GPT Realtime 2 vs Kimi K3
GPT Realtime 2 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 8× the 128k of GPT Realtime 2. Kimi K3 leads on coding, reasoning, general knowledge.
Specs side by side
| Metric | OpenAI GPT Realtime 2 | Z.ai Kimi K3 |
|---|---|---|
| Input price (per 1M) | $4 | $3 |
| Output price (per 1M) | $24 | $15 |
| Context window | 128k tokens | 1.0M tokens |
| Speed tier | ultra | balanced |
| Open weights | No | No |
| EU region | Yes | No |
| Free tier | No | No |
| Prompt caching | No | Yes |
| Vision input | No | Yes |
| Extended thinking | No | Yes |
When to choose each
Choose GPT Realtime 2 if…
- Low latency matters (ultra vs balanced)
- EU data residency is required
- You need realtime speech-to-speech
Choose Kimi K3 if…
- You need 1.0M context (8× more than GPT Realtime 2)
- You need image input / vision
- Coding is central to your workload
- Reasoning is central to your workload
Benchmark delta
GPT Realtime 2 leads on
GPT Realtime 2 has no meaningful benchmark lead in this pair.
Kimi K3 leads on
- Coding
- Reasoning
- General knowledge
- Long-context retrieval
- Instruction following
- Multilingual
- Tool use
FAQ — GPT Realtime 2 vs Kimi K3
GPT Realtime 2 vs Kimi K3 — which is better?
GPT Realtime 2 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 8× the 128k of GPT Realtime 2. Kimi K3 leads on coding, reasoning, general knowledge. The right pick depends on your use case — see "When to choose each" above for a data-driven decision.
How does GPT Realtime 2 pricing compare to Kimi K3?
GPT Realtime 2 costs $4 / $24 per 1M vs Kimi K3 at $3 / $15 per 1M. Kimi K3 is cheaper on output tokens by roughly 60%. Both support prompt caching, which reduces effective cost by 80-90% on repeat system prompts.
Does GPT Realtime 2 or Kimi K3 have the bigger context window?
Kimi K3 has a 1.0M-token context window — 8× the 128k context of GPT Realtime 2. Enough for entire codebases, books, or multi-document RAG.
Is there a free tier for GPT Realtime 2 or Kimi K3?
GPT Realtime 2: no — Paid-only. Kimi K3: no — No free API tier; kimi.com web chat is free with limits.
Which is better for coding — GPT Realtime 2 or Kimi K3?
Kimi K3 leads on coding benchmarks (GPT Realtime 2: 78/100, Kimi K3: 95/100). For production coding agents also weigh tool-use performance — GPT Realtime 2 scores 84, Kimi K3 scores 90.