📈 Compound Interest Calculator

See exactly how your money grows over time with interactive charts and year-by-year breakdowns.

Interactive growth chart Monthly contributions Year-by-year breakdown
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The Power of Compound Interest

Albert Einstein reportedly called compound interest the "eighth wonder of the world." When you earn interest on your interest, small amounts of money can grow into extraordinary wealth over time.

The Rule of 72

A quick way to estimate how long it takes to double your money: divide 72 by your annual interest rate. At 8% annual return, your money doubles every 9 years (72 ÷ 8 = 9).

Why Start Early?

Someone who invests $500/month starting at age 25 will have significantly more at retirement than someone who starts at 35 with the same monthly contribution — even though they invest for 10 fewer years. Time is the most powerful variable in compound growth.

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