Mortgage Calculator
Estimate your monthly mortgage payment including principal, interest, property tax and home insurance.
About the Mortgage Calculator
A mortgage is the largest financial commitment most Americans ever make, and the monthly payment is what determines whether a home is affordable. The AlarmDaddy Mortgage Calculator gives you a complete PITI estimate — principal, interest, taxes and insurance — so you see the true monthly cost, not just the loan repayment.
Enter the home price, your down payment percentage, the interest rate (APR), and the loan term, then add your local property-tax rate and annual home insurance. The calculator returns the full monthly payment broken into its parts, the total interest you'll pay over the life of the loan, and a principal-versus-interest split. Toggle between 15-, 20-, and 30-year terms to see how a shorter term raises the monthly payment but slashes total interest.
Most US buyers compare a 30-year loan (lower payment, more total interest) against a 15-year loan (higher payment, far less interest). This calculator makes that trade-off concrete in seconds, and pairs naturally with the refinance and affordability questions every buyer asks.
How to use this calculator
- 1Enter the home price.
- 2Set your down payment percentage (20% avoids PMI on conventional loans).
- 3Enter the interest rate (APR) your lender quoted.
- 4Choose the loan term: 15, 20, or 30 years.
- 5Add your local property tax rate and annual home insurance.
- 6Read the full monthly payment and total interest.
The formula
The principal-and-interest portion uses the standard amortizing-loan formula, where P is the loan amount (price minus down payment), r is the monthly rate (APR ÷ 12), and n is the number of monthly payments. Property tax and homeowners insurance are added monthly as escrow to produce the full PITI payment.