Compound Interest Calculator

Enter a starting amount, how much you add each month, a yearly return, and a number of years. The calculator shows the ending value and splits it into the money you put in and the growth from returns, which is compounding at work.

Things to try

• Add ten years without changing anything else. Then go back and double the monthly amount instead, and compare the two.
• Lower the yearly return by one point to see what a 1% yearly fee costs over decades.
• Set the starting amount to zero to see how far regular saving alone goes.

What it leaves out

The ending value is in future dollars, before inflation, taxes, and fees. At 3% inflation, a dollar 30 years from now buys about 41 cents of today's goods. Real returns also arrive unevenly, with losing years along the way, and the order of good and bad years matters once you start withdrawing money.