GPT-5.6 Sol becomes cheaper for API users—for a limited time

OpenAI has cut GPT-5.6 Sol's API price to $4 per million input tokens, $0.40 for cached input and $20 for output. The company says the promotional price will remain available at least through November 21, 2026.

Sol is the flagship member of the GPT-5.6 family. Terra sits below it as the balanced option, while Luna targets fast, high-volume work at a much lower token price.

The change matters most to developers running large workloads. ChatGPT subscriptions use a different pricing system, so a lower API rate does not automatically mean a cheaper monthly ChatGPT plan.

What this means

• Sol now costs $4 input and $20 output per million tokens.
• The lower rate is promotional through at least November 21.
• API pricing and ChatGPT subscriptions are separate.