OpenAI: GPT-5.5 Pro
GPT-5.5 Pro is a reasoning model from OpenAI released on Apr 8, 2026. It reads text, images and files and writes text, with a 1.05M token context window and up to 128K tokens per reply.
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It costs $30 per million input tokens and $180 per million output tokens.
It supports tool calling and structured JSON output.
19 providers serve it, including Vercel AI Gateway, Poe and AIHubMix. The lowest input price is $27.27 per million tokens at Poe.
- Modalities
- In / out price
- $30 / $180 per 1M
- Context
- 1.05M
- Max output
- 128K
- Released
- Apr 8, 2026
- Knowledge cutoff
- Dec 2025
- Tool calling
- Structured output
- Reasoning
- Prompt caching
- Open weights
- Free to use
GPT-5.5 Pro pricing
USD, as listed on Oct 15, 2026. Most bills are input heavy, so the cached input rate matters as much as the headline price.
| Input | $30 / 1M tokens | |
|---|---|---|
| Output | $180 / 1M tokens | |
| Prompts over 200K | $60 in, $270 out | long context rate |
| Prompts over 272K | $60 in, $270 out | long context rate |
GPT-5.5 Pro providers
19 providers serve it, including Vercel AI Gateway, Poe and AIHubMix. The lowest input price is $27.27 per million tokens at Poe. Each host sets its own price and limits, so the cheapest one is not always the one with the longest context.
| Provider | Input /M | Output /M | Cache read /M | Context | Max output |
|---|---|---|---|---|---|
| OpenAI First party | $30 | $180 | – | 1.05M | 128K |
| Vercel AI Gateway | $30 | $180 | – | 1M | 128K |
| Poe | $27.27 | $163.64 | – | 400K | 128K |
| AIHubMix | $30 | $180 | – | 1.05M | 128K |
| Cloudflare AI Gateway | $30 | $180 | – | 1M | 128K |
| CrossModel | $30 | $180 | – | 1.05M | 128K |
| DevPass (LLM Gateway) | $30 | $180 | – | 1.05M | 128K |
| Eden AI | $30 | $180 | – | 1.05M | 128K |
| FastRouter | $30 | $180 | – | 1.05M | 128K |
| Impossibl | $30 | $180 | $3 | 1.05M | 128K |
| Kilo Gateway | $30 | $180 | – | 1.05M | 128K |
| LLM Gateway | $30 | $180 | – | 1.05M | 128K |
Showing 12 of 19 providers: the lab first, then the major clouds, then the cheapest resellers.
What GPT-5.5 Pro costs per month
Pick a workload close to yours or type your own volumes.
Independent benchmarks
Measured by third parties, not reported by OpenAI. Each links to its source and shows the date I checked it.
Benchmarks OpenAI reports (5)
- browsecomp (BrowseComp)90.1%
- hle-no-tools (Humanity's Last Exam (no tools))43.1%
- hle-with-tools (Humanity's Last Exam (with tools))57.2%
- frontiermath-tier-4 (FrontierMath Tier 4)39.6%
- gdpval (GDPval (wins or ties))82.3%
Labs pick their own settings and harnesses, so compare these only within one lab.
Supported request parameters
What you can set when you call GPT-5.5 Pro through an OpenAI compatible API.
- Tools
tools - Structured outputs
structured_outputs - Reasoning
reasoning
Alternatives to GPT-5.5 Pro
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Reads text, images and files. Tool calling, structured output, reasoning. Served by 27 providers.
by openaiSep 22, 2026$2/M input tokens$10/M output tokens27 providers
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Reads text, images and files. Tool calling, structured output, reasoning. Served by 2 providers.
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GPT-5.5 Pro questions
How much does the GPT-5.5 Pro API cost?
$30 per million input tokens and $180 per million output tokens. Prompts over 200K tokens bill at $60 input and $270 output. The estimator on this page turns that into a monthly bill for your own workload.
What is the context window of GPT-5.5 Pro?
1,050,000 tokens of input, and it can write up to 128,000 tokens in one reply. As a rough guide, a million tokens is around 750,000 English words.
Which providers serve GPT-5.5 Pro?
19 providers serve it, including Vercel AI Gateway, Poe and AIHubMix. The lowest input price is $27.27 per million tokens at Poe. Prices differ by host, so the Providers table on this page lists each one with its input and output price.
Does GPT-5.5 Pro support tool calling?
Yes. It accepts tool definitions and can return JSON that matches a schema, which is what an agent needs to call your APIs.
Is GPT-5.5 Pro open source?
No. OpenAI serves it through an API only, so you cannot download the weights or host it yourself.
When was GPT-5.5 Pro released?
Apr 8, 2026, with training data up to Dec 2025.
Catalog data from models.dev (MIT licensed), refreshed daily, last on Oct 15, 2026. Independent scores from my hand checked rankings, sources linked above. The summary is written from these facts.
Building on GPT-5.5 Pro?
I test your real tasks on it and the two closest alternatives, then ship the agent on whichever wins on cost and accuracy.
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