Published: 2026-09-23
Summary

GPT-6 Sol and Luna: where each one lives, what it costs, and which tier to point an agent at

Chapters / key moments (click to jump — plays here on the page)

The useful content here is routing and access, not capability. Sol and Luna are not more powerful than Astra — the video says so plainly — and the reason to care about them is that they cost half as much and burn through your plan's usage limits far more slowly.

Source video

"GPT-6 Sol + Luna Just Changed AI Agents" by Julian Goldie SEO — Watch on YouTube →

The three-tier split

Tier	Built for	List price / 1M tokens
GPT-6 Astra	Frontier results	Highest
GPT-6 Sol	Complex coding and professional work	$2 in / $10 out
GPT-6 Luna	Fast, efficient everyday work at scale	$0.10 in / $0.50 out

Both new tiers landed at roughly half the API price of the GPT-5.6 models they replace — Sol down from $4/$20, Luna down from $0.20/$1.20. Sol is also offered in light and medium sizes inside the ChatGPT Work model picker. Rates we track for all of these are in the cost calculator.

Where you can actually get them

ChatGPT Work and Codex — rolling out to Plus, Pro, Business, Enterprise and Edu. Rollout was gradual through the day, so a client that does not show the models yet is probably just waiting its turn rather than broken.
The API — available immediately.
Free and Go users — can try GPT-6 Luna in the desktop app. This is the no-cost route in.
In plain ChatGPT (outside the Work section) there are no tier dials — the model picker lives in Work.

Why this matters for agents

The stated reason to switch is that Astra exhausts plan usage limits quickly. Pointing routine agent work at Sol or Luna gets far more done on the same subscription. Both are also described as cheaper on long conversations thanks to better caching — which is exactly the shape of an agent's workload.

What actually improved, and what did not

The claimed wins: better performance on business tasks across apps, coding and computer use; Sol gets facts wrong about half as often as GPT-5.6; shorter answers with less jargon and more honesty about what was actually checked; and better caching for agents and long conversations.

The honest part, and the reason this page exists rather than a hype summary: he pulls up a third-party index and shows that the improvement is a mix of gains and regressions. Sol edges past GPT-5.6 Sol; Luna is roughly level with its predecessor. On that index Opus 5.5 sits at the top, ahead of Fable 5.1 and GPT-6 Astra Max. Treat any single index as one data point — see our aggregated leaderboard for the spread across sources.

Key Takeaways

Neither new tier is more capable than Astra. They are cheaper and easier on usage limits — route accordingly.
Luna in the desktop app is the free way to evaluate the new generation before committing.
Sol at $2/$10 is the sensible default for bulk agent work; keep Astra or Opus for the hard calls.
Better prompt caching makes these tiers disproportionately cheaper for long-running agent sessions.
A staged rollout means "my client does not list it" is usually a timing problem, not a configuration one.

Measured head-to-heads against these models: Opus 5.5 vs Sol and Opus 5.5 vs Astra.