GPT-5.6 Sol's $4 / $20 API Price Is a Promotion Through at Least November 21
OpenAI lowered the API price of GPT-5.6 Sol on August 21, 2026, to $4 per million input tokens and $20 per million output tokens. The changelog describes it as 20% lower on input and 33% lower on output. OpenAI’s pricing page adds the catch: “GPT-5.6 Sol’s promotional pricing is available at least through November 21, 2026.”
What the numbers imply
A 20% cut to $4 and a 33% cut to $20 put the previous price at $5 input and $30 output. OpenAI has not said whether Sol returns to that rate, moves to a new one, or keeps $4 / $20 after November 21. When we checked on September 15, openai.com’s marketing pricing page still showed $5 / $30, while the developer docs showed $4 / $20.
GPT-5.6 Sol prices today
| Tier | Prompt size | Input | Cached input | Cache writes | Output |
|---|---|---|---|---|---|
| Standard | up to 272K | $4.00 | $0.40 | $5.00 | $20.00 |
| Standard | over 272K | $8.00 | $0.80 | $10.00 | $30.00 |
| Batch and Flex | up to 272K | $2.00 | $0.20 | $2.50 | $10.00 |
| Fast mode | up to 272K | $8.00 | $0.80 | $10.00 | $40.00 |
Third-party catalogs add to the confusion. OpenRouter lists $2 / $10, the same as OpenAI’s Batch and Flex rates rather than the standard rate.
The rest of the GPT-5.6 family
OpenAI released GPT-5.6 Sol, Terra and Luna on July 9, 2026; the gpt-5.6 alias routes to Sol. On July 30 it cut Luna’s price by 80% and Terra’s by 20%. OpenAI did not label those cuts as promotions. Terra now costs $2 / $12 and Luna $0.20 / $1.20. The same day, Fast mode replaced Priority processing; it runs up to 2.5 times faster than standard for GPT-5.6 Sol at twice the price.
Planning for November
If Sol’s price reverts to $5 / $30, a request with 1,000 input and 500 output tokens goes from $0.014 to $0.020, about 43% more. Workloads that write long outputs feel it most. Budgets that run past November 21 should either assume the higher rate or keep Terra as a fallback.
We track Sol’s price across sources on the GPT-5.6 Sol model card. All OpenAI rates are on the OpenAI API pricing page.