Let's say you need to borrow $100 until your next payday. You write the lender a postdated check for the amount of the loan plus the fee. Lenders calculate payday loan fees in one of two ways: as a percentage of the amount you borrow, like 10%, or as a set amount per $1 borrowed, like $15 for every $100 borrowed.
After you write the check, the lender gives you the cash or automatically deposits the loan into your checking account. Then, on your payday, the lender cashes your check unless you extend the loan. Extend the loan, also known as "rolling over" the loan, costs another fee and allows you to keep the loan for another period. You're charged a fee each time you roll over the loan.