GPT-5.5
Knows up to December 2025Missing 1,962 events
gpt-5.5
$5 in, $30 out per 1M tokens
GPT-5.5 Pro
Hardest problems where latency does not matter.
Model idgpt-5.5-pro
Price$30 in, $180 out per 1M tokens
Checked29 September 2026
Knows up to December 2025
1,962events after its cutoff
85 historic, 449 major. 317 days of news.
It launched on 24 April 2026, already missing 93 of them.
How to call it
3 ways to use GPT-5.5 Pro, with the model id each provider expects.
| Provider | Model id | Endpoint | Docs |
|---|---|---|---|
| OpenAI API | gpt-5.5-pro |
https://api.openai.com/v1/responses |
developers.openai.com |
| OpenRouter | openai/gpt-5.5-pro |
openrouter.ai | |
| Web app | chatgpt.com |
Pricing
| Input | $30 per 1M tokens |
|---|---|
| Output | $180 per 1M tokens |
As published: “per 1M tokens (USD), no cached-input discount”.
Source: developers.openai.com, checked 29 September 2026.
Specs
- Input
- Text and images
- Output
- Text
- Context window
- 1,050,000 tokens
- Max output
- 128,000 tokens
- Open weights
- No
- Licence
- Proprietary
- Training cutoff
- December 2025
- Released
- 24 April 2026
- Status
- Legacy
- Type
- Reasoning model
What stands out
What its maker marketed at launch, and what people found later, each with its source.
Extended compute
Uses more compute per request; some requests take several minutes. Effort medium/high/xhigh.
Responses/Batch only
Not available on Chat Completions.
Four assistants, one scale
GPT-5.5 Pro is added as a fifth row. Each row runs from what the model knows (graphite) through the months between its cutoff and its launch (hatched) to today (pink).
- GPT-6 Astra 271 at launch, 1,863 today
- Claude Opus 5.5 372 at launch, 1,795 today
- Gemini 4 Hydrogen 1,863 at launch, 1,889 today
- Grok 4.7 387 at launch, 1,829 today
- GPT-5.5 Pro 93 at launch, 1,962 today
Show as a table
| Model | Cutoff | Released | Missing at launch | Missing today |
|---|---|---|---|---|
| GPT-6 Astra | April 2026 | 3 September 2026 | 271 | 1,863 |
| Claude Opus 5.5 | June 2026 | 22 September 2026 | 372 | 1,795 |
| Gemini 4 Hydrogen | March 2026 | 12 November 2026 | 1,863 | 1,889 |
| Grok 4.7 | May 2026 | 21 September 2026 | 387 | 1,829 |
| GPT-5.5 Pro | December 2025 | 24 April 2026 | 93 | 1,962 |
Notes
Last separately-billed “-pro” API id; for GPT-5.6/GPT-6 OpenRouter exposes pro as reasoning.mode pro. Snapshot gpt-5.5-pro-2026-04-23.
curl https://api.openai.com/v1/responses \
-H "Authorization: Bearer $OPENAI_API_KEY" -H "Content-Type: application/json" \
-d '{"model":"gpt-5.5-pro","input":"Hello"}'
Sources:
- https://developers.openai.com/api/docs/models/gpt-5.5-pro
- https://developers.openai.com/api/docs/pricing
- Models overview: https://developers.openai.com/api/docs/models
Not yet checked against an official source: Azure id not verified.