GPT-5.5 Pro
Summary
GPT-5.5 Pro is a proprietary language model from OpenAI, released on 23 Apr 2026. It accepts text, images and PDFs and generates text, with a 1.1M-token context window and up to 128K output tokens per response. As of 4 Oct 2026, the lowest listed API price is $30 per million input tokens and $180 per million output tokens (OpenAI API), across 3 providers we track.
Highest-accuracy GPT-5.5 tier for slower, precision-heavy reasoning and coding
Last verified 4 Oct 2026. Every figure on this page links to its source.
Specifications
| Developer | OpenAI |
|---|---|
| Release date | 23 Apr 2026 [models.dev] |
| Status | Generally available [models.dev] |
| Weights | Proprietary (API only) [models.dev] |
| Context window | 1.1M (1,050,000 tokens) [models.dev] |
| Max output | 128K tokens [models.dev] |
| Knowledge cutoff | 1 Dec 2025 [models.dev] |
| Input | Text, images and PDFs [models.dev] |
| Output | Text [models.dev] |
| Reasoning mode | Yes [models.dev] |
| Tool calling | Yes [models.dev] |
| Structured output | Yes [models.dev] |
GPT-5.5 Pro API pricing by provider
USD per million tokens. Sorted by input price.
| Provider | Input | Output | Cached input | Context | Source |
|---|---|---|---|---|---|
| OpenAI API gpt-5.5-pro | $30 | $180 | – | 1.1M | models.dev, 4 Oct 2026 |
| OpenRouter openai/gpt-5.5-pro | $30 | $180 | – | 1.1M | OpenRouter, 4 Oct 2026 |
| Vercel AI Gateway openai/gpt-5.5-pro | $30 | $180 | – | 1M | models.dev, 4 Oct 2026 |
Frequently asked questions
What is the context window of GPT-5.5 Pro?
GPT-5.5 Pro has a context window of 1,050,000 tokens (1.1M) and can generate up to 128,000 tokens in a single response, according to models.dev.
How much does the GPT-5.5 Pro API cost?
Through OpenAI API, GPT-5.5 Pro costs $30 per million input tokens and $180 per million output tokens. Prices last verified 4 Oct 2026.
Is GPT-5.5 Pro open source?
No. GPT-5.5 Pro is a proprietary model; OpenAI has not released its weights. It is available through APIs including OpenAI API, OpenRouter, Vercel AI Gateway.
When was GPT-5.5 Pro released?
OpenAI released GPT-5.5 Pro on 23 Apr 2026, according to models.dev.
Which providers offer GPT-5.5 Pro?
We track GPT-5.5 Pro on 3 providers: OpenAI API, OpenRouter, Vercel AI Gateway.
Change history
No changes detected since we started tracking this model. We re-check every source daily.