Advancing the price-performance frontier with GPT-5.6

Yesterday, we shared how GPT‑5.6 ⁠ helped make itself more efficient to run ⁠ . Today, we’re passing those gains on to customers with lower prices for GPT‑5.6 Luna ⁠ (opens in a new window) and Terra ⁠ (opens in a new window) and faster performance with GPT‑5.6 Sol ⁠ in the API. Together, these updates help customers get more from every dollar they invest in AI and move faster when time matters.

Starting today, GPT‑5.6 Luna, our fastest and most affordable model, will cost 80% less, while GPT‑5.6 Terra, our balanced model for everyday work, will cost 20% less. These lower prices for Luna and Terra are also reflected in how usage is counted against paid subscriptions when using Codex and ChatGPT Work. Luna gives businesses a far more cost-effective way to handle high-volume work at very high levels of quality. It can use tools and complete multi-step workflows, making a broader range of AI applications practical to run at scale.

Making advanced intelligence more abundant and affordable is central to OpenAI’s mission to ensure AGI benefits all of humanity. These changes put that commitment into practice. They reflect years of improvements in how our models are built, served, and put to work.

Using AI efficiently begins with the outcome. The stakes, cost of error, urgency, and scale determine the right balance of intelligence, speed, reliability, and cost. That balance can change from one step of a workflow to the next.

In practice, businesses can define the outcome and quality standard they need, then use evaluations to determine where additional intelligence materially improves the result and where faster, lower-cost processing can deliver the same quality. A coding workflow, for example, might use Sol to resolve uncertainty and define the plan, then use Luna to implement well-specified changes, write and run tests, and evaluate the results. Another workflow may call for a different balance.

Starting July 30, API pricing is $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. Sol pricing remains unchanged. ChatGPT and Codex subscription prices and quota budgets remain unchanged, while Terra and Luna usage now consumes fewer credits. Pricing changes will begin rolling out in AWS later today.

Fast mode for GPT‑5.6 Sol replaces Priority Processing in the API and aligns with /fast in Codex. Existing API requests tagged priority will continue to work. View complete API pricing details. ⁠

We’re also introducing Fast mode in the API, which replaces our Priority Processing offering. For GPT‑5.6 Sol, Fast mode now delivers up to 2.5× faster speeds than Standard processing at twice the price, with no change in intelligence. Fast mode is backward compatible: requests tagged priority will automatically use Fast mode.

GPT‑5.6 gives businesses much more room to optimize that equation. Luna delivers performance comparable to models that were frontier-class a year ago at roughly 6 cents on the dollar per task, and at nearly nine times the speed. On professional work, as measured by Agents’ Last Exam, Luna outperforms Fable 5 at an estimated cost per task nearly 99% lower.

The GPT‑5.6 family expands the range of those choices. Businesses can apply the maximum useful intelligence at every stage while paying the right price for the value it creates.