This calculator finds the missing variable for a loan. If you know the payment, term and the loan amount it calculates the interest rate. If you know the payment amount, loan amount and the interest rate, it calculates the term. Get the idea? Want a free version that runs standalone on your Windows PC? I recently updated mine!. (Right click and select "Save Link As" or "Save Target As" to save file to your computer) It is a 232KB Win32 executable that should run on any W98/NT/2000/XP system built in the last 15 years.