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News · OpenAI · 2 min read

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OpenAI expanded the GPT-6 family with GPT-6 Sol and low-cost GPT-6 Luna

On September 22, 2026, OpenAI released GPT-6 Sol and GPT-6 Luna, reasoning models with text and image input. Sol was priced at $2 input and $10 output per million tokens, and Luna at $0.10 and $0.50.

Archive entry: this covers an event from September 22, 2026, and we published it on November 8, 2026. The details come from sources dated at the time and may have changed since.

On September 22, 2026, OpenAI released GPT-6 Sol (gpt-6-sol) and GPT-6 Luna (gpt-6-luna), announced in Introducing GPT-6 Sol and Luna. Both were reasoning models with text and image input and text output, available in the Responses API and the Chat Completions API.

What changed

  • Sol pricing: $2 per 1M input tokens, $0.20 for cached input and $10 for output, for prompts up to 272K tokens.
  • Luna pricing: $0.10 per 1M input tokens, $0.01 for cached input and $0.50 for output, for prompts up to 272K tokens.
  • Codex and ChatGPT Work: per the ChatGPT and Codex changelog, both models rolled out to Plus, Pro, Business, Enterprise and Edu at lower token prices than their GPT-5.6 predecessors. They were available in Work and Codex, not in Chat.
  • Access: Free and Go users could reach Luna in the desktop app, Enterprise administrators had to enable the models, and Codex CLI users could select them with codex --model gpt-6-sol or gpt-6-luna.
  • GitHub Copilot: the GitHub changelog listed Sol as a balanced model for interactive and agentic coding on Pro+, Max, Business and Enterprise, and Luna as the lowest-cost option in the GPT-6 family on Pro and above.
  • Microsoft Foundry: the Microsoft Foundry roundup for September 2026 listed GPT-6 Luna as generally available on September 22, 2026, with a May 2026 knowledge cutoff.

What it meant for builders

Luna offered GPT-6-generation reasoning at a tenth of a dollar per million input tokens, which changed the economics of high-volume agents and subagents. Sol, at $2 input and $10 output, was the balanced option GitHub placed on its Pro+, Max, Business and Enterprise Copilot plans.

Fixes and related posts

On September 25, 2026, OpenAI fixed an image-encoding bug that had degraded image understanding in GPT-6 Sol and Luna. OpenAI also published a post titled Better prompt caching for GPT-6. The API release was also recorded in the OpenAI API changelog.

Sources

Written with AI assistance, strictly from the sources listed above. Before it went live, automated checks verified its dates, sources and every language edition.

OpenAI expanded the GPT-6 family with GPT-6 Sol and low-cost GPT-6 Luna | vibecoding.inc