Try it yourself
This is a real, working CalcForms calculator, right here on the page. Enter your details and watch the estimate update on the spot. It is exactly what your customers would use, and every submission reaches you as a lead.
What your customer answers
The live form above asks for these, in this order.
- Their email, so the lead reaches you
- Current loan balance: a number
- Current interest rate %: a number
- Years left on loan: a number
- New interest rate %: a number
What they see: Estimated monthly savings, worked out from their answers on the spot.
What it calculates
- Shows live monthly savings as the homeowner enters current balance, rate, years left and the new rate
- Keeps your real Excel refi worksheet: PMT math on the old and new loans over the same years left
- Captures each homeowner as a warm lead with balance, current rate and projected savings already calculated
- Update the rate inputs or the payment math later just by asking ChatGPT
- Backtest against past refis so the savings you advertise match deals you actually closed
Why it closes more deals
A live number closes deals
Customers who see a real estimate the second they enter their details are far likelier to book than ones told to call for a quote. The number is the hook.
Runs your most complex spreadsheet
Multi-tab workbooks, lookup tables, tiered rates, conditional line items, the lot. If the math runs in Excel, CalcForms runs it behind a clean form.
Update it by chatting
Prices move. Ask ChatGPT to change a rate, add an option, or insert a step and the live form updates in seconds. No developer, no redeploy.
Backtest before you publish
Run your last 20 real jobs through it and tune the formula until the live estimate matches what you actually charge. Ship it once it lines up.
Why calculator forms are worth it, by the numbers
47.3% vs 2.8%
In an analysis of 50,000+ forms, interactive forms averaged a 47.3% conversion rate versus 2.8% for static forms. (Outgrow)
51% of buyers
51% of B2B software buyers now begin their research in an AI chatbot rather than a search engine. (G2, 2026)
1 in 3
A third of B2B buyers have chosen a vendor they had never heard of before, on an AI assistant's recommendation. (G2, 2026)
How this form was built
No template builder and no code. One message to ChatGPT with CalcForms added:
Build this exact form
CalcForms is an app you add to ChatGPT once. After that you build and edit forms just by chatting. Works in Claude too.
- Add CalcForms to ChatGPT. Open the CalcForms app page, click Install plugin, and sign in with your email. One time, about 60 seconds. A free ChatGPT account works. (Using Claude? Setup here.)
- Say the words below. ChatGPT builds the form with your math inside and gives you a link.
- Share it, then change it by asking. Send the link to customers. Change a rate or add a question later just by asking.
Step-by-step: turn your spreadsheet into a form, add your price list, show customers one number. All guides →
"Build a refinance savings calculator from my refi worksheet. Ask for current loan balance, current interest rate, years left on the loan and the new interest rate. Run PMT on the balance at the current rate and again at the new rate over the same years left, and show the difference as estimated monthly savings, rounded to cents."
How does it work? CalcForms is an official ChatGPT app. Once it is added, ChatGPT can build, publish and update real calculator forms for you, all from the chat window. Your customers never need ChatGPT; they just open a link.
What it works out
Current monthly paymentNew monthly paymentSame years leftMonthly savings
Last updated 6 October 2026
FAQ
What does the homeowner actually see?
Does it reset the loan to a new 30-year term?
Can I tweak the assumptions as rates fall?
Build yours in the next 10 minutes.
Free in ChatGPT, unlimited forms and submissions. No credit card.
Add to ChatGPT, free →