GPT-5.6 Luna
The cheapest way to get a million token context window from a major lab, after an 80 percent price cut in July 2026.
The facts at a glance
Pricing last checked August 7, 2026. Prices change and vary by region. Check the official pricing page ↗
Assessment
What it does well
- The full 1.05 million token context at the lowest price in the family
- Cut by 80 percent on 30 July 2026, which reset the price floor for large context work
- Now the default model for ChatGPT Free and Go users
Where it falls short
- The lowest capability tier of the three GPT-5.6 models
- OpenAI's launch blog and docs pricing page quote conflicting rates, which we have not been able to reconcile
- Not suited to work where a reasoning error is expensive to catch
Privacy and data control
API use is governed by OpenAI platform terms. If you reach Luna through ChatGPT rather than the API, the consumer data controls described on the ChatGPT profile apply instead.
The longer read
Why the price cut mattered
On 30 July 2026 OpenAI cut Luna by 80 percent and Terra by 20 percent. The interesting part is not the discount, it is what it signals: a million token context is no longer a premium feature, and the competitive pressure has moved from capability alone to cost per useful answer.
How it performs by outcome
We assess products against a job, not a leaderboard. These are the outcomes this entry is compared under.
Worth comparing against
How this profile was produced
Source review. Every fact here is drawn from the provider documentation linked below and checked on the date shown. We have not yet run this entry through a controlled test, and no scoring is implied.
Read the full review methodology →