What is compound interest?
Compound interest is interest earned on both your original money and the interest it has already earned. Over time this creates exponential growth. With regular monthly contributions, the effect is even stronger — this calculator compounds monthly and adds your contributions along the way.
Why time matters most
The earlier you start, the more compounding works in your favor. A dollar invested at 25 grows far more than one invested at 45, because it has two extra decades to compound. This is why starting early beats investing larger amounts later.
Project your savings
Model retirement savings, an emergency fund, or any long-term goal. Adjust the rate and time to see the dramatic effect of compounding. Returns are illustrative, not guaranteed — real investments fluctuate. This is not financial advice.