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GPT-6 Luna
OpenAI · GPT-6
OpenAI released GPT-6 Luna on September 22, 2026.
GPT-6 Luna is the small, low-cost OpenAI reasoning model released on September 22, 2026 alongside GPT-6 Sol. It accepts text and image input and generates text through the Responses and Chat Completions APIs, and reached Codex and ChatGPT Work the same day. Standard pricing for prompts up to 272K input tokens is $0.10 per million input tokens, $0.01 cached input and $0.50 output, a twentieth of GPT-6 Sol's price. On September 25 OpenAI fixed an image encoding bug that had degraded image understanding in Luna and Sol, and recommended rerunning image-based evaluations.
GPT-6 Luna at a glance
- Released
- API model id
gpt-6-luna- Available on
- OpenAI APICodexChatGPT Work
- Previous model
- GPT-5.6 (July 9, 2026)
- Announcement
- developers.openai.com
What changed from GPT-5.6
GPT-6 Luna replaces GPT-5.6 Luna as OpenAI's efficient tier for high-volume workloads, now as a GPT-6 reasoning model with image input.
New to model names and version numbers? Read how AI labs version their models.
GPT-6 Luna release timeline
The launch and every later OpenAI release that mentions GPT-6 Luna, oldest first.
- Released GPT-6 Sol and GPT-6 Luna
Released GPT-6 Sol (gpt-6-sol) and GPT-6 Luna (gpt-6-luna). These reasoning models accept text and image inputs and generate text through the Responses and Chat Completions APIs. Standard pricing per 1M tokens for prompts with up to 272K input tokens: GPT-6 Sol: $2 input, $0.20…
Source: OpenAI API Changelog - GPT-6 Sol and GPT-6 Luna in Codex and ChatGPT Work
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. Select with /model or codex --model gpt-6-sol / gpt-6-luna.
Source: Codex Changelog - Image encoding fix for GPT-6 Sol and GPT-6 Luna
Fixed a bug in image encoding that degraded image understanding in GPT-6 Sol and GPT-6 Luna. This update improves results on visual tasks in the API and Codex, including computer use. If your use cases involve image inputs, we recommend rerunning your evaluations and retrying wo…
Source: OpenAI API Changelog - Decisions API Beta Release
Released the Decisions API in beta with gpt-6-luna. Turn text and images into typed answers 10x faster than the Responses API.
Source: OpenAI API Changelog - Decisions API General Availability
The Decisions API is now generally available with gpt-6-luna. Cache shared input across requests for prompt-cache discounts, include images in individual question instructions, and pass structured data directly with input_json.
Source: OpenAI API Changelog
GPT-6 Luna FAQ
When was GPT-6 Luna released?
OpenAI released GPT-6 Luna on September 22, 2026. The launch entry below links to the official announcement.
Where is GPT-6 Luna available?
GPT-6 Luna is available on OpenAI API, Codex and ChatGPT Work. Later availability changes are listed under follow-up releases on this page.
What is the GPT-6 Luna API model id?
Use gpt-6-luna in OpenAI's API.
What came before GPT-6 Luna?
GPT-6 Luna follows GPT-5.6, released on July 9, 2026.
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