How it works
Monthly payment uses the standard amortizing-loan formula: payment = P × r ÷ (1 − (1 + r)−n), where P is the loan, r is the monthly rate (annual rate ÷ 12), and n is the number of monthly payments. Extra payments go straight to principal, which is why they cut total interest and shorten the loan.
The summary below shows the balance at the end of years 1, 5, 10, 15, 20, 25 and the final year, so you can see the payoff curve without scrolling through every month.
Frequently asked questions
Does this include taxes and insurance?
No — this is principal and interest only. A mortgage payment with taxes, insurance and HOA dues will be higher.
Why do extra payments help so much?
Early in a loan most of each payment is interest. Extra principal early removes interest that would have been charged on it for years.