GPT-5.6 Sol | Epoch AI

ECI#11

163

OpenAI

Jul. 9, 2026

Closed weights

GPT-5.6 Sol is a closed-weights model from OpenAI, released July 9, 2026. It has an ECI score of 163 and ranks 11th of 253 tracked models. At the time of its release, it ranked 3rd of 220 tracked models.

GPT-5.6 Sol vs select alternatives

Domain	Benchmark	GPT-5.6 Sol OpenAI Jul. 9, 2026 Closed weights	GPT-5.5 Pro OpenAI Apr. 23, 2026 Closed weights	Claude Fable 5 Anthropic Jun. 9, 2026 Closed weights	Gemini 3.1 Pro Google DeepMind Feb. 19, 2026 Closed weights
	ECI scoreBest score 169	163	163	163	155
	Ranking	#11	#10	#9	#35
Games	Chess PuzzlesBest score 76%	68%	62%	47%	51%
	Earthborne Rangers (EBR-bench)Best score 76%	45%	n/a	40%	14%
	Mystery Game PuzzlesBest score 84%	58%	n/a	52%	34%
Mathematics	FrontierMath ErdősBest score 4%	0%	n/a	0%	n/a
	FrontierMath Tiers 1-3 (v2)Best score 94%	89%	88%	87%	60%
	FrontierMath Tier 4 (v2)Best score 100%	83%	78%	90%	27%
Multimodal	Furniture Assembly BenchmarkBest score 83%	57%	n/a	36%	27%
Software engineering	MirrorCodeBest score 77%	20%	n/a	64%	9%
World knowledge	SimpleQA VerifiedBest score 76%	70%	n/a	71%	74%

Model metadata

General
Organization	OpenAI
Release date	Jul. 9, 2026
Model accessibility	Closed weights
Country	United States of America
Knowledge cutoff	Unknown
Provider notes	GPT-5.6

Pricing
Input price	$4 / 1M tokens
Output price	$20 / 1M tokens

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