US Mortgage Calculator

Start by entering the home price and your down payment in dollars. The calculator subtracts the down payment from the price to find your loan amount, then works out the loan-to-value ratio. A down payment of 20 percent or more avoids private mortgage insurance, so the down payment field has a real impact on your monthly cost.

Next, set your interest rate and loan term. Most US buyers choose a 30-year term, though 15-year loans carry a higher monthly payment with far less total interest. The rate you enter should be the annual percentage rate your lender has quoted. The results update live as you type, so you can try several rates and terms side by side without pressing any button.

Finally, fine-tune the recurring costs. The property tax rate defaults to 1.1 percent of the home value per year, the annual home insurance defaults to 1500 dollars, and the PMI rate defaults to 0.5 percent of the loan per year. Add any monthly HOA dues if your property has them. Replace each default with your own figures, from your county tax bill, an insurance quote and your lender, to get an estimate that matches your situation.

The core of the payment is the principal and interest, computed with the standard fixed-rate amortization formula. The monthly payment equals the loan multiplied by the monthly interest rate, divided by one minus (one plus the monthly rate) raised to the power of minus the number of months. The monthly rate is your annual rate divided by 12, and the number of months is the term in years multiplied by 12. When the interest rate is zero, the formula simply divides the loan evenly across the months.

The calculator then adds the ongoing ownership costs. Monthly property tax is the home price times the annual property tax rate, divided by 12. Monthly insurance is the annual premium divided by 12. HOA dues are added directly as a monthly figure.

PMI is handled conditionally. The calculator checks whether your down payment is less than 20 percent of the home price. If it is, PMI applies and equals the loan amount times the annual PMI rate, divided by 12. If your down payment is 20 percent or more, PMI is zero. The total monthly payment is the sum of principal and interest, property tax, insurance, HOA dues and PMI. The loan-to-value ratio is the loan amount divided by the home price, shown as a percentage.

The large figure at the top is your total monthly payment, the all-in cost of owning the home each month under these inputs. Below it, the monthly breakdown splits that number into its five parts so you can see exactly where the money goes. Principal and interest is usually the largest slice, but property tax and insurance can add several hundred dollars, and PMI can be a meaningful extra cost when your down payment is small.

The loan-to-value ratio next to the loan amount tells you how much of the home you are financing. At 80 percent LTV or below, no PMI is charged. Above 80 percent, the calculator includes PMI and shows a note explaining that it typically drops off as your balance falls toward 78 to 80 percent of the home value. If you see a PMI line you want to remove, increasing your down payment to 20 percent is the direct way to do it.

Treat the result as a careful estimate, not a quote. It assumes a fixed rate and a fully amortizing loan, and it relies on the tax, insurance and PMI figures you enter. Real lender quotes can differ because of escrow timing, points, fees and credit-based PMI rates. Use this breakdown to compare scenarios, then confirm the exact numbers with your lender before you commit.