Answer a buyer's "what will my monthly payment be?" with a one-screen dashboard: have ChatGPT build a payment calculator from your own rate, tax, insurance and HOA numbers, then share it as an estimate: AI agent prompt
Generic online mortgage calculators often skip the county property tax rate, homeowners insurance and HOA dues, so first-time buyers get a number that is too low. On Oct 28, 2026 an X post walked through Matt Spangler's Agent Intelligence #93, which shows buyer's agents how to build a one-screen payment dashboard in ChatGPT in about 20 minutes, on the free plan. The steps: build an interactive calculator with sliders using your lender's current rate and your county's tax rate (telling ChatGPT "Don't look up a rate. Use mine."), expand it into a dashboard with the payment at half a point higher and lower, cash needed at closing and what $25,000 more or less in price does to the payment, add two plain-English sentences on top, then share it as a ChatGPT link or screenshot. Every number is an estimate, not a loan quote, and the client's name and financial details stay out of ChatGPT. The prompt below gives you the same build.
The prompt
Build me an interactive monthly payment calculator I can show a home buyer. Use only the numbers I give you and don't look up a rate: home price [price], down payment [percent], interest rate [rate from my lender], loan length [years], property tax [county rate or yearly amount], homeowners insurance [per year], HOA dues [per month, or 0], mortgage insurance [per month, or 'work it out if down payment is under 20%']. 1) Add sliders for price, down payment, rate and loan length, and show principal and interest, property tax, insurance, HOA and mortgage insurance as separate lines, then the total. 2) Turn it into a one-screen dashboard with: the payment at a rate half a point higher and half a point lower; cash needed at closing with closing costs of about [percent]; and what $25,000 more or less in price does to the monthly payment. 3) Put two sentences at the top, in plain English, that explain what this means for the buyer's search, and move the number a first-time buyer would find most surprising to the top. 4) Label every figure as an estimate, not a loan quote, and add a line telling the buyer to get real numbers from a lender. Put my name and phone number, [name, phone], at the top. I won't include the buyer's name, bank details or other personal financial information.
Fill in the blanks, then copy
This prompt has 9 [bracket]s to fill in. Type your details below and the prompt updates as you go. Your answers stay in this browser and are reused on other prompts with the same blanks. Nothing is sent to us.
Example values are fictional, just to show how a filled-in prompt reads. Replace them with your real details.How to use it
- Copy the prompt above.
- Replace every [bracket] with your own details (use the fill-in-the-blanks box above, which remembers your answers for the next prompt).
- Paste it into ChatGPT and review the answer before you use it.
Works with: ChatGPT
Real-world example: x.com/jbrenizer/status/2115489618519044479
Featured in: Free AI agent prompts for small business (beginner-friendly) · ChatGPT prompts for real estate agents: listing descriptions, leads, showings and closing
Before you use it: what to check
Check yourself
- Check every figure, price and total against your own records before anything is sent, posted or booked. A person approves refunds, discounts, payments and price changes.
- Remove names, contact details, account numbers and other personal data the task doesn't need before you paste, and check your AI tool's data and training settings.
- Read and edit the draft before it reaches a customer or goes public. If you later automate this prompt, start with "draft and notify me", not "send automatically".
- Check names, dates, numbers and any claim against your own source material before you use the answer. AI can misread or invent details.
Using an AI agent? Download this prompt as a SKILL.md agent skill with these checks built in, or get the .zip for Claude.ai. How to install skills.
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