Simple Interest Calculator

Initial Investment

Interest Rate


Length of Time




Simple interest is a method to calculate the amount of interest charged on a sum at a given rate and for a given period of time. In simple interest, the principal amount is always the same, unlike compound interest where we add the interest of previous years principal to calculate the interest of the next year.

Simple Interest Equation

I = PTR/100

  P = Principal Amount
  I = Interest Amount
  r = Rate of Interest per year in decimal; r = R/100
  R = Rate of Interest per year as a percent; R = r * 100
  t = Time Period involved in months or years