Using GPT-5.1 Codex Mini on OpenAI API

Quick Start

1. 1
   Create an account at OpenAI API and generate an API key.
2. 2
   Use the OpenAI API SDK or REST API to call gpt-5.1-codex-mini — see the documentation for request format.
3. 3
   You'll be billed $0.25/1M input, $2.00/1M output tokens. See full pricing.

Code Examples

import os
from openai import OpenAI

client = OpenAI()  # reads OPENAI_API_KEY from env
response = client.chat.completions.create(
    model="gpt-5.1-codex-mini",
    messages=[{"role": "user", "content": "Hello"}]
)
print(response.choices[0].message.content)

Pricing on OpenAI API

Capabilities

About GPT-5.1 Codex Mini

GPT-5.1 Codex Mini is a smaller, faster, and more cost-efficient agentic coding model in the GPT-5.1 Codex lineup. Delivers approximately 4x more usage within ChatGPT subscriptions compared to GPT-5.1 Codex Max at a slight capability tradeoff. Priced at $0.25 per 1M input tokens and $2 per 1M output tokens via API. Available in the Codex CLI and IDE extension, where it is offered automatically when users approach their usage limit.