Grok 4 vs GPT-5.6 Luna
Side-by-side specs, pricing and capabilities. Both models run on Clade under one subscription, so you can switch between them in the same conversation.
Grok 4 comes from xAI and GPT-5.6 Luna from OpenAI. The practical difference for most people is context, price, and which input types each one accepts.
GPT-5.6 Luna holds more in a single conversation — 1.1M tokens against 256K — which matters for long documents and large codebases.
GPT-5.6 Luna is the cheaper of the two on input tokens at $0.20 / 1M tokens.
| Specification | Grok 4 | GPT-5.6 Luna |
|---|---|---|
| Provider | xAI | OpenAI |
| Model ID | grok-4-0709 | gpt-5.6-luna |
| Context window | 256K | 1.1M |
| Max output | — | 128K |
| Input price | $3.00 / 1M tokens | $0.20 / 1M tokens |
| Output price | $15.00 / 1M tokens | $0.02 / 1M tokens |
| Knowledge cutoff | — | — |
| Input types | text, image, file, audio | text, image, file, audio |
| Output types | text | text |
| Plan | Premium | Free |
Which should you use?
Pick GPT-5.6 Luna when…
- You need the larger context window — 1.1M against 256K.
- Cost matters: input runs at $0.20 / 1M tokens versus $3.00 / 1M tokens.
- You want longer single responses — up to 128K output tokens.
- You are on the free plan — this model is included without an upgrade.
Related comparisons
Try both on Clade
You do not have to choose. One Clade subscription gives you Grok 4, GPT-5.6 Luna, and every other model on the platform.