Understanding Compound Interest

Compound interest is interest earned not only on your original amount of money, but also on the interest that has already accumulated. Over time, this can allow savings or investments to grow faster than they would with simple interest, which is calculated only on the original principal.

The amount of growth depends on several factors, including your starting balance, interest rate, length of time, how often interest is compounded, and whether you make additional contributions.
 

Why Use a Compound Interest Calculator?

A compound interest calculator can help you see how relatively small changes can affect long-term growth. You can compare different interest rates, time periods, starting amounts, or regular contributions without having to calculate each scenario manually.

It's especially useful for exploring “what if” situations. For example, you can see the difference between saving for 5 years versus 10 years, or compare what happens when you add a monthly contribution instead of relying only on your initial deposit.
 

Simple Example

Suppose you start with $5,000 earning 5% annually and leave the money to grow for 10 years, with interest compounded annually. Without making any additional contributions, the balance would grow to approximately $8,144.

If you also contribute money regularly, the ending balance could be considerably higher. Using the calculator lets you change the contribution amount, interest rate, and time period to see how each factor affects your estimated growth.