The term "APR" or "Annual Percentage Rate" refers to the annual interest rate being charged on a loan.  All payday loan agreements must set forth the "APR" that you are paying.  This allows you to compare one payday loan to another.  For example, if you have two choices: a payday loan at 600% APR, and a payday loan at 1000% APR, you obviously should choose the loan with the lower fee, if possible.  Because payday loan agreements are usually for short periods (of less than 1 month), the APRs of payday loans are very high.  You can use a payday loan calculator to calculate the APR of a given loan and decide if it is right for you.