The fastest, cheapest member of the GPT-5.6 family — strong capability at OpenAI's lowest GPT-5.6 price, built for high-volume and latency-sensitive work.
Luna is the entry point to the GPT-5.6 family at $1 / 1M input and $6 / 1M output — a fifth of Sol's output cost for latency-sensitive, high-throughput work.
Luna is the fast-and-affordable tier of the GPT-5.6 family, released publicly on July 9, 2026 alongside Sol and Terra. It's a new price point for OpenAI — $1 input and $6 output per 1M — bringing GPT-5.6-generation capability to workloads that were previously served by mini-class models but need more headroom.
Luna is the model to reach for when throughput and cost dominate: classification, routing, extraction, and high-volume chat where each request is relatively simple but there are a lot of them. It doesn't carry Sol's max/ultra reasoning modes, and it trails Terra on the hardest tasks, but it's dramatically cheaper.
Luna handles everyday generation, summarization, extraction, and lightweight tool use with low latency. It's a natural fit for pipelines that fan out many small calls, and for interactive apps where responsiveness matters more than frontier reasoning. For harder problems, step up to Terra or Sol.
| Model | Input / 1M | Output / 1M | Context |
|---|---|---|---|
| GPT-5.6 Luna | $1 | $6 | 1M |
| GPT-5.6 Terra | $2.50 | $15 | 1M |
| GPT-5.4 mini | $0.25 | $2 | 272K |
| Claude Haiku 4.5 | $1 | $5 | 200K |
| Gemini 3.5 Flash | $1.50 | $9 | 1M |
Luna's closest rival is Claude Haiku 4.5 (equal input, slightly lower output) and Gemini 3.5 Flash. Below it, GPT-5.4 mini and nano remain cheaper still for the simplest tasks.