Remember to use negative values for owed balances and money paid to the account, positive values for balances in your favor and money withdrawn from the account.
Also, enter the interest rate per period, not per year. If you are making monthly payments and have an annual interest rate, divide the annual rate by 12 (and see my note at the bottom of this page). Thus, an 8% annual rate would be entered as 8/12 or .666667... (either form is accepted). All fields must be filled in, use zeros if necessary.

The variables used are:

• pv (present value) = The starting balance in an account. This number can be zero, positive, or negative (as when you have taken a loan).
• fv (future value) = The ending balance after a certain number of payment periods (np).
• np (number of periods) = The number of payment periods, usually expressed in months.
• pmt (payment) = The amount of each periodic payment
• ir (interest rate) = The interest rate on the account per period.