Codex vs GPT-5.1

OpenAI vs OpenAI — benchmarks, pricing, and capabilities side by side.

	Codex	GPT-5.1
Intelligence index	—	89
Developer	OpenAI	OpenAI
Type	LLM	LLM
Access	API only	API only
Context window	—	400,000 tokens
Input price	—	$1.25 / 1M
Output price	—	$10.00 / 1M
Speed	—	115 tok/s
Released	August 10, 2021	November 12, 2025
Parameters	—	—
Input modalities	Text	Text, Image
Output modalities	Text	Text

Codex details GPT-5.1 details