How many years to double your money at 8% monthly compounding?
Based on these numbers, it takes about 8.69 years to reach that multiple.
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).