OpenAI lowers GPT-5.6 prices and adds faster API mode

OpenAI said it is lowering prices for GPT5.6 Luna and Terra and improving API speed with a new Fast mode for GPT5.6 Sol. The changes were announced on July 30, 2026 and are aimed at giving enterprise customers better performance per dollar across a range of workloads. According to the company, GPT5.6 Luna will cost 80% less and Terra will cost 20% less starting today. OpenAI said the lower prices also apply when these models are used through paid subscriptions in Codex and ChatGPT Work, while Sol remains priced the same. OpenAI also introduced Fast mode in the API, replacing Priority Processing. For GPT5.6 Sol, Fast mode offers up to 2.5 times faster speeds than Standard processing at twice the price, with no change in intelligence. The company said the update is designed to help customers choose the right mix of speed, quality, and cost for different tasks.