Last refreshed 2026-06-19. Next refresh: weekly.
Why use GPT-5.5 Instant on OpenAI API?
OpenAI API offers GPT-5.5 Instant with pay-as-you-go pricing at $5.00/1M input tokens. OpenAI is a leading AI research and deployment company dedicated to developing safe and beneficial artificial general intelligence (AGI) for humanity.
Setup recipe
Python + curlpip install openaiexport OPENAI_API_KEY=...import os
from openai import OpenAI
client = OpenAI() # reads OPENAI_API_KEY from env
response = client.chat.completions.create(chat-latestRequest example
import os
from openai import OpenAI
client = OpenAI() # reads OPENAI_API_KEY from env
response = client.chat.completions.create(
model="chat-latest",
messages=[{"role": "user", "content": "Hello"}]
)
print(response.choices[0].message.content)Gotchas
- Use provider model ID "chat-latest", not the LLMReference slug "gpt-5.5-instant".
- Use the model slug directly, e.g. "gpt-4o" or "gpt-4.1-mini".
- The examples expect OPENAI_API_KEY; rename it only if your application config maps the new variable.
Pricing
| Type | Price (per 1M) |
|---|---|
| Input tokens | $5.00 |
| Output tokens | $30.00 |
Capabilities
About GPT-5.5 Instant
GPT-5.5 Instant is OpenAI's latest Instant model used in ChatGPT, released May 5, 2026 as the new default ChatGPT model and exposed in the API as chat-latest. OpenAI says the update improves factuality, image analysis, STEM answers, web-search decisions, personalization from past chats/files/connected Gmail, and concise conversational style. OpenAI reports 52.5% fewer hallucinated claims than GPT-5.3 Instant on high-stakes prompts and 37.3% fewer inaccurate claims on difficult conversations flagged for factual errors.
FAQ
What does GPT-5.5 Instant cost on OpenAI API?
On OpenAI API, GPT-5.5 Instant costs $5.00 per 1M input tokens and $30.00 per 1M output tokens.
What is the context window for GPT-5.5 Instant on OpenAI API?
GPT-5.5 Instant supports a 400k token context window on OpenAI API.
What API model ID do I use for GPT-5.5 Instant on OpenAI API?
Use the model ID chat-latest when calling OpenAI API's API.
Who created GPT-5.5 Instant?
GPT-5.5 Instant was created by OpenAI as part of the GPT-5.5 model family.
Is GPT-5.5 Instant open source?
GPT-5.5 Instant is not open source; the seed data lists it as proprietary.