Mortgage Calculator
Calculate your monthly payment, total interest, and see the principal vs. interest breakdown.
Monthly Payment
$1,769.79
Loan Principal
$280,000.00
Total Interest
$357,124.57
Total Payment
$637,124.57
How This Mortgage Calculator Works
A mortgage calculator uses four key inputs to determine your monthly payment: home price, down payment percentage, annual interest rate, and loan term. The calculator subtracts your down payment from the home price to get your loan principal, then applies the standard amortization formula.
The amortization formula — Payment = P × [r(1+r)^n] / [(1+r)^n − 1] — accounts for the compounding effect of interest over your loan term. Here, P is the loan principal, r is your monthly interest rate (annual rate ÷ 12), and n is the total number of monthly payments.
Over the life of a typical 30-year mortgage, you'll pay substantially more in total interest than the original loan amount. For example, a $280,000 loan at 6.5% over 30 years results in roughly $357,000 in total interest paid — more than the original principal. This is why even a small rate reduction makes a significant difference.
The pie chart shows how your total payments are split between principal repayment and interest. For most 30-year mortgages at current rates, interest makes up 50–60% of total payments. Choosing a 15-year term or making extra payments can dramatically reduce that interest burden.
Note that this calculator shows your principal and interest (P&I) payment only. Your lender may also collect property taxes and homeowner's insurance through an escrow account, which would increase your actual monthly bill.