Interest on your account is calculated daily. You can calculate your interest using this formula:

Your principal balance x Your annual percentage rate ÷ 365 (days in a year) = Daily interest charge For example, you owe $12,000. Your annual percentage rate is 22%. So, using the formula above: $12,000 x .22 ÷ 365 = $7.23 (your daily interest charge, also called per diem)