Interest may be computed as simple interest which is calculated by multiplying the amount of money borrowed by the interest rate and the length of the loan. Simple Interest Formulas and Calculations. For the same length of period a greater periodic yield indicates a better deal all other things being equal.
Multiply the daily interest by the number of days.
To calculate simple interest use this formula. If you need to know the interest for 31 days then enter 31 for the number of days and dont worry about the dates. Simple Interest Formulas and Calculations. Multiply the daily interest by the number of days.