Worked example: $500,000 at 6% over 30 years

Inputs: loan amount $500,000, interest rate 6% per year, term 30 years. The monthly rate is 0.06 ÷ 12 = 0.005, and the number of repayments is 360.

Monthly repayment = 500,000 × 0.005 × (1.005)³⁶⁰ ÷ ((1.005)³⁶⁰ − 1) = $2,997.75 (rounded to cents; unrounded $2,997.7526). Total paid, using the unrounded monthly figure, = $1,079,190.95. Total interest = $1,079,190.95 − $500,000 = $579,190.95. In other words, on a fixed 6% loan with no fees or extra repayments, interest alone exceeds the amount borrowed.

Second check: $300,000 at 5% over 20 years gives a monthly repayment of about $1,979.87, total paid about $475,168.13, and total interest about $175,168.13. Try both examples in the calculator to confirm it returns these figures. If your lender's figure differs, ask whether fees, a different rate, a different term, or rounding explain the gap.