Skip to content
chatmodel
Try now
OpenAI logo

Chat model · OpenAI

OpenAI GPT 5.6 Luna

Included in Pro · came out July 2026

Light, quick help with the day's small questions

GPT 5.6 Luna is the lighter model in OpenAI's GPT 5.6 line. It suits everyday questions you want answered quickly, from a recipe swap to a short reply.

Chat with OpenAI GPT 5.6 Luna

OpenAI GPT 5.6 Luna in numbers

What it knows about

Up to February 2026

It learned from information up to February 2026. For anything newer it can search the web and show you where it found it.

What you can give it

  • Your wordsYes
  • PhotosYes
  • PDFs and filesYes
  • The webYes

Real answers

See how OpenAI GPT 5.6 Luna answers

We asked it the same everyday questions as every other model in chatmodel, one try each. This is exactly what came back.

My neighbour watered my plants for two weeks while I was away. Write a short, warm thank-you note I can leave with a small gift. Keep it under 80 words.

Dear [Neighbor’s Name],

Thank you so much for watering my plants while I was away. I really appreciate your kindness and care—you helped keep everything green and thriving! Please enjoy this small gift as a token of my gratitude.

Warmly,
[Your Name]

Answered in about 2 seconds · 42 words

Ask it yourself

The GPT family in chatmodel

The newest is OpenAI GPT 6 Astra. Ordered by release date.

  1. March 2026OpenAI GPT 5.4
  2. March 2026OpenAI GPT 5.4 Mini
  3. April 2026OpenAI GPT 5.5
  4. July 2026OpenAI GPT 5.6 Sol
  5. July 2026OpenAI GPT 5.6 Terra
  6. July 2026OpenAI GPT 5.6 LunaYou're here
  7. September 2026NewestOpenAI GPT 6 Astra

What it's good for

Try it with one of these

Press “Try this” and chatmodel opens with OpenAI GPT 5.6 Luna selected and the message already written. Change any word you like.

Replace an ingredient

“My recipe needs buttermilk and I don't have any. What can I use instead, and how much for 250 ml?”

Try this

Reply to the landlord

“Write a short, polite reply to my landlord saying I can let the plumber in on Thursday morning between 9 and 12, and asking him to confirm the time. Under 60 words.”

Try this

Explain a phrase

“My grandson keeps saying something is "mid". What does it mean, and how would I use it in a sentence?”

Try this

Is the pharmacy open

“Search the web and tell me if there's a pharmacy open late tonight near this address, and until what time:”

Try this

In plain words

GPT 5.6 Luna is a chat assistant from OpenAI. OpenAI’s 5.6 line comes in three models, and Luna is the lighter one: made for everyday questions, with quick answers.

It thinks before it answers when a question needs it, reads photos and documents, and can search the web. For most small daily questions, that’s plenty.

How to get the most out of it

  1. Ask short, direct questions. “What can I use instead of buttermilk?” gets a quick, useful answer.
  2. Give it the numbers. Amounts, times and dates make the reply more precise.
  3. Ask it to check the web when the answer may have changed recently.
  4. Move to a fuller model for long letters, documents or plans.

How it compares with its siblings

In the 5.6 line, GPT 5.6 Terra and GPT 5.6 Sol are the fuller models. Other light OpenAI options are GPT 5.4 Mini and GPT 5 mini. For more capability, there’s the newer GPT 6 Astra.

When to pick another model

For writing with a personal touch, try Claude Sonnet 5. For a message in another language, the Translate tool is quicker. Still deciding? Read which model should I use.

Other models worth a look

OpenAI GPT 5.6 Terra

OpenAI

Read the guide

OpenAI GPT 5.6 Sol

OpenAI

Read the guide

OpenAI GPT 5.4 Mini

OpenAI

Read the guide

Frequently asked questions

What's the difference between Luna, Terra and Sol?

They are three models in OpenAI's GPT 5.6 line. Luna is the lighter, quicker one for everyday questions. Terra and Sol are the fuller ones for bigger jobs.

Does it think before it answers?

Yes, on harder questions it takes a moment to think. It's still built for quick replies.

Can it search the web?

Yes. It can look things up online when you need recent information.

Can it read documents and photos?

Yes. It reads PDFs and understands photos.

All of these models, in one place

Chat, images, video and tools with the best AI models. Switch between them whenever you want.

Start for free

Chatmodel is an independent service offering access to third-party AI models. AI can make mistakes. Using Chatmodel means you agree to our Terms and Privacy Policy.