Compound interest calculator

Enter what you have, what you add each month and for how long. We’ll show you what you put in and what you earn in interest.

Budget Pop

This is an estimate with a constant return, before taxes and fees.

What compound interest is

This year’s interest earns its own interest next year. You barely notice at first. Over time, what you earn each year overtakes what you put in.

Why starting early matters

Try going from 20 to 30 years with the same contribution. At 5%, the final amount nearly doubles even though you only contribute 45% more. That’s what time does.

Frequently asked questions

How does it do the math?

It converts the annual return into a monthly one and adds each contribution at the end of the month.

What return is realistic?

It depends on where you invest and how much risk you take. A savings account pays far less than the stock market, and the stock market doesn’t return the same each year. Try several percentages.