GPT-5.6 Luna
OpenAI's fastest and cheapest GPT-5.6 tier for high-volume work.
GPT-5.6 Luna specifications
| Provider | OpenAI |
|---|---|
| Context window | 1,050,000 tokens (1.1M) |
| Input price | $0.20 / 1M tokens |
| Output price | $1.20 / 1M tokens |
| Inputs | Text, Images |
| Reasoning mode | Yes |
| Vision (image input) | Yes |
| Tool / function calling | Yes |
| Native real-time web | Yes |
| Open-weight | No |
| Released | July 2026 |
| Knowledge cutoff | February 2026 |
Pricing & context web-verified August 2026 — confirm on OpenAI's pricing page. Cheapest tier. Prompts over 272K input tokens bill at 2x input and 1.5x output for the whole request.
What GPT-5.6 Luna is best for
- High-volume classification, extraction, and routing
- Cost-sensitive pipelines that still need a large window
- Cheap, fast chat
How to prompt GPT-5.6 Luna
- Give tight, explicit output formats — smaller tiers follow structure better than freeform asks.
- It carries the full 1.05M window, so it is a genuine option for cheap long-context work, not just short prompts.
- Batch similar requests and lean on prompt caching to keep unit costs down.
Work with GPT-5.6 Luna
- Build an optimized prompt with the OpenAI prompt generator.
- Estimate cost with the token counter & cost calculator, or compare every model on the AI model comparison page.
- Related reading: Best Chatgpt Prompts 2026 · Reduce Ai Prompt Costs.
- Official: chatgpt.com
Frequently asked questions
What is GPT-5.6 Luna's context window?
GPT-5.6 Luna has a 1,050,000-token context window (about 1.1M tokens) — the maximum amount of text it can consider at once.
How much does GPT-5.6 Luna cost?
Via the OpenAI API, GPT-5.6 Luna costs $0.20 per 1M input tokens and $1.20 per 1M output tokens (web-verified August 2026). Output tokens cost more, so the length of the model's reply usually drives the bill.
Is GPT-5.6 Luna multimodal?
Yes — GPT-5.6 Luna accepts Text, Images as input, not just text.
Is GPT-5.6 Luna open-weight?
No — GPT-5.6 Luna is available only through the OpenAI API, not as downloadable weights.