If you want to pay down a loan ahead of schedule by adding a fixed amount to each payment, this extra payment calculator will show you how much quicker you'll reach loan pay off time and how much money you'll save. Almost every other loan pay off calculator out there uses initial loan amount, rate, date and term of loan. They assume you have not made any additional payments to your principal. If you have, your balance will not match and your answer will not be accurate. This one is smart enough to take that into consideration and use only your current balance, loan rate and payment amount. Accurate data to begin with gives an accurate answer. (Thanks user Jeff for noticing and pointing that out!)
