ChatGPT Custom Instructions: Examples by Business Type

If you find yourself starting every ChatGPT conversation with the same paragraph about who you are, what you do and how you like things written, custom instructions will save you a lot of typing. Write it once, and ChatGPT considers it in every chat.

Below you'll find how to set them up, what to put in them, and ready-to-paste examples for eight different kinds of small business. Swap the brackets for your own details and you're done.

What are ChatGPT custom instructions?

OpenAI describes custom instructions as a way to share anything you'd like ChatGPT to consider in its responses. They apply immediately to all your chats, including existing conversations, and they're available on every plan on the web, desktop, iOS and Android.

You can edit or delete them at any time, and they aren't shown to people who view a chat you've shared by link.

How do you set up custom instructions in ChatGPT?

On the web or desktop app:

1. Open Settings and select Personalization.
2. Make sure Enable customization is switched on.
3. Type your instructions into the Custom Instructions field.

On iOS or Android, open Settings, select Customize ChatGPT, make sure Enable customization is on, and add your instructions. To stop using them, switch Enable customization off, and delete the text if you want it gone for good.

How long can custom instructions be?

OpenAI says Free and Go users can save up to 1,500 characters, and Plus, Pro, Enterprise, Business and Education users can save up to 5,000 characters. That's plenty for a sharp set of instructions. If you're running out of space, you're probably describing rather than directing, and the examples below will help you tighten it.

What should you put in custom instructions?

The instructions that work best answer four questions:

• Who are you? Your business, who you serve and your role.
• How should it write? Tone, UK or US English, words you never use, length.
• How should it behave? Ask before assuming, give one option first, say when it's unsure.
• What do you use it for most? So it leans towards the right kind of help.

Here's a general template that covers all four.

Copy this prompt

I run [business name], a [type of business] serving [who you serve] in [area or online].
Write in [UK / US] English, in a [plain / warm / direct] tone, with short sentences and no jargon.
Never use these words: [list].
I mostly use you for [emails / social posts / planning / customer replies].
Ask me a question if anything important is missing, rather than guessing.
Give me one strong option first, and offer alternatives only if I ask.

Custom instructions examples for small businesses

Pick the one closest to your business and adapt it.

For a bakery or cafe

Copy this prompt for a bakery

I run a small independent bakery. My customers are local families and office workers.
Write warmly and simply, like a friendly chat over the counter. Mention ingredients and seasonality where it fits.
Never make health claims about our food. Keep social posts short and end with a clear reason to visit.

For a salon or beauty business

Copy this prompt for a salon

I own a hair and beauty salon. Clients book for regular appointments and special occasions.
Write in a friendly, confident tone. Keep messages short enough to read on a phone.
Always include a clear way to book, and never promise results we can't guarantee.

For a coach or consultant

Copy this prompt for a coach

I'm a business coach working one to one with owners of small service businesses.
Write like a straight-talking mentor: practical, encouraging, no hype.
When I ask for content, start from a real problem my clients face, and end with one action they can take today.

For a trades business

Copy this prompt for a trades business

I run a [plumbing / electrical / building] business serving homeowners in [area].
Write plainly, as if explaining to a customer on their doorstep. No technical jargon unless I ask.
For quotes and follow-ups, be clear about what's included and what happens next.

For an online shop

Copy this prompt for an online shop

I sell [products] online to [customers].
Write product descriptions that lead with the benefit, then the details. Keep them scannable.
Use our brand voice: [describe it]. Never invent product features. Ask me if a detail is missing.

For a bookkeeper or accountant

Copy this prompt for a bookkeeper

I run a small bookkeeping practice for sole traders and small limited companies.
Write clearly and calmly. Explain any technical term in plain English the first time it appears.
Never give tax advice as fact; suggest what to check and with whom. Never ask me to paste client account details.

For an estate or letting agent

Copy this prompt for an estate agent

I'm an independent estate and letting agent in [area].
Write property descriptions that are accurate and specific: describe what's there, not what might be. No cliches such as 'deceptively spacious'.
For emails to landlords and tenants, be polite, clear and brief, with the next step in the first two lines.

For a personal trainer or fitness studio

Copy this prompt for a personal trainer

I'm a personal trainer running small group and one-to-one sessions.
Write in an upbeat, encouraging voice, but never shame anyone or promise specific results.
Keep posts short, give one practical tip each time, and suggest checking with a GP before starting anything new where it matters.

For more ready-made prompts by business type, my ChatGPT prompts for bakery owners show the same approach applied to everyday jobs.

How do custom instructions work with temporary chats?

OpenAI says that before a temporary chat begins, you choose whether it's personalised. A personalised temporary chat can use your custom instructions and memories; an unpersonalised one doesn't. That's handy when you want a clean answer without your usual preferences shaping it.

Are custom instructions used to train ChatGPT?

OpenAI says information from your use of custom instructions may be used to improve model performance, and points to its data controls if you want to opt out. To do that, go to Settings, Data controls and turn off Improve the model for everyone. Custom instructions are included if you export your ChatGPT data, and they're deleted if you delete your account.

Why aren't my custom instructions working?

• Check Enable customization is on. It's easy to switch off by accident.
• Be specific. 'Be professional' is vague. 'Short sentences, no exclamation marks, sign off as Sam' is clear.
• Remove contradictions. Asking for 'detailed but brief' answers pulls in two directions.
• Use examples. A line of your own writing is worth more than three adjectives.

If your drafts still sound like a robot, my prompt to make ChatGPT write like a human is the next thing to try.

Tools that work alongside custom instructions

Custom instructions shape every chat; Projects in ChatGPT go a step further by keeping files and context for one job together, and custom GPTs let you build a dedicated assistant for a single task you can share with your team. Keep a master copy of your instructions in a Google Doc or Notion page so you can reuse them in Claude or Gemini too.

If you'd like instructions written and tested for your whole team, this is how I work with business owners.

If you want the full set, start at the ChatGPT Prompts and Limits: 30 Guides to Fun Prompts, Photo Edits and Daily Caps.

Frequently asked questions

Where do I find custom instructions in ChatGPT?

On the web or desktop, go to Settings, then Personalization, make sure Enable customization is on and use the Custom Instructions field. On iOS and Android, go to Settings, then Customize ChatGPT.

How many characters can ChatGPT custom instructions have?

OpenAI says Free and Go users can save up to 1,500 characters, and Plus, Pro, Enterprise, Business and Education users up to 5,000 characters.

Do custom instructions apply to old chats?

Yes. OpenAI says updates to custom instructions are applied immediately across all chats, including existing conversations.

Are custom instructions available on the free plan?

Yes. OpenAI says custom instructions are available on all plans on web, desktop, iOS and Android.

Can I turn custom instructions off?

Yes. Switch Enable customization off in Personalization, or Customize ChatGPT on mobile, and delete the text if you want it removed.