GPT-5.6 Luna vs Grok 4.3
GPT-5.6 Luna (OpenAI) vs Grok 4.3 (xAI), compared on price, context, speed and Arabic support. Both run on thalam through one OpenAI-compatible API, so you can switch between them with a single model id change. At a glance, GPT-5.6 Luna is the cheaper option.
Specs side by side
| Spec | GPT-5.6 Luna | Grok 4.3 |
|---|---|---|
| Provider | OpenAI | xAI |
| Type | Text | Text |
| Context window | 1M | 1M |
| Max output | 128K | 400K |
| Input price | $0.20 / 1M | $1.25 / 1M |
| Output price | $1.20 / 1M | $2.50 / 1M |
| Speed | Fast | Fast |
| Arabic support | Strong | Partial |
Which should you choose?
- Lower cost, about 6.3× cheaper ($0.20 / 1M)
- Stronger Arabic support for Gulf and MENA use
- xAI's flagship Grok 4.3. Fast, low-hallucination reasoning with strong agentic tool-calling, 1M context, and real-time knowledge
One OpenAI-compatible endpoint, one bill. Switch between them with a single model id change, pay per use, credits never expire.
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FAQ
What's the difference between GPT-5.6 Luna and Grok 4.3?
GPT-5.6 Luna costs less ($0.20 / 1M vs $1.25 / 1M); GPT-5.6 Luna has stronger Arabic support. Both are available on thalam behind one OpenAI-compatible API.
Is GPT-5.6 Luna or Grok 4.3 cheaper?
GPT-5.6 Luna is cheaper on input ($0.20 / 1M vs $1.25 / 1M). On thalam you pay per use, so you can route cheap-by-default and fall back to the other only when needed.
Can I use both GPT-5.6 Luna and Grok 4.3 with one API key?
Yes. thalam is OpenAI-compatible, so both models are reachable through the same endpoint. Switching between them is a one-line model id change, no code rewrite.