OpenAI today launched GPT-6 Sol and GPT-6 Luna, two new models that succeed GPT-6 Astra. OpenAI claims that the new models were developed using methods similar to those of Astra to improve professional work, factuality, coding, computer use and alignment.
GPT-6 Sol is intended for everyday work and costs less than Astra. GPT-6 Luna is an even cheaper model. Luna is optimized for quick responses and higher volume, while Sol has more reasoning ability.
The new models outperform their predecessors in OpenAI’s benchmark tests, and GPT-6 Sol makes “about half as many errors” as GPT-5.6 Sol. GPT-6 Sol shows improvements in coding and computer usage compared to GPT-5.6 Sol, and it matches or beats Claude Fable 5.1’s scores on some tests.
OpenAI compared GPT-6 Sol to Opus 5 on several tests, but Anthropic today released a new Opus 5.5 model that outperforms Astra on some coding and knowledge work tests.
GPT-6 Sol and Luna adopt the improved OpenAI communication style introduced with Astra for streamlined conversations with less jargon and fewer low-value details. Answers should be slightly shorter without losing substance, and new models have lower rates of misleading claims about their coding work in OpenAI’s alignment tests.
OpenAI is reducing token prices for Sol and Luna compared to their 5.6 counterparts, and fast caching has been improved. OpenAI claims that agents will reuse more context, respond faster, and benefit from 90% reductions on reads of cached input tokens.
GPT-6 Sol is priced at $2 per million input tokens and $10 per million output tokens, a cut in half. GPT-6 Luna costs $0.10 per million input tokens and $0.50 per million output tokens, compared to $0.20 and $1.20, respectively. GPT-6 Sol costs half as much per token as Opus 5.5, but Anthropic says Opus 5.5 uses fewer tokens per task than Opus 5, so it’s not a direct comparison.
GPT-6 Sol and GPT-6 Luna are rolling out to ChatGPT Work and Codex starting today for Plus, Pro, Business, Enterprise, and Edu users. GPT-6 Luna is available to Free and Go users in the desktop app. GPT–6 Sol and Luna are not yet available in Chat mode.
