OpenAI
GPT-5.5
GPT-5.5 is a OpenAI model with 1.05M context, $5 in / $30 out per million tokens, last verified September 3, 2026. Open weights: no. Public-board scores are linked to the publisher; vendor-only figures stay in the watch-out, not on the board.
GPT-5.5 is OpenAI's previous flagship — strong on Terminal-Bench 2.0 (82.7%) and 1M-token context.
Catalog record checked September 3, 2026Individual provider fields may change
| Specification | GPT-5.5 |
|---|---|
| Provider | OpenAI |
| Tier | Frontier |
| Context window | 1.05M |
| Max output | 128K |
| Input / 1M tokens | $5 |
| Output / 1M tokens | $30 |
| Weights | Closed |
| Parameters | Not disclosed |
| Reasoning levels | none, low, medium, high, xhigh, max |
| Modalities | text, image |
| API model id | gpt-5.5 |
| Released | April 23, 2026 |
Pricing tiers: Standard $5/$30 per MTok; >272K input billed 2x in / 1.5x out. Cached input $0.50/MTok; batch $2.50/$15.
Verified evidence
Published benchmark results
Each result keeps its source and measurement date visible. A missing benchmark is not treated as a zero.
| Benchmark | Score | Measured | Source |
|---|---|---|---|
| Artificial Analysis Intelligence Index [xhigh] | 58 | 2026-08-14 | Artificial Analysis · View source |
| SWE-bench Verified | 82.6 | 2026-09-01 | vals.ai SWE-bench Verified leaderboard (independent, mini-swe-agent bash-only); official SWE-bench not published · View source |
| Terminal-Bench 2.1 | 83.4 | 2026-07-27 | Kimi K3 model card (vendor-reported, xhigh, Codex harness; orig OpenAI) · View source |
| GPQA Diamond | 93.5 | 2026-07-27 | Kimi K3 model card (vendor-reported, xhigh); announcement charts show 93.6 — minor conflict preserved · View source |
| Humanity's Last Exam | 52.2 | 2026-04-23 | OpenAI — Introducing GPT-5.5 (vendor, with tools; 41.4 no tools) · View source |
Best for
- Reasoning
- Agentic coding
- Long-context work
Watch out
Source receipts
Catalog figures for this model were checked against the following sources.
- OpenAI — Introducing GPT-5.5 (accessed 2026-08-29)
- OpenAI API pricing (gpt-5.5 $5/$30) (accessed 2026-08-29)
Common questions
GPT-5.5
Answered from the verified figures on this page rather than general guidance.
How much does GPT-5.5 cost per million tokens?
GPT-5.5 is listed at $5 per million input tokens and $30 per million output tokens at standard rates. Output tokens usually dominate real bills, so weigh the output rate more heavily than the input rate. Standard $5/$30 per MTok; >272K input billed 2x in / 1.5x out. Cached input $0.50/MTok; batch $2.50/$15.
What is GPT-5.5's context window?
GPT-5.5 accepts about 1.05M tokens of context. That only matters if you routinely send very long documents, large codebases, or multi-turn histories that approach that limit.
What is GPT-5.5 best for?
GPT-5.5 is a frontier tier from OpenAI. It suits reasoning, agentic coding, long-context work. Superseded by GPT-5.6 Sol on quality; still a capable, widely integrated model.