How much cheaper is GPT-6 Sol than GPT-5.6 Sol?

GPT-6 Sol costs exactly half. OpenAI lists it at $2.00 per million input tokens and $10.00 per million output, where GPT-5.6 Sol is $4.00 and $20.00. GPT-6 Luna follows the same pattern at $0.10 and $0.50 against GPT-5.6 Luna's $0.20 and $1.20. Cached input on GPT-6 Sol is $0.20 per million tokens and on Luna $0.01.

Which one should I pick, GPT-6 Sol or GPT-6 Luna?

OpenAI positions GPT-6 Sol as the balanced choice for interactive and agentic coding and development work that needs careful, multistep validation. GPT-6 Luna is the lightweight, cost-efficient option for smaller and faster tasks — summarizing a document, extracting fields, answering a short question. Luna is the lowest-cost model in the GPT-6 family.

Can I get GPT-6 Sol and Luna in GitHub Copilot?

Yes, GitHub added both on the same day. GPT-6 Sol is available to Copilot Pro+, Max, Business, and Enterprise plans, and GPT-6 Luna to Copilot Pro, Pro+, Max, Business, and Enterprise. GitHub is rolling them out gradually across Visual Studio Code, Visual Studio, the Copilot CLI, the cloud agent, github.com, mobile, JetBrains, Xcode, and Eclipse.

How do the new tiers compare with GPT-6 Astra?

GPT-6 Astra stays the top tier and the most expensive at $10.00 input and $50.00 output per million tokens. Sol and Luna share Astra's 1.05M-token context window and 128K-token output limit, so the difference is capability and price rather than how much they can read. OpenAI says GPT-6 Sol reaches Astra-level reliability at much lower cost.

Are GPT-6 Sol and Luna in ChatGPT, or only the API?

Both. Sol and Luna are in ChatGPT Work, Codex, and the ChatGPT API, and Luna additionally reaches the desktop app and Free and Go users. OpenAI expected the rollout across the ChatGPT app and website to continue through release day, so the models may appear in the picker at different times for different accounts.

OpenAI · 2026-09-22 · major

GPT-6 Sol and Luna — OpenAI's mid and low tiers at half the 5.6 price

GPT-6 Sol and GPT-6 Luna fill out OpenAI's GPT-6 family below Astra. Sol costs $2 in and $10 out per million tokens, Luna $0.10 and $0.50 — half the GPT-5.6 rates. Both carry a 1.05M-token context window.

Close-up of the ChatGPT app icon glowing on a dark phone screen — TechCrunch / Getty Images

OpenAI fills in the GPT-6 family below Astra with a balanced tier and a cheap one, both at half the price of their 5.6 predecessors.

Quick facts

Maker	OpenAI
Model ids	gpt-6-sol, gpt-6-luna
Context window	1.05M tokens
Max output	128K tokens
Price (Sol)	$2 in / $10 out per 1M tokens
Price (Luna)	$0.10 in / $0.50 out per 1M tokens
Availability	API, Codex, ChatGPT, GitHub Copilot

Pricing

GPT-6 Sol input · Cached input $0.20	$2.00 / 1M tokens
GPT-6 Sol output	$10.00 / 1M tokens
GPT-6 Luna input · Cached input $0.01	$0.10 / 1M tokens
GPT-6 Luna output	$0.50 / 1M tokens
GPT-6 Astra input · The top GPT-6 tier, for comparison	$10.00 / 1M tokens
GPT-6 Astra output	$50.00 / 1M tokens

source ↗

What is it?

Two cheaper tiers join the GPT-6 family: GPT-6 Sol, a balanced model for interactive and agentic coding, and GPT-6 Luna, the lowest-cost option, aimed at smaller jobs such as summarizing documents, pulling out information, and answering quick questions. Until now GPT-6 meant only Astra, the top tier at $10 and $50 per million tokens. Both new models share Astra's 1.05M-token context window and 128K-token maximum output.

How does it work?

The pricing is where the generational change shows up. Sol is listed at $2.00 per million input tokens and $10.00 per million output, against $4.00 and $20.00 for GPT-5.6 Sol; Luna is $0.10 and $0.50, against $0.20 and $1.20. Cached input is a tenth of the input rate on both, and requests that run past the short-context limit are billed at the higher long-context rates. Knowledge cutoffs differ slightly — April 20, 2026 for Sol, May 18, 2026 for Luna.

Why does it matter?

Cost is what usually decides which model an agent loop or a batch job actually runs on, and this halves it for the two tiers that do most of that work. OpenAI says GPT-6 Sol makes about half as many mistakes as its predecessor and reaches Astra-level reliability at much lower cost. The rollout is broad: both models are in the API, Codex, and ChatGPT Work, Luna also reaches the desktop app and Free and Go users, and GitHub shipped both to Copilot the same day — Sol on Pro+, Max, Business, and Enterprise, Luna on Pro as well.

Who is it for?

developers running agent loops and high-volume API jobs

Frequently asked questions

How much cheaper is GPT-6 Sol than GPT-5.6 Sol?: GPT-6 Sol costs exactly half. OpenAI lists it at $2.00 per million input tokens and $10.00 per million output, where GPT-5.6 Sol is $4.00 and $20.00. GPT-6 Luna follows the same pattern at $0.10 and $0.50 against GPT-5.6 Luna's $0.20 and $1.20. Cached input on GPT-6 Sol is $0.20 per million tokens and on Luna $0.01.
Which one should I pick, GPT-6 Sol or GPT-6 Luna?: OpenAI positions GPT-6 Sol as the balanced choice for interactive and agentic coding and development work that needs careful, multistep validation. GPT-6 Luna is the lightweight, cost-efficient option for smaller and faster tasks — summarizing a document, extracting fields, answering a short question. Luna is the lowest-cost model in the GPT-6 family.
Can I get GPT-6 Sol and Luna in GitHub Copilot?: Yes, GitHub added both on the same day. GPT-6 Sol is available to Copilot Pro+, Max, Business, and Enterprise plans, and GPT-6 Luna to Copilot Pro, Pro+, Max, Business, and Enterprise. GitHub is rolling them out gradually across Visual Studio Code, Visual Studio, the Copilot CLI, the cloud agent, github.com, mobile, JetBrains, Xcode, and Eclipse.
How do the new tiers compare with GPT-6 Astra?: GPT-6 Astra stays the top tier and the most expensive at $10.00 input and $50.00 output per million tokens. Sol and Luna share Astra's 1.05M-token context window and 128K-token output limit, so the difference is capability and price rather than how much they can read. OpenAI says GPT-6 Sol reaches Astra-level reliability at much lower cost.
Are GPT-6 Sol and Luna in ChatGPT, or only the API?: Both. Sol and Luna are in ChatGPT Work, Codex, and the ChatGPT API, and Luna additionally reaches the desktop app and Free and Go users. OpenAI expected the rollout across the ChatGPT app and website to continue through release day, so the models may appear in the picker at different times for different accounts.

Try it

Call model id gpt-6-sol or gpt-6-luna in the OpenAI API