See the power of compound interest — watch your investment grow year by year with a beautiful interactive chart.
Compound interest is calculated on both the initial principal and the accumulated interest from previous periods — meaning you earn interest on your interest, causing exponential growth.
The Rule of 72: divide 72 by the annual rate to estimate years to double. At 7%, money doubles roughly every 10.3 years.
On the chart, the gap between the green "Total Value" line and the gold "Total Invested" line is the interest you earned — that gap is the magic of compounding growing wider each year.