omniscience AccuracySource | — | 26.8% | Not comparable |
| AA-Omniscience Hallucination RateSource | — | 74.2% | Not comparable |
MathGPT-5.5 Pro wins3 benchmarks
Multimodal1 benchmarks
| Benchmark | GPT-5.5 Pro | Kimi K2 | Result |
|---|---|---|---|
| Design Arena WebsiteSource | — | 1080 | Not comparable |
Inst. Following1 benchmarks
| Benchmark | GPT-5.5 Pro | Kimi K2 | Result |
|---|---|---|---|
| AA-IFBenchSource | — | 41.5% | Not comparable |
Frequently Asked Questions (2)
Which is better, GPT-5.5 Pro or Kimi K2?
GPT-5.5 Pro is ahead on BenchLM's BenchAlign leaderboard, 63.69 to 27.19. The biggest single separator in this matchup is FrontierMath v2 (Tier 4), where the scores are 39.600% and 0.000%.
Which is better for math, GPT-5.5 Pro or Kimi K2?
GPT-5.5 Pro has the edge for math in this comparison, averaging 48.1 versus 16.1. Inside this category, FrontierMath v2 (Tier 4) is the benchmark that creates the most daylight between them.
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