GPT-5.5 Pro
Knows up to December 2025Missing 1,962 events
gpt-5.5-pro
$30 in, $180 out per 1M tokens
GPT-5.5
Model idgpt-5.5
Price$5 in, $30 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
4 ways to use GPT-5.5, with the model id each provider expects.
| Provider | Model id | Endpoint | Docs |
|---|---|---|---|
| OpenAI API | gpt-5.5 |
https://api.openai.com/v1/responses |
developers.openai.com |
| Azure OpenAI (Microsoft Foundry) | gpt-5.5 |
learn.microsoft.com | |
| OpenRouter | openai/gpt-5.5 |
openrouter.ai | |
| Web app | chatgpt.com |
Pricing
| Input | $5 per 1M tokens |
|---|---|
| Cached input | $0.50 per 1M tokens |
| Output | $30 per 1M tokens |
As published: “per 1M tokens (USD), standard tier”. Note: prompts >272K input tokens billed 2x input / 1.5x output.
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.
xhigh reasoning effort
Reasoning effort none/low/medium/high/xhigh.
1M context
1.05M context window with 128K output.
Four assistants, one scale
GPT-5.5 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 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 | December 2025 | 24 April 2026 | 93 | 1,962 |
Notes
Snapshot gpt-5.5-2026-04-23. Superseded by GPT-5.6 and GPT-6; still available.
curl https://api.openai.com/v1/responses \
-H "Authorization: Bearer $OPENAI_API_KEY" -H "Content-Type: application/json" \
-d '{"model":"gpt-5.5","input":"Hello"}'
Sources: