Compound Interest Calculator
See how your savings or investment grows over time with compound interest.
Result
Final amount
1,647.01
Total interest earned
647.01
How it works
Compound interest means your interest itself earns interest. Each period, the gains are added to the capital, and the next period's interest is calculated on that larger base — which is why growth accelerates over time instead of staying linear. Three levers drive the final amount: the rate, the time, and the compounding frequency. Time is by far the most powerful: money invested early has more periods to snowball, which is why starting young beats investing larger sums later. For a quick mental check, use the rule of 72: divide 72 by the annual rate to estimate how many years it takes to double your money. At 6% per year, that is about 12 years; at 9%, about 8 — without adding a single extra franc, euro or dollar.
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Frequently asked questions
What is compound interest?
It's interest calculated on both your initial capital and the interest already earned, so your money grows faster over time than with simple interest.
How does compounding frequency affect my returns?
The more often interest is compounded (yearly, monthly, daily), the more you earn, because each new interest is added to the base sooner.
What is the rule of 72?
A mental shortcut: divide 72 by your annual return to estimate the years needed to double your money. At 8% a year, that is roughly 9 years.
What is the difference between simple and compound interest?
Simple interest is always calculated on the initial capital only. Compound interest is calculated on capital plus accumulated interest, so it grows faster and the gap widens every year.
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Compound Interest Explained