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OpenAI

GPT-5.1-Codex-Mini

openai/gpt-5.1-codex-mini

$0.275 in · $2.20 out per 1M tokens400k contextNov 13, 2025

about 0.1¢ a message

A typical message: about 500 tokens you send and 500 it writes.

Chat with GPT-5.1-Codex-Mini
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Spec sheet

Published facts from the catalog, billed prices and what we measured here. Anything not measured says so.

Price, billed here

Input, per 1M tokens
$0.275provider $0.25
Output, per 1M tokens
$2.20provider $2.00
Cached input, per 1M
$0.033provider $0.03
Margin
+10%

Context and formats

Context window
400,000 tokens
Longest answer
128,000 tokens
Reads
text and images
Makes
text
First listed
2025-11-13

Measured here, last 7 days

First token, median
not measured
Answered without error
not measured

Tools and JSON

Tool calling
declaredthe provider's claim, not yet measured here
JSON output
declaredthe provider's claim, not yet measured here

Price and latency history as JSON: GET /api/planet/history?id=openai/gpt-5.1-codex-mini.

About

GPT-5.1-Codex-Mini is a smaller and faster version of GPT-5.1-Codex

In OpenAI's words.

Try it here

The answer appears here.

Measured here

Call it

Use one OpenAI compatible endpoint, this model's id and an am_live_ key from the dashboard. You can also try it in chat first with no key.

curl https://useantimatter.com/v1/chat/completions \
  -H "Authorization: Bearer $ANTIMATTER_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"model": "openai/gpt-5.1-codex-mini", "messages": [{"role": "user", "content": "Hello"}]}'

Everything else is in the docs.

Embed this

A badge showing this model's live price per million tokens, as billed here, for a README or a site. It links back to this page.

GPT-5.1-Codex-Mini price on Antimatter
<a href="https://useantimatter.com/planet/openai/gpt-5.1-codex-mini"><img src="https://useantimatter.com/api/badge/price?id=openai%2Fgpt-5.1-codex-mini" alt="GPT-5.1-Codex-Mini price on Antimatter" height="28"></a>

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