Interest Calculator

Interest Calculator

Annual Interest Rate (%):
Interest Type:
Compounding Periods per Year:
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Interest Definition

This application calculates the interest earned on an investment or owed on a loan given the following inputs:

  • Principal: The initial amount of money invested or loaned.
  • Annual Interest Rate (%)
  • Interest Type: Simple, Compound, or Continuous
  • Years: Time in which the money will be invested or borrowed.
  • Compounding Periods per Year: Specified in the terms of the agreement.

This calculator will be useful for anyone trying to compare investment or loan opportunities and weighing risk versus reward for those situations.

Types of Interest

The following types of interest can be calculated by this application:

  • Simple: Simplest form of interest that is earned once per year.
  • Compound: Interest is gained at the end of each compounding period (usually a month) and this interest is included when calculating the interest for the next compounding period.
  • Continuous: Similar to compound interest with an infinite number of compounding periods per year. Calculated using an exponential function.

Given the same annual interest rate and principal, Continuous will always earn more than Compound and Compound will always earn more than Simple.

For example, for a 5 year Certificate of Deposit with an interest rate of 2% and a principal of $5,000, the following interest will be earned:

  • Simple: $300
  • Compound (12 Periods): $315.24
  • Continuous: $315.51

As you can see, the extra amount that you can earn from continuous versus Monthly Compound interest is quite small ($0.27 over 5 years in our example).

Important Comparisons

This application will be most useful for quickly comparing different investment/loan opportunities to determine the highest/lowest possible interest.

For example, pretend you are presented with two investment opportunities:

  • 2.0% Interest Compounded Monthly for 5 Years
  • 2.1% Simple Interest for 5 Years

Which one will provide you with more of an interest return. The simple interest investment has a higher annual interest rate, but because the alternative is compounded monthly it will yield $315.24 in interest, which is slightly greater than the $315 yielded by the Simple interest account.

With this tool, more informed financial decisions can be made and users can be more secure in their understanding of their finances.

How to Calculate Interest

Let's be honest - sometimes the best interest calculator is the one that is easy to use and doesn't require us to even know what the interest formula is in the first place! But if you want to know the exact formula for calculating interest then please check out the "Formula" box above.

Add a Free Interest Calculator Widget to Your Site!

You can get a free online interest calculator for your website and you don't even have to download the interest calculator - you can just copy and paste! The interest calculator exactly as you see it above is 100% free for you to use. If you want to customize the colors, size, and more to better fit your site, then pricing starts at just $29.99 for a one time purchase. Click the "Customize" button above to learn more!