Mortgage Calculator
Estimate your monthly mortgage payment and total interest.
All calculations happen locally in your browser — nothing is uploaded, stored or tracked.
Enter the home price
And your down payment (amount or percentage).
Set the rate and term
Your quoted mortgage rate and loan term.
Add taxes and insurance
Optional annual amounts for a full monthly picture.
What Is a Mortgage Calculator?
A mortgage calculator estimates the monthly payment on a home loan from the purchase price, down payment, interest rate and term. Beyond principal and interest, the real monthly cost of a home includes property taxes, homeowners insurance and often PMI — the calculator includes all of them so the estimate matches reality.
The payment uses the standard amortization formula. The optional property tax, insurance and HOA fields are annual amounts that are converted to a monthly figure and added to the payment.
The Formula
P is the loan amount (price − down payment), r the monthly rate (annual ÷ 12), n the number of payments. Total interest = total payments − loan amount.
Assumptions
Your data never leaves your device.
Every calculation on this site runs in your browser using vanilla JavaScript. Nothing is uploaded, stored or tracked.
- 100% local, client-side calculations
- No data stored on any server
- No tracking, no analytics, no ads scripts
- Works offline once loaded
Frequently Asked Questions
How is a mortgage payment calculated?
Principal and interest use the amortization formula M = P·r/(1−(1+r)^−n); taxes and insurance are added separately as monthly escrow amounts.
What is PITI?
Principal, Interest, Taxes and Insurance — the four components of a full mortgage payment. This calculator shows all four.
How much house can I afford?
Use the mortgage affordability calculator, which works backwards from your income and debts.
Does the calculator include PMI?
It shows PMI when you add it in the optional field — or use the dedicated PMI calculator for the full estimate.
What is a good mortgage rate assumption?
Rates vary constantly; enter the rate you have been quoted or a figure you are comfortable planning with.
Should I include property taxes?
Yes — they are often 0.5–2% of home value per year and materially affect the monthly payment. Enter your local estimate.