Loan Payoff Calculator

A loan payoff calculator answers two questions about a debt you are already carrying. Give it the balance, the annual rate and the monthly payment and it counts the months until the balance reaches zero, with the interest and the size of the final payment. Add an amount you could pay on top each month and it runs the same loan twice, so you can see the months and the interest that the extra payment removes. Interest is worked out monthly and rounded to the cent, as a lender would, and fees or penalties are not modelled.