Rule of 72 Calculator
Estimate how many years to double (or triple/quadruple) an investment at a given return rate.
Years to Double (Rule of 72)10.3 yearsMore precise: 9.9 years
3× (Rule of 114)16.3 yrs
4× (Rule of 144)20.6 yrs
Reference table:
2% / yeardoubles in 36.0 yrs
4% / yeardoubles in 18.0 yrs
6% / yeardoubles in 12.0 yrs
7% / yeardoubles in 10.3 yrs
8% / yeardoubles in 9.0 yrs
10% / yeardoubles in 7.2 yrs
12% / yeardoubles in 6.0 yrs
15% / yeardoubles in 4.8 yrs
20% / yeardoubles in 3.6 yrs
25% / yeardoubles in 2.9 yrs
The Rule of 72 is an approximation. For exact doubling: t = ln(2) / ln(1 + r/100).