^ $15 on $100 over 14 days is ratio of 15/100 = 0.15, so this is a 14-day rate. Over a year (365.25 days) this 14-day rate can aggregate to either 391% (assuming you carry the $100 loan for a year, and pay $15 every 14 days: 0.15 x (365.25/14) = 3.91, which converts to a percentage increase (interest rate) of: 3.91 x 100 = 391%) or 3733% (assuming you take out a new loan every 14 days that will cover your principal and "charge", and every new loan is taken at same 15% "charge" of the amount borrowed: (1 + 0.15)365.25/14 − 1 = 37.33, which converts to a percentage increase (interest rate) of: 37.33 x 100 = 3733%).
However, despite the tendency to characterize payday loan default rates as high, several researchers have noted that this is an artifact of the normal short term of the payday product, and that during the term of loans with longer periods there are frequently points where the borrower is in default and then becomes current again. Actual charge offs are no more frequent than with traditional forms of credit, as the majority of payday loans are rolled over into new loans repeatedly without any payment applied to the original principal.
Though regulated at the state and federal level, there are still payday lenders that attempt to skirt the rules. Some are online-only lenders based in other countries. Other lenders work around state laws by operating out of Native American reservations. Be wary of brokers that offer to connect you with lending partners – this can result in a lot of calls and emails about offers.