Simple Interest Calculator

What is Simple Interest?

Simple interest is a straightforward way of calculating the interest earned or paid on a principal amount of money over a period of time. Unlike compound interest, which involves earning interest on previously earned interest, simple interest is calculated only on the initial amount (principal). This makes it easier to understand and predict how much your investment or loan will grow over time.

How Simple Interest is Calculated

The formula for calculating simple interest is:

Simple Interest = Principal * Rate * Time


  • Principal is the initial amount of money.
  • Rate is the annual interest rate (expressed as a decimal).
  • Time is the period the money is invested or borrowed for, in years.

The Simple Interest Calculator

Our Simple Interest Calculator is designed to help you easily determine the final value of your investment or the total amount owed on a loan when simple interest is applied.


  1. Initial Amount ($): The principal or starting amount of money you are investing or borrowing.
  2. Interest Rate (% per year): The annual interest rate applied to your principal.
  3. Period (years): The length of time, in years, that the money is invested or borrowed.


  1. Final Value ($): The total amount you will have at the end of the period, including both the principal and the interest earned or paid.
  2. Interest ($): The amount of money earned as interest over the period.

How to use the Simple Interest Calculator

  1. Enter the Initial Amount: Input the amount of money you are starting with.
  2. Specify the Interest Rate: Enter the annual interest rate. Make sure to input it as a percentage (e.g., enter 5 for 5%).
  3. Set the Period: Indicate the number of years you plan to invest the money or the duration of the loan.

Once you have entered these values, the calculator will instantly provide you with the Final Value and the Interest earned or paid. This helps you understand the growth of your investment or the total cost of your loan.

Example Calculation

Let's say you have $1,000 to invest at an interest rate of 5% per year for 3 years.

Using the formula:

Simple Interest = $1,000 * 0.05 * 3 = $150

So, the Interest earned would be $150. Adding this to the initial amount:

Final Value = $1,000 + $150 = $1,150

Why use a Simple Interest Calculator?

  1. Ease of Use: Quickly determine the final amount of an investment or the cost of a loan.
  2. Financial Planning: Helps in planning and making informed financial decisions.
  3. Educational Tool: Understand how interest rates and periods affect your finances.

Explore more with our Compound Interest Calculator

For those looking to see how their investments can grow with interest on interest, check out our Compound Interest Calculator. It takes into account the compounding of interest, which can significantly increase your investment returns over time.


Simple interest is a fundamental concept in finance that provides an easy way to calculate the growth of an investment or the cost of a loan. Our Simple Interest Calculator makes this process straightforward and accessible, empowering you to make better financial decisions. Try it out today and see how your money can work for you!

By understanding both simple and compound interest, you can better plan your financial future and make more informed investment decisions.