Mortgage Calculator

A mortgage payment has two parts: principal (the amount you borrowed) and interest (the cost of borrowing). With a fixed-rate mortgage, your total monthly payment stays the same, but the split between principal and interest changes over time. Early on, most of each payment goes to interest; as the balance shrinks, more goes to principal.

The formula M = P[r(1+r)^n]/[(1+r)^n-1] is the standard amortization formula. It ensures that after n payments, the loan is fully paid off. All calculations run in your browser — no data is sent to any server.

The down payment reduces the amount you need to borrow. A larger down payment means a smaller loan, lower monthly payments, and less total interest. Many buyers aim for 20% down to avoid PMI. Some loans allow as little as 3–5% down, but that increases the loan amount and may require mortgage insurance.

This calculator lets you enter the down payment as either a dollar amount or a percentage. The principal (P) in the formula is: home price minus down payment.

A 15-year loan has higher monthly payments but much less total interest over the life of the loan. A 30-year loan has lower monthly payments but you pay more interest overall. Choose based on your budget and goals. This tool supports 15, 20, and 30-year terms. Shorter terms build equity faster and save on interest.