GPT-5.5 vs Kimi K2 Thinking
Head-to-head specifications
| Metric | GPT-5.5 | Kimi K2 Thinking | Difference |
|---|---|---|---|
| Intelligence Index | 55.0 | 33.0 | +66.7% |
| Context window | 1M tokens | 300K tokens | — |
| Blended price ($/1M tokens) | $1.54 | $0.62 | +148.4% |
| Output speed (tokens/s) | 67 | 131 | -48.9% |
| Access | Proprietary API | Open weights | — |
- GPT-5.5 leads overall capability (Intelligence Index 55.0 vs 33.0).
- Kimi K2 Thinking is the cheaper model to run at $0.62/1M blended tokens — about 2.5× cheaper.
- GPT-5.5 offers the larger context window (1M tokens), useful for long documents and codebases.
Verdict: GPT-5.5 or Kimi K2 Thinking?
GPT-5.5 advantages
- General intelligence (+40%)
- Context window (+70%)
Kimi K2 Thinking advantages
- Affordability (+60%)
- Output speed (+49%)
Which should you choose?
- Choose the GPT-5.5 if you need the strongest overall reasoning and accuracy.
- Choose the Kimi K2 Thinking if you want the lowest cost per token at scale.
- Choose the GPT-5.5 if you work with long documents or large codebases.
Value for money
Kimi K2 Thinking offers more intelligence per dollar (1.5× the Intelligence-Index-per-cost of the alternative), making it the stronger value for high-volume use. It is also open-weight, so self-hosting can reduce costs further at scale.
GPT-5.5 vs Kimi K2 Thinking: which should you choose?
GPT-5.5 — OpenAI multimodal model with an Intelligence Index of 55, a 1M-token context window and a blended price of $1.54/1M tokens.
Kimi K2 Thinking — Moonshot AI text model with an Intelligence Index of 33, a 300K-token context window and a blended price of $0.62/1M tokens (open weights).
GPT-5.5 vs Kimi K2 Thinking: GPT-5.5 scores higher on the Intelligence Index. GPT-5.5 leads overall capability (Intelligence Index 55.0 vs 33.0). Kimi K2 Thinking is the cheaper model to run at $0.62/1M blended tokens — about 2.5× cheaper.
Capability: intelligence, coding and agentic work
On the composite Intelligence Index the GPT-5.5 scores 55.0 versus 33.0. Composite indices summarize many evaluations, but always test on your own workload before committing.
Context window and speed
The GPT-5.5 accepts up to 1 million tokens per request, which sets how much documentation, transcript or code it can reason over at once. In measured throughput, Kimi K2 Thinking generates faster (131 vs 67 tokens/s), which matters for interactive apps and high-volume pipelines.
Pricing and access
At blended per-token rates, Kimi K2 Thinking is the cheaper model to run ($0.62 vs $1.54 per 1M tokens). GPT-5.5 is proprietary api and Kimi K2 Thinking is open weights. Open-weight models can be self-hosted, trading per-call cost for infrastructure you manage; for production also weigh rate limits, throughput and data-residency requirements.
The verdict
Both are credible choices in the ai model comparison space; the specification table above lays out every metric so you can weigh the trade-offs that matter to you. Pick the one whose strengths line up with how you will actually use it.
Frequently asked questions
Is the GPT-5.5 better than the Kimi K2 Thinking?
These two are closely matched — the right pick comes down to which specific strengths you value and the price you actually pay. GPT-5.5 leads overall capability (Intelligence Index 55.0 vs 33.0).
What is the main difference between the GPT-5.5 and the Kimi K2 Thinking?
GPT-5.5 leads overall capability (Intelligence Index 55.0 vs 33.0). Kimi K2 Thinking is the cheaper model to run at $0.62/1M blended tokens — about 2.5× cheaper.
Which is better value?
Kimi K2 Thinking offers more intelligence per dollar (1.5× the Intelligence-Index-per-cost of the alternative), making it the stronger value for high-volume use. It is also open-weight, so self-hosting can reduce costs further at scale.
Which should I choose?
Choose the GPT-5.5 if you need the strongest overall reasoning and accuracy. Choose the Kimi K2 Thinking if you want the lowest cost per token at scale.
Methodology
Large language models are compared on independent leaderboard metrics: an Intelligence Index (a composite of reasoning and knowledge evaluations), Coding and Agentic indices where measured, community arena Elo, maximum context window, a blended API price per million tokens (weighted across cache-hit, input and output rates), and measured output speed in tokens per second. Where a model ships multiple reasoning-effort variants, we report its strongest variant. Benchmarks capture only part of real-world quality, which also depends on tool use, latency, safety and task fit — and this space moves quickly, so figures reflect the leaderboard snapshot on the page date.