How long does it take to double your money at 10% interest?
At 10% annual interest, compounded annually, it takes about 7.27 years to double your money — close to the Rule of 72 estimate of 7.2 years.
How is this calculated?
This uses the compound interest formula solved for time: years = ln(multiple) / (n × ln(1 + rate/n)), where n is the compounding frequency. At 12% annual compounding, for example, money roughly doubles in about 6 years, following the well-known "Rule of 72" approximation (72 ÷ rate).