Annual Percentage Rate (APR) is a tool that consumers can use as a starting point to compare loan programs. However, it's important to keep in mind that APR is not a perfect system, and not all lenders calculate APR in the same way. While the Federal Truth-in-Lending Act does require any mortgage broker or lender to disclose APR to the consumer, there is no rule written in stone for calculating this number that each and every lender agrees upon.