OpenAI Cuts GPT-5.6 Luna Pricing by 80%, Terra by 20%

OpenAI is cutting the price of two GPT-5.6 models, lowering API costs by as much as 80%. The changes also allow ChatGPT Work and Codex subscribers to complete more tasks before exhausting their quota budgets.



Starting July 30, GPT-5.6 Luna, the company's fastest and most affordable model, will cost 80% less than its initial price set earlier this month, while GPT-5.6 Terra, its balanced model for everyday work, will cost 20% less. The new API rates are $2 per million input tokens and $12 per million output tokens for Terra, and $0.20 per million input tokens and $1.20 per million output tokens for Luna. Pricing for GPT-5.6 Sol remains unchanged.


The lower prices are also reflected in how usage is counted against paid subscriptions. Because Terra and Luna now consume fewer credits, ChatGPT Work and Codex subscribers can complete more tasks before exhausting their quota budgets.

The company says the lower prices stem from efficiency gains across every layer of its infrastructure. Within a human-led process, the flagship GPT-5.6 Sol model autonomously rewrote production kernels, designed and ran hundreds of token-generation experiments, and monitored training, intervening when problems arose. The kernel work reduced the end-to-end cost of serving the models by 20%, while the experiments improved token-generation efficiency by more than 15%.

OpenAI is also replacing Priority Processing in the API with a new Fast mode. For GPT-5.6 Sol, it delivers responses up to 2.5× faster than Standard processing at twice the price, with no change in model intelligence. Existing API requests tagged priority will automatically use Fast mode.

OpenAI says Luna delivers performance comparable to frontier-class models from a year ago at roughly 6 cents on the dollar per task, while outperforming Anthropic's Fable 5 on professional work, as measured by Agents' Last Exam, at an estimated cost per task nearly 99% lower.


Pricing changes will begin rolling out on AWS later today.

GPT-5.6 Terra and Luna remain available through ChatGPT Work, Codex, and the OpenAI API. In ChatGPT Work and Codex, Free and Go users can access Terra, while Plus, Pro, Business, and Enterprise subscribers can choose both Terra and Luna.