ChatGPT custom instructions generator for your business.
Tell ChatGPT who you are once, and it stops writing like a stranger. Answer the questions below and copy the result into your settings. No signup, nothing to install.
About my business I'm the owner of [your business and what it does]. Our customers are [who your customers are]. How to write for us Sound clear and friendly. Write like a real person talking to a customer, with no jargon and no hype words. Use British spelling and pounds (£). Keep answers short. Customer replies should be under 120 words unless I ask for more. Rules If you don't know a fact about my business, such as a price, date or what's included, ask me. Never guess or make one up. If my request is unclear, ask me one question before you start.
Works outside ChatGPT too. Paste the same text into a Claude Project's instructions, or a Gem's instructions in Gemini.
See a finished example
About my business I'm the owner of Hart & Sons, a six-person plumbing and heating firm in Leeds. Our customers are homeowners and landlords who need boilers fitted, serviced or repaired. How to write for us Sound friendly and plain-spoken. Write like a real person talking to a customer, with no jargon and no hype words. Use British spelling and pounds (£). Keep answers short. Customer replies should be under 120 words unless I ask for more. What I mostly use you for Replying to customer emails and messages, writing quotes and proposals, replying to reviews and booking annual boiler services. Rules If you don't know a fact about my business, such as a price, date or what's included, ask me. Never guess or make one up. If my request is unclear, ask me one question before you start. Never promise a start date or a fixed price before we've seen the job. Never offer a discount unless I say so.
This covers the basics. The Business Brain goes further, with an interview prompt that writes the full version for you and 20 business jobs ready to hand over.
Get The Business BrainHow to set it up in two minutes
Fill in your answers
The result updates as you type. Each box shows an example in grey. Write your own business, your customers and the way you talk. The more specific you are, the better the result.
Copy the text
Tap Copy text, or select the box and copy it. It stays under 1,500 characters, so it fits on a free account.
Paste it into ChatGPT
Open Settings, then Personalisation, then Custom instructions. Paste, save, and start a new chat. Every reply from then on knows your business.
Common questions
What are ChatGPT custom instructions?
A short note ChatGPT reads before every chat. Put your business, your customers and how you like things written in there once, and you stop explaining it at the start of every conversation.
Where do I paste them?
In ChatGPT, open Settings, then Personalisation, then Custom instructions. Older guides and some phone apps still call it Customise ChatGPT. Paste the text, save it, and start a new chat.
Is there a character limit?
Yes. Free accounts get 1,500 characters, and paid plans were raised to 5,000 in July 2026. This generator keeps the result under 1,500 so it fits any plan, and the counter turns red if you go over.
Does it work with Claude or Gemini?
Yes. Paste the same text into the instructions box of a Claude Project, or the instructions of a Gem in Gemini. Nothing in it is specific to ChatGPT.
Do you see what I type?
No. The generator runs entirely in your browser. Nothing you type is sent to us or stored anywhere.
Why does it tell ChatGPT to ask instead of guess?
Because the costly mistake is ChatGPT inventing a price, a date or what's included, then putting it in a message to a customer. That rule stops it filling gaps with made-up facts.