Highest-accuracy GPT-5.5 tier for slower, precision-heavy reasoning and coding
GPT-5.5 Pro by openai is offered by 19 providers on this page. Its official list price is $30.00 per 1M input tokens and $180 per 1M output tokens. The lowest paid channel is Poe at $27.27 / $164 per 1M, about 1.4× below the list price. That channel is a third-party gateway, so confirm its availability and rate limits before depending on it.
The context window is 1,050,000 tokens at the reference host, but hosts report different limits, from 400,000 to 1,050,000, so the usable window depends on the provider you pick. It supports reasoning, tool use, and structured output. Accepted input modalities are Text, Image, and PDF. Its training knowledge cuts off at 2025-12-01.
| Provider | Tier | Input | Output | Cache read | Cache write | Context | Output limit | Status |
|---|---|---|---|---|---|---|---|---|
| Poe | Gateway | $27.27 | $164 | — | — | 400,000 ⚠ | 128,000 | |
| Impossibl | Gateway | $30.00 tiered >272K: $60.00 | $180 | $3.00 | — | 1,050,000 | 128,000 | |
| OrcaRouter | Gateway | $30.00 tiered >272K: $60.00 | $180 | — | — | 1,050,000 | 100,000 | |
| Requesty | Gateway | $30.00 | $180 | — | — | 1,050,000 | 128,000 | |
| CrossModel | Gateway | $30.00 tiered >272K: $60.00 | $180 | — | — | 1,050,000 | 128,000 | |
| Vercel AI Gateway | Cloud | $30.00 | $180 | — | — | 1,000,000 ⚠ | 128,000 | |
| DevPass (LLM Gateway) | Gateway | $30.00 tiered >272K: $60.00 | $180 | — | — | 1,050,000 | 128,000 | |
| FastRouter | Gateway | $30.00 | $180 | — | — | 1,050,000 | 128,000 | |
| Cloudflare AI Gateway | Cloud | $30.00 | $180 | — | — | 1,000,000 ⚠ | 128,000 | |
| Opper | Gateway | $30.00 tiered >272K: $60.00 | $180 | — | — | 1,050,000 | 128,000 | |
| OpenAIOfficial | First-party | $30.00 tiered >272K: $60.00 | $180 | — | — | 1,050,000 | 128,000 | |
Sorted by blended price (input×0.75 + output×0.25) asc. The official channel always shows regardless of rank. Whether a gateway's low price is actually usable can't be verified.
| Name | Conditions | Score | Metric | Source |
|---|---|---|---|---|
| BrowseComp | — | 90.1 | accuracy | Source ↗ |
| Humanity's Last Exam | variant: no tools | 43.1 | accuracy | Source ↗ |
| Humanity's Last Exam | variant: with tools | 57.2 | accuracy | Source ↗ |
| FrontierMath | dataset: Tier 1-3 | 52.4 | accuracy | Source ↗ |
| FrontierMath | dataset: Tier 4 | 39.6 | accuracy | Source ↗ |
| GDPval | — | 82.3 | wins or ties | Source ↗ |
| GeneBench | — | 33.2 | accuracy | Source ↗ |
The same benchmark scores very differently across harness / dataset, so the qualifying conditions must be shown together.