OpenAI
PreviewGPT-5.6 Luna pricing
The low-cost tier of OpenAI's June 2026 GPT-5.6 family, tuned for fast everyday work: summarisation, drafting, and routine automation.
Input
$1.00/ 1M tok
Output
$6.00/ 1M tok
- Context window
- 1.5M
- Max output
- 128K
- Cached input
- $0.1000 / 1M
- Verified
- 2026-07-01
GPT-5.6 family
| Tier | Input / 1M | Output / 1M | Cached in / 1M |
|---|---|---|---|
Sol Hardest problems: complex coding, security research | $5.00 | $30.00 | $0.5000 |
Terra High-volume business tasks | $2.50 | $15.00 | $0.2500 |
Luna (this page) Fast everyday work | $1.00 | $6.00 | $0.1000 |
Luna is the new low-cost tier, creating a cheaper production price point than GPT-5.5 offered. GPT-5.6 launched in limited preview on 26 June 2026 (~20 organisations).
GPT-5.6 Luna is the low-cost tier of OpenAI's three-model GPT-5.6 family, released 26 June 2026. It is built for fast, everyday work – summarisation, drafting, and routine automation – at $1 per 1M input tokens and $6 per 1M output tokens. Luna creates a cheaper high-volume production price point than GPT-5.5 offered, a fifth of the Sol rate.
Luna shares the family's ~1.5M-token context window and improved prompt caching: cache reads bill at $0.10 / 1M (the 90% discount), and cache writes at 1.25x uncached input with explicit breakpoints and a 30-minute minimum cache life. For large-scale, latency-tolerant pipelines, that cached rate can dominate the effective cost.
Use Luna as the default for high-volume, lower-difficulty traffic and escalate to Terra or Sol only where a task needs the extra capability. As of launch the models are limited to a small preview cohort.
Estimate LLM costs before you send
Paste your prompt into the Calcis estimator to see token counts and per-request cost across every tracked model, then compare GPT-5.6 Luna against them side by side.
Frequently asked
- How much does GPT-5.6 Luna cost per 1M tokens?
- $1 for input and $6 for output per 1M tokens. Cached input reads bill at $0.10 / 1M (a 90% discount).
- When should I use Luna instead of Terra or Sol?
- Luna is tuned for fast everyday work like summarisation, drafting, and routine automation. Step up to Terra ($2.50/$15) for high-volume business tasks or Sol ($5/$30) for the hardest coding and security work.
- What is the GPT-5.6 Luna context window?
- Reported at approximately 1.5M tokens, the same as the rest of the GPT-5.6 family. OpenAI has not published an official figure at launch.
- Is Luna the cheapest GPT-5.6 tier?
- Yes. At $1/$6 per 1M tokens it is a fifth of the Sol price and creates a lower production price point than GPT-5.5 offered.
- Is GPT-5.6 Luna generally available?
- Not at launch. It debuted 26 June 2026 for a limited preview cohort of roughly 20 organisations, with wider availability expected in the following weeks.
Pricing verified 2026-07-01 from the provider's rate card. These figures are informational and not yet wired into the Calcis estimator or billing.