ChatGPT custom instructions: how to set them up (with examples)
How to turn on ChatGPT custom instructions on web and mobile, character limits by plan, what to write and what never to include. With ready-to-copy examples.
Custom instructions are text ChatGPT takes into account in all your conversations, so you don’t have to repeat “keep it short” or “no jargon”. They’re available on all plans, on web, desktop, iOS and Android.
How to turn them on
Web and desktop: Settings > Personalization, make sure Enable customization is on, and type in Custom Instructions.
iOS and Android: Settings > Customize ChatGPT, turn on Enable customization, and type your instructions.
To turn them off, switch the same toggle off and optionally delete the text.
What to write (and what not)
Works well: language and tone, format (“answer first, then explain”), general context (“I work in customer service”), honesty (“if you don’t know, say so”).
Never include ID numbers, addresses, health data, passwords or client data. See data you shouldn’t paste into AI.
Limits by plan
OpenAI states a maximum of 1,500 characters on Free and Go and 5,000 on Plus, Pro, Business, Enterprise and Education.
Privacy
OpenAI notes that information from custom instructions is also used to improve models unless you turn off Improve the model for everyone in Settings > Data controls. Instructions are included in your data export and deleted within 30 days if you delete your account. More in ChatGPT privacy.
On Gemini, the equivalent for specific tasks is Gems.
In the glossary: System instructions.
In the glossary: Custom GPT.
Frequently asked questions
How many characters can I write?
According to OpenAI, up to 1,500 characters on Free and Go, and up to 5,000 on Plus, Pro, Business, Enterprise and Education.
Do they apply to old chats?
OpenAI says changes apply immediately across all chats, including existing ones; previous versions remain visible in those chats’ history.
Can people opening a shared link see them?
No. OpenAI says your instructions aren’t shared with shared-link viewers.
Keep reading
Sources
- ChatGPT Custom Instructions — OpenAI
- Data controls in ChatGPT — OpenAI
Change log
- : First published with OpenAI’s official help as checked that day.
Educational content, prepared with the help of AI tools, with sources cited. It is not a substitute for professional advice. Tools change fast: if you spot something out of date, write to us at contacto@cognenza.com. How we work.