Financial institutions like banks often tout their credit products using APR since it seems like borrowers end up paying less in the long run for accounts like loans, mortgages, and credit cards.1
Credit companies and Investment companies generally advertise the APY they pay to attract investors because it seems like they'll earn more on things like certificates of deposit (CDs), individual retirement accounts (IRAs), and savings accounts. Unlike APR, APY does take into account the frequency with which the interest is applied—the effects of intra-year compounding. This seemingly subtle difference can have important implications for investors and borrowers. APY is calculated by adding 1+ the periodic rate as a decimal and multiplying it by the number of times equal to the number of periods that the rate is applied, then subtracting 1
Here's how APY is calculated: