GPT-5.1-Codex-Max | Epoch AI

ECI

N/A

OpenAI

Nov. 19, 2025

Closed weights

GPT-5.1-Codex-Max is a closed-weights model from OpenAI, released November 19, 2025.

GPT-5.1-Codex-Max vs select alternatives

Domain	Benchmark	GPT-5.1-Codex-Max OpenAI Nov. 19, 2025 Closed weights	Gemini 3 Pro Google DeepMind Nov. 18, 2025 Closed weights	Claude Sonnet 4.5 Anthropic Sep. 29, 2025 Closed weights	Grok 4 xAI Jul. 9, 2025 Closed weights
Mathematics	ProofBenchBest score 100%	9%	20%	19%	n/a
Software engineering	METR Time HorizonsBest score 17 hr 25 min	3 hr 44 min	3 hr 44 min	2 hr 2 min	1 hr 50 min
	ALE-BenchBest score 2951	1209	1177	796	—
	Terminal-Bench 2.0Best score 85%	60%	69%	47%	27%

Model metadata

General
Organization	OpenAI
Release date	Nov. 19, 2025
Model accessibility	Closed weights
Country	United States of America
Knowledge cutoff	Unknown
Provider notes	Building more with GPT-5.1-Codex-Max

Pricing
Input price	$1.25 / 1M tokens
Output price	$10 / 1M tokens

Training
Parameters	Unknown
Training compute	Unknown
Training hardware	Unknown
Training time	Unknown
Training dataset size	Unknown