OpenAI cuts GPT-5.6 Luna by 80%… Terra also down 20%

OpenAI cut the input and output prices for Luna, its lowest-cost GPT-5.6 model, by 80%.

The mid-tier Terra model also got a 20% price reduction, lowering costs for budget-sensitive developers.

The top coding model Sol kept its base price, but OpenAI introduced a new faster Fast Mode to replace the old priority-processing plan.

Usage accounting for paid plans was also adjusted, so Luna and Terra now consume fewer credits in ChatGPT Work and Codex.

The changes intensify AI pricing competition and could sharpen rivalry with Chinese open-weight models.