Explainers · Last checked Oct 19, 2026

GPT-5.6 Sol promo pricing: $4 / $20 per 1M tokens, guaranteed at least through Nov 21, 2026

OpenAI is offering GPT-5.6 Sol at a promotional price of $4 per 1M input tokens and $20 per 1M output tokens ($0.40 per 1M cached input). OpenAI says this pricing is available “at least through November 21, 2026”.

How long the price lasts

That date is a guaranteed minimum, not an announced end date. OpenAI has not announced a last day for the promo or what Sol will cost afterwards. Budget with that in mind: the promo price is guaranteed at least through November 21, 2026, and OpenAI hasn't announced anything about pricing after that.

Compared with GPT-5.5

OpenAI's model page lists GPT-5.5 at $5 input / $30 output per 1M tokens, so the Sol promo is about 20% cheaper on input and 33% cheaper on output at the promo price.

Watch out for long prompts

Per the same page, prompts with more than 272K input tokens are billed at 2× the input rate and 1.5× the output rate for the whole request.

Why this matters now

OpenAI names Sol as the replacement for many of the models it listed for shutdown on Oct 23, 2026 (gpt-4, gpt-4-turbo, o1, o3-mini and others), so a lot of migrated traffic will land on promo pricing. See the Oct 23 shutdown list.