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A small pale quartz half-moon resting on a dark slate block on a dark background, abstract hero artwork for GPT 5.6 Luna

OpenAI

GPT 5.6 Luna

OpenAI's fastest, most affordable GPT-5.6 model for quick chat and high-volume work.

Chat with GPT 5.6 Luna in Super AgentView pricing

What is GPT 5.6 Luna?

GPT 5.6 Luna is the fastest and most affordable model in OpenAI's GPT-5.6 series, generally available since July 9, 2026.

OpenAI built it for cost-sensitive, high-volume work and says it roughly fills the nano tier of earlier GPT-5 families. OpenAI is rolling it out as the default ChatGPT model for Free and Go users. Like the rest of the series, it takes text and images in a 1.05M-token context window. GPT-6 Luna, Super Agent's default model, is its newer counterpart.

Provider
OpenAI
Context window
1.05M tokens
Input
Text, Image
Reasoning
Off to max
Max output
128K tokens
Knowledge cutoff
Feb 16, 2026
Released
Jul 9, 2026

How GPT 5.6 Luna performs

Published by OpenAI

Results OpenAI reported for GPT 5.6 Luna. Each lab runs its own setup, so compare these with other models only inside the same table.

Benchmark results OpenAI published for GPT 5.6 Luna
BenchmarkScoreSetting
Agents' Last Exam50.3%
SWE-Bench Pro62.7%
DeepSWE v1.167.2%
Terminal-Bench 2.184.7%
OSWorld 2.045.6%
BrowseComp83.3%
GPQA Diamond92.3%
MMMU Pro78.4%no tools
Toolathlon53.4%
OpenAI MRCR v2, 8 needles41.3%512K to 1M tokens

Source: openai.com

What you can do with GPT 5.6 Luna

  • Fastest, lowest-cost tier of the GPT-5.6 series

  • Becoming the default ChatGPT model for Free and Go users

  • Reasoning off for instant answers, up to max when needed

  • Same 1.05M-token window and image input as the rest of GPT-5.6

How to prompt GPT 5.6 Luna

  • Keep requests short and specific for the fastest answers.
  • Turn reasoning off when you just need variations or rewrites.
  • For harder tasks, try GPT 5.6 Terra or GPT 5.6 Sol.

Where GPT 5.6 Luna fits best

  • Quick chat

  • Sorting and labeling lists

  • Short prompt variations

  • Simple agent steps

How GPT 5.6 Luna compares

GPT 5.6 Luna compared with other chat models on Flashloop
ModelLMArena textLMArena codingContext windowReasoning
GPT 5.6 Luna1453#751502#761.05M tokensOff to max
Gemini 3.5 Flash Lite1455#711502#771M tokensLow, medium, high
Grok 4.61456#661510#60500K tokensLow to extra high
DeepSeek V4 Pro1458#641501#791M tokensOff, medium, high, extra high
GPT-6 Sol1459#621519#381.05M tokensOff to max

Good to know before you start

  • GPT-6 Luna is the newer light model from OpenAI
  • Not built for the hardest reasoning work
  • Text replies only; ask Super Agent for an image or clip and a Flashloop generation model renders it

Start chatting with GPT 5.6 Luna

Chat with GPT 5.6 Luna in Super Agent

  1. Select GPT 5.6 Luna

    Open Super Agent on Flashloop and choose GPT 5.6 Luna in the model picker.

  2. Enter your prompt

    Ask for what you need: an answer, a plan, or the images and videos you want the agent to make.

  3. Send and keep going

    Send the message. GPT 5.6 Luna answers in Super Agent and runs any generations you asked for.

Questions about GPT 5.6 Luna

What is GPT 5.6 Luna used for?

OpenAI built it for cost-sensitive, high-volume work and is rolling it out as ChatGPT's default model for Free and Go users.

How does GPT 5.6 Luna compare with GPT-6 Luna?

GPT-6 Luna is OpenAI's newer light model and the default in Super Agent. GPT 5.6 Luna is the previous generation's equivalent.

Which reasoning levels does GPT 5.6 Luna support?

Off, low, medium, high, extra high and max. Super Agent starts it at low.

Where is GPT 5.6 Luna in the model picker?

Under All models.

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