Model comparison
GPT-5.1 vs Kimi K2.5 (Reasoning)
Head-to-head evidence from 19 shared benchmark results across 6 categories. Overall scores shown here use the public BenchAlign v5 ranking lane.
Public leaderboard positions: GPT-5.1 #94 (Estimated); Kimi K2.5 (Reasoning) #57 (Estimated). Intervals and evidence labels describe ranking uncertainty, not a guarantee for a specific workload.
Evidence parity. GPT-5.1 and Kimi K2.5 (Reasoning) share 19 comparable benchmark results. 0 of 8 categories are comparable. 2 results are unique to GPT-5.1; 8 to Kimi K2.5 (Reasoning).
Updated July 20, 2026- Shared results
- 19
- GPT-5.1 only
- 2
- Kimi K2.5 (Reasoning) only
- 8
- Comparable categories
- 0 / 8
Benchmark data for GPT-5.1 and Kimi K2.5 (Reasoning) is coming soon on BenchLM.
Confidence note. This is a partial-evidence comparison with 19 shared benchmark results across 6 evidence categories; 0 of 8 categories currently have scoreable aggregates for both models. Treat the verdict as directional until coverage is more balanced.
Why this result
BenchLM has partial data for these models, but not enough overlapping benchmark coverage to produce a fair score-level comparison yet.
GPT-5.1 is priced at $1.25 input / $10.00 output per 1M tokens, versus $0.60 input / $3.00 output per 1M tokens for Kimi K2.5 (Reasoning). GPT-5.1 has 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 | GPT-5.1 | Δ | Kimi K2.5 (Reasoning) |
|---|---|---|---|
| Agentic | GPT-5.1Not measured | MarginNo overlap | Kimi K2.5 (Reasoning)55.0 |
| Coding | GPT-5.1Not measured | MarginNo overlap | Kimi K2.5 (Reasoning)76.8 |
| Knowledge | GPT-5.1Not measured | MarginNo overlap | Kimi K2.5 (Reasoning)87.2 |
| Math | GPT-5.126.4 | MarginNo overlap | Kimi K2.5 (Reasoning)Not measured |
| Multimodal | GPT-5.1Not measured | MarginNo overlap | Kimi K2.5 (Reasoning)78.5 |
Operational comparison
Runtime and commercial metrics are compared only when both models have a complete sourced value.
| Metric | GPT-5.1 | Kimi K2.5 (Reasoning) | Comparison |
|---|---|---|---|
| Input / output priceUSD per 1M tokens | GPT-5.1$1.25 input / $10 output | Kimi K2.5 (Reasoning)$0.6 input / $3 output | Kimi K2.5 (Reasoning) has the lower combined listed price. |
| Generation speedtokens per second | GPT-5.1111 tok/s | Kimi K2.5 (Reasoning)Not available | A complete speed comparison is not available. |
| First-answer latencyseconds to first token | GPT-5.157.47 s | Kimi K2.5 (Reasoning)Not available | A complete latency comparison is not available. |
| Context windowmaximum listed tokens | GPT-5.1200K | Kimi K2.5 (Reasoning)128K | GPT-5.1 lists the larger context window. |
Benchmark Deep Dive
Agentic8 benchmarks
| Benchmark | GPT-5.1 | Kimi K2.5 (Reasoning) | Result |
|---|---|---|---|
| AA Agentic IndexSource | 21.0% | 21.7% | Kimi K2.5 (Reasoning) leads |
| τ²-bench resultsSource | 81.9% | 95.9% | Kimi K2.5 (Reasoning) leads |
| Gert LabsSource | 41.24% | 32.58% | GPT-5.1 leads |
| GDPval-AASource | 24.4% | 25.4% | Kimi K2.5 (Reasoning) leads |
| GDPval-AASource | 987 | 1009 | Kimi K2.5 (Reasoning) leads |
| Terminal-Bench 2.0Source | — | 50.8% | Not comparable |
| BrowseCompSource | — | 60.6% | Not comparable |
| APEX-Agents-AASource | — | 11.5% | Not comparable |
Coding4 benchmarks
Reasoning2 benchmarks
Knowledge8 benchmarks
| Benchmark | GPT-5.1 | Kimi K2.5 (Reasoning) | Result |
|---|---|---|---|
| Artificial Analysis Intelligence IndexSource | 36.9% | 35.4% | GPT-5.1 leads |
| AA-GPQA DiamondSource | 87.3% | 87.9% | Kimi K2.5 (Reasoning) leads |
| AA-HLESource | 26.5% | 29.4% | Kimi K2.5 (Reasoning) leads |
| AA-Omniscience IndexSource | 5.6% | -8.1% | GPT-5.1 leads |
| AA-Omniscience AccuracySource | 37.6% | 34.3% | GPT-5.1 leads |
| AA-Omniscience Hallucination RateSource | 51.3% | 64.6% | GPT-5.1 leads |
| GPQASource | — | 87.6% | Not comparable |
| MMLU-ProSource | — | 87.1% | Not comparable |
Math3 benchmarks
Multimodal3 benchmarks
Inst. Following1 benchmarks
| Benchmark | GPT-5.1 | Kimi K2.5 (Reasoning) | Result |
|---|---|---|---|
| AA-IFBenchSource | 72.9% | 70.2% | GPT-5.1 leads |
Frequently Asked Questions (3)
Can I compare GPT-5.1 and Kimi K2.5 (Reasoning) on BenchLM yet?
Not fully yet. BenchLM is tracking both models, but the sourced benchmark breakdown for this comparison is still coming soon.
Why does this comparison show “coming soon”?
BenchLM only shows category winners and benchmark-level calls when we have sourced results that can be compared fairly. For these models, the public benchmark coverage is not complete enough yet.
What data is available for GPT-5.1 and Kimi K2.5 (Reasoning) today?
GPT-5.1: $1.25 input / $10.00 output per 1M tokens Kimi K2.5 (Reasoning): $0.60 input / $3.00 output per 1M tokens Both model pages still include creator, context window, reasoning mode, and other metadata while benchmark coverage fills in.
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