GPT-6.1 Sol vs Astra vs Luna — and the GPT-6 Sol it replaces

Prices per 1M tokens — GPT-6.1 Sol vs GPT-6 Astra and GPT-6 Luna (Sept 2026)
	GPT-6 Astra	GPT-6.1 Sol ⭐	GPT-6 Luna
Position	Flagship, best results	Near-Astra at 1/5 price	Fast, cheap, everyday scale
Input / 1M	$10	$2	$0.10
Output / 1M	$50	$10	$0.50
Cached / 1M	$1	$0.10	$0.01
Best for	Hardest research tasks	Agents, coding, office work	High-volume simple work

Where’s GPT-6 Sol? OpenAI shipped it only about 7 days before 6.1 Sol, which supersedes it. Since 6 Sol is no longer the tier to buy, the table lists the three current models with published prices; 6 Sol comparisons remain in the benchmarks.

Simple rule

Default to 6.1 Sol — it replaced GPT-6 Sol (OpenAI launched it only 7 days after GPT-6 Sol).
Use Astra only for the hardest scientific work (it still leads Terminal-Bench Science at 68.1%).
Use Luna when volume matters more than brains (20× cheaper input than Sol).

Sources: OpenAI announcement. See full pricing and benchmarks.