GPT-5.6 Luna
A fast, affordable GPT model for everyday tasks
free access available
- Context
- 400,000 tokens
- Type
- Multimodal
- Input
- Text, images
- Developer
- OpenAI
- Strengths
- Speed, price
- Access
- Free + PRO
GPT-5.6 Luna is the junior model in the GPT line: noticeably faster and cheaper than the flagship while keeping OpenAI's signature quality. Ideal for everyday questions, messaging, drafts and quick answers. Available free on ChatPlus.
Luna is built around a simple idea: most questions don't need the heaviest model. Rephrase a paragraph, reply to an email, quickly calculate or explain something — it handles all of that in seconds and is nearly on par with the senior version in quality.
It's Luna that runs in the free tier of ChatPlus, so you can get to know the service with no card at all. And when you hit the ceiling of a task, you switch to Terra right in the same conversation without losing the chat history.
What it's good at
Speed
Instant answers for everyday tasks with no waiting.
Efficiency
Cheap to run — a good fit for high query volumes.
OpenAI quality
The same stack as the flagship, just lighter and faster.
Multimodality
Understands text and images in a single request.
GPT-5.6 Luna and every other model — one plan, one window.
Where it's strongest
GPT next to the others
How GPT-5.6 Luna and the flagships of other labs look side by side. They're all in one ChatPlus subscription.
| Claude | DeepSeek | GPT | Gemini | Grok | GLM | Kimi | Qwen | Muse | GLM 5.3 Flash | |
|---|---|---|---|---|---|---|---|---|---|---|
| Developer | Anthropic | DeepSeek | OpenAI | xAI | Z.ai | Moonshot | Alibaba | Meta | Z.ai | |
| Model | Sonnet 4.6 | DeepSeek V4.1 Reasoner | GPT-5.6 Luna | Gemini 3 Pro | Grok 4 | GLM 5 | Kimi K3 | Qwen 3.8 Max | Muse Spark 1.3 | GLM 5.3 Flash |
| Context | 200K | 128K | 400K | 1M | 256K | 1M | 256K | 256K | 1M | 1M |
| Understands images | — | — | ||||||||
| Live web data | — | — | — | — | — | — | — | |||
| Open source | — | — | — | — | — | |||||
| Key strength | Text and code | Reasoning | Speed | Multimodality | Timeliness | Code and agents | Long context | Complex tasks | Agents and code | Code and agents |
| On ChatPlus |