GPT-5.5 Pro | Epoch AI

ECI#6

162

OpenAI

Apr. 23, 2026

Closed weights

GPT-5.5 Pro is a closed-weights model from OpenAI, released April 23, 2026. It has an ECI score of 162 and ranks 6th of 253 tracked models. At the time of its release, it ranked 1st of 209 tracked models.

GPT-5.5 Pro vs select alternatives

Domain	Benchmark	GPT-5.5 Pro OpenAI Apr. 23, 2026 Closed weights	GPT-5.4 Pro OpenAI Mar. 5, 2026 Closed weights	Claude Opus 4.7 Anthropic Apr. 16, 2026 Closed weights	Gemini 3.1 Pro Google DeepMind Feb. 19, 2026 Closed weights
	ECI scoreBest score 167	162	159	156	155
	Ranking	#6	#11	#22	#31
Conceptual reasoning	SimpleBenchBest score 82%	77%	74%	62%	80%
	ARC-AGI-2Best score 95%	85%	83%	76%	77%
	ARC-AGI-1Best score 99%	97%	95%	94%	98%
Games	Chess PuzzlesBest score 72%	64%	59%	30%	55%
Mathematics	FrontierMath Tiers 1-3 (v2)Best score 94%	88%	82%	70%	60%
	FrontierMath Tier 4 (v2)Best score 100%	78%	59%	32%	27%
	OTIS Mock AIME 2024-2025Best score 100%	100%	n/a	98%	96%
Science	CritPtBest score 32%	31%	30%	12%	18%
	GPQA DiamondBest score 96%	94%	95%	90%	94%

Model metadata

General
Organization	OpenAI
Release date	Apr. 23, 2026
Model accessibility	Closed weights
Country	United States of America
Knowledge cutoff	Unknown
Provider notes	Introducing GPT‑5.5

Pricing
Input price	$30 / 1M tokens
Output price	$180 / 1M tokens

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