OpenAI ships GPT-6 Sol and Luna with permanent 50% API price cut

GPT-6 Sol and GPT-6 Luna are the cheaper, faster members of OpenAI's GPT-6 family, released on 22 September 2026, and the part of this launch a reader can check is the price. In his post, Tibo, writing as part of the OpenAI team, says the company is permanently cutting the API price of both models by 50%. He also calls them a very significant improvement across the board, including in writing, but gives no measurements, and OpenAI's own release page could not be retrieved for this explanation, so that quality claim remains his.

The 50% is measured against GPT-5.6. OpenAI's launch post puts it as 50% below GPT-5.6 promotional pricing. Simon Willison's price table shows GPT-6 Sol at $2 per million input tokens and $10 per million output tokens, against $4 and $20 for GPT-5.6 Sol, and GPT-6 Luna at $0.10 and $0.50, against $0.20 and $1.20 for GPT-5.6 Luna. Willison adds that GPT-5.6 has a 25% price increase scheduled for November, which appears to be the contrast behind the word permanently: the old prices were a promotion, while the new ones are presented as the standing rate.

A lower price matters only if the work holds up. Artificial Analysis measured the models the same day and found their Intelligence Index scores level with GPT-5.6, with gains on some evaluations and regressions on others, and GPT-6 Sol costing $1.06 per index task against $1.99 for GPT-5.6 Sol. Cognition reported a similar pattern on its FrontierCode 1.1 coding benchmark, where GPT-6 Sol matched GPT-5.6 Sol at 61% lower cost per task. Tibo also says Plus, Pro and Business subscribers will receive a banked reset and that the cut makes subscription usage go further, without explaining either mechanism. OpenAI used the same kind of credit during the GPT-6 Astra rollout, when it gave paid users one banked reset for each day they lacked Astra access.