The simple interest calculator has 2 equations. The first simple interest formula used is for calculating payments. It is:
A = payment amount P = principle or amount of loan i = interest rate n = number of time periods
The second simple interest formula is for finding the compounded value of your savings after a given amount of time. It is:
There is only one new variable that is not defined above:
F = future value of money
Knowing the formulas helps you to understand how the values are calculated. However, you will want to use either business calculators or spreadsheets to do the actual calculations.