Saving & Investing

Compound Interest Explained

Compounding means growth can be calculated not only on the original amount but also on prior accumulated growth.

Simple idea, powerful effect

With compounding, interest or returns added to a balance can themselves participate in future growth. Over long periods, this can create a widening difference compared with growth calculated only on the original principal.

What affects the result?

The starting principal, rate, time, compounding frequency, contributions and withdrawals all influence a projection. For investments, assumed returns are not guaranteed and actual results can vary substantially.

Time matters

Because each period can build on previous periods, additional time can have a large effect on projected growth. This is one reason consistent early saving is often emphasized in long-term planning.

Do not ignore inflation and risk

A nominal future balance does not tell you what that money will buy, and investment returns can be negative. Use compound-growth calculations as scenarios rather than promises.

Try different assumptions with the Compound Interest Calculator.

Examples and calculator projections are educational and do not predict future investment returns.