OpenAI upgrading ChatGPT and Codex with two more GPT-6 models

Earlier this month, OpenAI released the first GPT-6 model with Astra. Now GPT-6 is expanding with new GPT-6 Sol and GPT-6 Luna models.

GPT-6 Sol and GPT-6 Luna are now available

Per the ChatGPT desktop app release notes, GPT-6 Sol and GPT-6 Luna will use fewer tokens to run than GPT-5.6 versions of the same class model.

GPT-6 Sol and GPT-6 Luna are rolling out to Codex and ChatGPT Work at lower token prices than their GPT-5.6 predecessors. Use Sol for complex coding and agentic workflows, and Luna for focused, high-volume tasks.

Both models are rolling out to Plus, Pro, Business, Enterprise, and Edu users. Free and Go users can access Luna in the desktop app. Availability depends on rollout and workspace settings; Enterprise administrators must enable the new models. In ChatGPT, the models are available in Work and Codex, but not Chat.

Note the absence of a GPT-6 Terra model. It’s expected that OpenAI is dropping the medium model in favor of just three: Terra (small), Sol (large), and Astra (extra large).

Here’s the official announcement from OpenAI:

While the most demanding and important projects still call for Astra’s full depth, work happens at different scales, rhythms, and budgets.

That’s why we’re expanding the GPT‑6 universe with GPT‑6 Sol and GPT‑6 Luna. GPT‑6 Astra introduced a new generation of intelligence—these models help distribute the benefits of that intelligence by advancing the frontier on cost efficiency. We trained GPT‑6 Sol and Luna with similar methods as GPT‑6 Astra, bringing the advances behind Astra’s state-of-the-art performance in professional work, factuality, coding, computer use, and alignment to faster, more affordable models.

The company describes its two newest models as more capable than the GPT-5.6 versions as well as more affordable than Astra (and the GPT-5.6 versions they replace). For instance, the GPT-6 versions of Sol and Luna are 50% cheaper than the GPT-5.6 versions.

The GPT‑6 models lead across the cost–intelligence curve, combining exceptional capabilities at every tier with infrastructure that delivers them efficiently at scale. Improvements in caching and inference let us serve these models at lower cost, and we’re passing those savings directly on to users and customers by reducing API prices for Sol and Luna by 50% compared with their GPT‑5.6 promotional pricing. Together, these improvements make advanced AI practical for more everyday tasks and applications at scale.

In terms of coding, this is what OpenAI says about its new models:

This year, coding agents have begun tackling tasks with more complexity, scope, and duration than ever before. At OpenAI, our internal usage has grown exponentially. Valued at API prices, daily token usage has exceeded $600 for the median researcher and $7,000 for researchers at the 90th percentile (Research acceleration: The view inside OpenAI⁠). As coding agents take on longer and more demanding tasks, the cost of sustained use matters more. GPT‑6 Sol and Luna combine strong coding performance with lower API prices, giving developers more room to iterate and teams the confidence to be more ambitious about what they ask Codex to take on.

ChatGPT also excels at Computer Use, and these new models continue that push:

While GPT‑6 Astra remains the world’s best model for computer use, GPT‑6 Sol and Luna offer more cost-efficient performance than their predecessors. On OSWorld 2.0 offline, GPT‑6 Sol at xhigh effort achieves a similar score to Claude Opus 5 at medium effort—60.5% versus 60.3%—at approximately 80% lower cost per task. GPT‑6 Luna (max) is able to exceed GPT‑5.6 Sol (medium) at one tenth of its cost.

In terms of availability, OpenAI says both new models will be rolling out throughout the day.

GPT‑6 Sol and GPT‑6 Luna are available in ChatGPT Work and Codex starting today for all Plus, Pro, Business, Enterprise, and Edu users. Free and Go users can access GPT‑6 Luna in the desktop app. 

You can learn much more about the new models here.

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