1. Money
Compound Interest Calculator
Calculate Interest Earnings

This compound interest calculator tells you how how much you'll have saved in your account after any period of time that you choose. You'll know how much of your final balance is due to interest earnings (on top of your initial deposit), and you can use the calculator to see how different interest rates affect your final account balance.

Instructions for using the compound interest calculator:

  • Put your original deposit amount into the box for "Principal"
  • Enter your interest rate (APY) in the "Rate" box
  • Enter a time period into the "Years" box
  • Finally, click Calculate to see what your final account balance will be (the interest you earned will be broken out separately as well)

Note that the compound interest calculator allows you to enter your time period in full years or partial years. For example, if you want to calculate interest for 6 months, enter ".5" in the Years box (or enter 1.5 for a period of 18 months).


Example: Assume you deposit $1,000, which will earn 5% over the next two years. How much money will you have? Use the compound interest calculator to find out.

To calculate the answer, enter "1000" (for your $1,000 deposit) in the box labeled "Principal." Next, enter "5" (for the 5% interest rate) in the box labeled "Rate." Finally, enter "2" (for the two year time frame) in the box labeled "Years." Click submit, and you should see that you'll have $1,102.50. The box labeled "Amount" will show "1102.5" (your final account balance). The box labeled "Interest" will show "102.5" (the amount of interest you earned).

Be sure to experiment with different interest rates and time periods to see how powerful compound interest can really be.

Behind the Numbers

Using a calculator is the fastest and easiest find out how much you'll have, but you might also want to understand what the compound interest calculator is doing - where do the numbers come from? Read more about earning and calculating interest so that you understand the basic concepts behind the activity you see in your bank account. Knowing how interest works can help you make better informed decisions.

If you found the compound interest calculator handy, see our other calculators.

You can opt-out at any time. Please refer to our privacy policy for contact information.

©2014 About.com. All rights reserved.