OpenAI cuts GPT-5.6 Terra prices 20% and Luna 80%

OpenAI cut GPT-5.6 Luna prices by 80% and GPT-5.6 Terra by 20% on July 30, roughly three weeks after the lineup reached users, while keeping Sol's standard pricing unchanged and replacing Priority Processing with a new Fast Mode. Luna now costs $0.20 per million input tokens and $1.20 per million output tokens, Terra costs $2 and $12, and Sol remains at $5 and $30, with Fast Mode priced at $10 and $60 per million tokens and advertised as running Sol up to 2.5 times faster than standard processing. OpenAI said existing Priority Processing users will be migrated automatically and that Terra and Luna will consume fewer credits in ChatGPT Work and Codex without changes to subscription prices or quota budgets. The company attributed some savings to work done by Sol under human supervision, saying the model rewrote production kernels, ran token-generation experiments and monitored training runs, lifting token-generation efficiency by more than 15% and cutting serving costs by 20%. The pricing move comes as lower-cost Chinese open-weight models from DeepSeek, Zhipu and Moonshot continue to attract developers handling large AI workloads, and after concerns over operating costs and model behavior sharpened scrutiny of enterprise AI deployments.