Estimate your monthly payment, total interest, and payoff timeline
This tool estimates the principal-and-interest (P&I) payment on a fixed-rate home loan. You enter the home price, down payment percent, annual interest rate, and term. The calculator subtracts the down payment to get the loan amount, converts the annual rate to a monthly rate, then applies the standard amortization formula used by most U.S. fixed-rate mortgages.
Monthly payment M for loan amount P, monthly rate r, and number of months n is:
M = P × [r(1 + r)n] / [(1 + r)n − 1]
When the rate is zero, the payment is simply the loan divided by the number of months. Total interest is what you pay over the full term minus the original principal. The yearly table groups each year’s principal and interest so you can see how early payments are interest-heavy and later payments build equity faster.
On a $400,000 home with 20% down, you borrow $320,000. At 7% for 30 years, the estimated P&I payment is about $2,129 per month. Over the full term you would pay roughly $446,000 in interest if you never refinance or prepay—illustrating why rate and term matter as much as purchase price.
Not always. Lenders usually quote P&I plus estimated taxes and insurance. This page focuses on P&I so you can isolate the loan cost. Ask your lender for a Loan Estimate for a full picture.
A larger down payment lowers the loan amount and monthly P&I, and may help you avoid PMI. Keep enough cash for closing costs, moving, and reserves.
Interest is charged on the remaining balance each month. Early balances are large, so early payments are mostly interest. Paying extra principal or choosing a shorter term reduces lifetime interest.
The math is similar for many fixed installment loans, but investment and HELOC products often use different underwriting, rates, and fee structures. Treat this as a starting estimate only.