How compound interest works
Compound interest means returns are earned not only on your original balance, but also on earlier returns. Over long periods, that can create a widening gap between what you contributed and the final balance.
The effect depends mainly on four things: how much you start with, the return you earn, how long the money compounds and how much you add along the way.
Why regular contributions matter
Regular contributions can be just as important as the assumed return. Adding even a modest amount consistently gives compounding more capital to work on over time.
Use the scenarios above to compare more contributions with more time. MaryGee is designed to show the answer quickly, then help you understand what actually changes it.
Frequently asked questions
Is compound interest the same as investment return?
No. Compound interest is a mathematical growth process. Investment returns can rise or fall and are not guaranteed.
Does more frequent compounding increase growth?
With the same nominal annual rate, more frequent compounding can produce a slightly higher effective return.
Should I include regular contributions?
If you plan to keep saving or investing, including them gives a more realistic projection of your total balance.
Is this financial advice?
No. This calculator is an educational tool and does not account for taxes, fees, inflation or investment risk.