GPT-5.5 and GPT-5.5 Pro arrive in the API

OpenAI updated its GPT-5.5 announcement on 24 April to say that GPT-5.5 and GPT-5.5 Pro were available in the API. The standard list price was published as $5 per million input tokens and $30 per million output tokens for GPT-5.5; Pro was listed at $30 and $180 respectively.

The release includes a one-million-token context window in the API. A large window can simplify retrieval-heavy or long-document workflows, but it does not remove the need to select relevant source material and constrain tool access.

For a production estimate, separate input, cached input, output, retries and evaluation traffic. Long context is a capacity limit, not a promise that every token will improve an answer.