Mortgage calculator
Estimate your monthly home payment and what it costs over the life of the loan.
Optional monthly costs
Monthly payment
How a mortgage payment is calculated
Your monthly mortgage payment is based on three things: the loan amount (the home price minus your down payment), the interest rate, and the length of the loan. Lenders use an amortization formula that keeps the payment level for the whole term while gradually shifting each payment from mostly interest toward mostly principal.
The formula
Where M is the monthly payment, P is the loan amount, r is the monthly interest rate (annual rate ÷ 12), and n is the number of monthly payments (years × 12).
Worked example
A $400,000 home with $80,000 down leaves a $320,000 loan. At 6.5% over 30 years (360 payments), the principal-and-interest payment is about $2,022.62 a month, and you would pay roughly $408,000 in interest over the life of the loan. Add property tax, home insurance, and any HOA fee to get your full monthly housing cost (often called PITI).
What raises or lowers your payment
- A larger down payment shrinks the loan and the payment.
- A lower interest rate can save tens of thousands over 30 years.
- A shorter term (15 vs 30 years) raises the monthly payment but cuts total interest sharply.
- Extra payments toward principal shorten the loan and reduce interest.
Frequently asked questions
How is a monthly mortgage payment calculated?
The payment is found with a standard amortization formula using the loan amount, the monthly interest rate, and the number of payments. It keeps your principal-and-interest payment the same every month for the whole term.
What does PITI mean?
PITI stands for Principal, Interest, Taxes, and Insurance, the four parts of a typical monthly housing payment. This calculator shows principal and interest, then lets you add yearly property tax, home insurance, and a monthly HOA fee for the full picture.
Does a bigger down payment lower my payment?
Yes. A larger down payment reduces the amount you borrow, which lowers both the monthly payment and the total interest. Putting down 20% or more also usually removes the need for private mortgage insurance (PMI).
Should I get a 15-year or 30-year mortgage?
A 30-year loan has a lower monthly payment but much higher total interest. A 15-year loan costs more each month but is paid off twice as fast and saves a large amount of interest. Try both terms in the calculator to compare.
How much can extra payments save me?
Paying extra toward principal each month shortens the loan and reduces the interest you pay. Even a small recurring extra payment can take years off a 30-year mortgage.