GPT-5.5 Pro — API Pricing & Benchmarks
GPT-5.5 Pro is OpenAI's flagship reasoning model, released in 2026-04. The API costs $30.0 per 1M input tokens and $180.0 per 1M output tokens ($67.5 blended at a 3:1 ratio). It supports a 1.1M-token context window.
Explore provider routes and additional benchmark sources for GPT-5.5 Pro
| Provider | OpenAI |
| Input price / 1M tokens | $30.0 |
| Output price / 1M tokens | $180.0 |
| Cached input / 1M tokens | — |
| Blended price (3:1) | $67.5 |
| Context window | 1.1M |
| Max output tokens | 128K |
| Knowledge cutoff | 2025-12 |
| License | proprietary |
| Input modalities | T+I |
| Output speed (tok/s) | — |
| Released | 2026-04 |
| GPQA Diamond | 93.9%* |
| AIME | 100%* |
| Humanity's Last Exam | 57.2%* |
Where GPT-5.5 Pro fits
On a blended 3:1 basis GPT-5.5 Pro costs $67.5 per 1M tokens, cheaper than 0% of the 80 priced models in this index. As OpenAI's flagship it is aimed at the hardest workloads — complex reasoning, agentic coding and multi-step tool use — where output quality dominates cost.
Price history
| Period | Input $/1M | Output $/1M | Cached $/1M |
|---|---|---|---|
| 2026-07-18 → current | $30.0 | $180.0 | — |
No list-price changes recorded since tracking began. Full dataset: price-history.json (CC BY 4.0).
Alternatives at a similar price
- GPT-5.4 Pro (OpenAI) — $67.5/1M blended
- GPT-6 Astra (OpenAI) — $20.0/1M blended, AA Index 61.2
- Claude Fable 5.1 (Anthropic) — $20.0/1M blended, AA Index 65.7
- Claude Fable 5 (Anthropic) — $20.0/1M blended, AA Index 62.1
About OpenAI
OpenAI builds the GPT series. GPT-6 Astra (September 2026) sits at the top at $10/$50, and beneath it the GPT-5.6 generation ships in three sizes — Sol, Terra and Luna — that share the same 1.05M-token context window and tooling, so teams can move workloads between price points without changing integration code.