Identify the loan principal amount
Determine the interest rate
Determine the interest period
Convert the interest rate to a decimal
Use the formula: Interest = Principal × Rate × Time
For monthly interest, divide the annual rate by 12
For daily interest, divide the annual rate by 365
For simple interest, calculate interest only on the original principal
For compound interest, calculate interest on principal plus accumulated interest
Add the interest to the principal to find the total repayment amount
Subtract any payments made to find the remaining balance