Most founders I work with can describe their product in detail, but when I ask who their ideal customer is, the answer is usually something like "mid-sized B2B companies" or "marketing leaders who want growth." That's true of almost everyone, which means it doesn't help you decide anything.
So I turned the way I build an ICP with clients into a prompt you can paste into ChatGPT, Claude or Gemini. It interviews you about your best customers, asks about 10 simple questions one at a time, and finishes by writing up your ideal customer profile and three buyer personas. The whole thing takes about 10 minutes, and you can download the prompt or copy it from the bottom of this post.
How to use it
- Copy the prompt at the bottom of this post.
- Paste it into a new chat in ChatGPT, Claude or Gemini. If your tool can read websites, it'll start by reading your homepage.
- Answer the questions. Short answers are fine, and if you don't know something, say so and it'll mark it as a gap.
- Read the write-up, fix anything that's wrong, and then check the guesses with a few real customers.
What an ICP is, and why most of them don't help
An ideal customer profile describes the kind of company that gets the most value from what you sell and is the easiest to win. It covers firmographics like industry, size and location, the tools those companies use, and the signals that tell you a company is a good fit right now, like hiring for a certain role or raising a round.
Buyer personas are the people inside those companies. You need both, because a perfect-fit company still won't buy if the person championing you can't explain the decision to the person who signs.
The trouble with most ICP templates is that they're blank boxes, and people fill blank boxes with the customer they hope to have. It works much better when you start with the customers you already have: which ones are happy, getting real value and easy to sell to, what was going on when they started looking, and why they picked you. Once you've told those stories, the patterns are usually obvious, and so are the warning signs in the deals that went badly. That's hard to do with a form and much easier in a conversation, which is why this is an interview.
What the interview asks
It runs in the same order I use with clients, so it starts with real customers, then looks for patterns, and only then gets to the people involved.
- The basics. What you sell, and what a stranger would think you sell after reading your homepage. They're often not the same.
- Your best customers. Three you wish you had more of, what was going on when the best one started looking, what else they considered and why they picked you.
- Patterns and bad fits. The AI drafts the industries, sizes, tools and signals your best customers share, and asks what your worst customers had in common.
- Who's involved. The job titles of the user, the manager and the executive, what worries them, and what the executive needs to see before saying yes.
- The pitch. It drafts the 30-second case your champion would make to their boss, plus your answers to the four positioning questions I ask every client, and you fix whatever's off.
The three buyer personas
Most B2B purchases involve at least three people, and each one needs a different reason to say yes, so the prompt builds one persona for each.
The user is the person who'd use what you sell every day. They feel the problem most and often find you first, but they usually can't sign, so they need help making the case upstairs.
The manager is your champion. They have to explain why you, why now and why it's worth the risk to someone who wasn't on the call, and if they can't, the deal stalls.
The executive is the one who signs. They care about results they can show the board or investors, and they're worried about wasting money on something that doesn't stick.
What you get at the end
- A two or three sentence ICP summary
- Fit filters for industry, size, location and tools
- Buying signals to watch for, and the customers to walk away from
- Three named personas, like "Ops Manager Olivia" or "CEO Sally," with their pains, fears, buying power and what they need to say yes
- The job your customers hire you to do, in one sentence
- Your answers to the four positioning questions and your champion's pitch
- A list of everything it had to guess, with how to check each one
- Five questions to ask real customers, and three things to change first
The prompt
Copy it, or download it as a text file. You can change anything you like.
You are going to interview me to build my company's ideal customer profile (ICP) and three buyer personas. Work the way Mark Evans of Marketing Spark does with his B2B clients: start from real customers, not guesses, and keep the answers specific.
HOW TO RUN IT
- Ask about 10 questions in total. Keep it quick so I don't get bored.
- Ask one question at a time and wait for my answer.
- Keep questions short and plain. If one might be hard, add a quick example of the kind of answer you want.
- Do as much of the work as you can yourself. Whenever you can work something out from what I've said or from my website, draft it and ask me to confirm or fix it, rather than asking me to write it from scratch.
- If an answer is vague ("small businesses", "they want growth"), ask one short follow-up to make it concrete, then move on.
- If I don't know something, say that's normal, note it as a gap, and keep going.
- Never make up facts about my company or customers. Label anything you're guessing as an assumption.
- Be friendly and direct, like a sharp consultant. Show progress as you go, for example "Question 4 of about 10".
THE QUESTIONS
1. What do you sell, and what's your website? (If you can read websites, read the homepage, then tell me in one sentence what a stranger would think we sell and ask if that's right.)
2. Name three customers you wish you had more of, the happy ones who were easy to sell to. What kind of company is each?
3. Think of the best one. What was going on when they started looking, and what else did they consider? (Doing nothing counts.)
4. Why did they pick you in the end?
5. Draft the patterns you see: industries, company size, location, tools they use, and outside signals that suggest a good fit (like hiring for a certain role or recent funding). Ask me to confirm or fix them.
6. Which customers were bad fits, the ones who churned, were painful to serve or took forever to close? What did they have in common?
7. Who's involved in buying? Ask for the job titles of the user (uses it day to day), the manager (champions it internally) and the executive (signs off).
8. What worries the manager and the executive most about choosing wrong?
9. What does the executive need to see before saying yes? (Case studies, an ROI number, a demo, a reference call?)
10. Draft the champion's 30-second pitch to the executive (why this, why now, why it's worth the risk) and our answers to Mark's four positioning questions: what we offer, who we serve, what value we deliver, and how we're different from the alternatives buyers actually consider. Ask me to fix whatever's wrong.
Then ask if there's anything important we missed, and write it up.
THE WRITE-UP
Write a clean document a CEO could skim in five minutes:
1. ICP summary: two or three sentences on the companies to go after and why.
2. Fit filters: a short table of industries, size, location and tools.
3. Buying signals to watch for.
4. Disqualifiers: who to walk away from.
5. Three buyer personas: the user, the manager and the executive, each with an alliterative name and title (like "Ops Manager Olivia" or "CEO Sally"), titles to search for, responsibilities, buying power, pains, fears, dreams, what they need to say yes, and one line on how they'd describe the problem in their own words. Fill in what I didn't say directly from what you've learned, and mark those parts as assumptions.
6. The job to be done, in one sentence: "When ___ happens, they want to ___ so they can ___."
7. Positioning answers to the four questions.
8. The champion's pitch.
9. Gaps and assumptions, with how to check each one.
10. Five questions to ask real customers to confirm or correct this profile.
11. Three next steps to change first on the website, in sales materials or in targeting.
After you deliver it, ask if I want to change anything.
Start now with a one-line welcome, then ask question 1.
What to do with it
Once you have your personas, you can run the buyer panel to see how three buyers like them would react to your website, where they'd get lost and whether they'd book a call.
The most valuable step, though, is the one the write-up ends with, which is to talk to five real customers and check what you guessed. An AI can organize what you already know, but only your customers can tell you why they actually bought. If you'd like help turning your ICP into positioning, a website and a sales story, get in touch.
Questions people ask
What's the difference between an ICP and a buyer persona?
An ICP describes the company, and buyer personas describe the people inside it who use, champion and approve the purchase.
How many buyer personas should a B2B company have?
Start with three: the user, the manager and the executive. That covers most B2B decisions, and you can add more when a role like IT or procurement keeps showing up in your deals.
Which AI tool should I use?
Any chat tool works, including ChatGPT, Claude and Gemini. If yours can read websites, it'll read your homepage first, and otherwise it'll just ask you.
Is this as good as interviewing customers?
No, and the prompt says so. It's a fast way to get what's in your head onto paper and see what you're guessing at, and the customer conversations come after.
How often should I update my ICP?
Look at it every six months, or any time you launch something new, move into a new market or notice good deals stalling.