GPT-5.5 Pro vs Kimi K3
GPT-5.5 Pro and Kimi K3 are both current production-tier models. Kimi K3 is meaningfully cheaper at $3 / $15 per 1M. Kimi K3 has a 1.0M context window — about 3× the 400k of GPT-5.5 Pro. GPT-5.5 Pro leads on reasoning, vision, tool use.
Specs side by side
| Metric | OpenAI GPT-5.5 Pro | Z.ai Kimi K3 |
|---|---|---|
| Input price (per 1M) | $30 | $3 |
| Output price (per 1M) | $180 | $15 |
| Context window | 400k tokens | 1.0M tokens |
| Speed tier | slow | balanced |
| Open weights | No | No |
| EU region | No | No |
| Free tier | No | No |
| Prompt caching | Yes | Yes |
| Vision input | Yes | Yes |
| Extended thinking | Yes | Yes |
When to choose each
Choose GPT-5.5 Pro if…
- HIPAA eligibility is required
- Reasoning is central to your workload
- Vision is central to your workload
Choose Kimi K3 if…
- Cost is a priority ($3 / $15 per 1M vs $30 / $180 per 1M)
- You need 1.0M context (3× more than GPT-5.5 Pro)
Benchmark delta
GPT-5.5 Pro leads on
- Reasoning
- Vision
- Tool use
Kimi K3 leads on
Kimi K3 has no meaningful benchmark lead in this pair.
FAQ — GPT-5.5 Pro vs Kimi K3
GPT-5.5 Pro vs Kimi K3 — which is better?
GPT-5.5 Pro and Kimi K3 are both current production-tier models. Kimi K3 is meaningfully cheaper at $3 / $15 per 1M. Kimi K3 has a 1.0M context window — about 3× the 400k of GPT-5.5 Pro. GPT-5.5 Pro leads on reasoning, vision, tool use. The right pick depends on your use case — see "When to choose each" above for a data-driven decision.
How does GPT-5.5 Pro pricing compare to Kimi K3?
GPT-5.5 Pro costs $30 / $180 per 1M vs Kimi K3 at $3 / $15 per 1M. Kimi K3 is cheaper on output tokens by roughly 1100%. Both support prompt caching, which reduces effective cost by 80-90% on repeat system prompts.
Does GPT-5.5 Pro or Kimi K3 have the bigger context window?
Kimi K3 has a 1.0M-token context window — 3× the 400k context of GPT-5.5 Pro. Enough for entire codebases, books, or multi-document RAG.
Is there a free tier for GPT-5.5 Pro or Kimi K3?
GPT-5.5 Pro: no — Paid-only — no free tier. Kimi K3: no — No free API tier; kimi.com web chat is free with limits.
Which is better for coding — GPT-5.5 Pro or Kimi K3?
GPT-5.5 Pro leads on coding benchmarks (GPT-5.5 Pro: 96/100, Kimi K3: 95/100). For production coding agents also weigh tool-use performance — GPT-5.5 Pro scores 94, Kimi K3 scores 90.