See how your savings grow over time with compound interest. Calculate future value of any investment.
See how your money grows over time
Compound interest is the most powerful force in personal finance — Einstein reportedly called it the 'eighth wonder of the world'. Unlike simple interest which only earns on your principal, compound interest earns on your principal plus all previously earned interest, creating exponential growth over time.
Starting 10 years earlier can more than double your retirement savings. Even small contributions matter enormously over time. The Rule of 72: divide 72 by your interest rate to find how many years it takes to double your money. At 8%, your money doubles every 9 years.
Compound interest rewards time more than almost anything else in personal finance. Someone who invests $300/month starting at age 25 will out-earn someone who invests $600/month starting at age 35 — despite contributing less money overall.
This happens because early contributions have decades to compound, while later contributions only compound for a shorter window. At a 8% average annual return, $300/month from age 25 to 65 grows to roughly $1.05 million. The same $300/month starting at 35 only reaches about $440,000 — less than half, despite only missing 10 years.
The lesson isn't "it's too late to start" — it's that every year you wait costs you disproportionately more than the year before. If you're starting later, the math says to increase your contribution rate to compensate, not to give up.
Use the calculator above to model your own numbers. Try sliding the "years to grow" field down by 5 or 10 years and watch how dramatically the future value drops — it's the clearest way to see why financial advisors hammer on starting now, even with small amounts.