Rule of 72
Rule of 72 Calculator
Estimate how many years it takes money to double at a given rate, or the rate needed to double in a set time, compared with the exact answer.
%
Doubles in (Rule of 72)
10.3 years
Exact answer
10.2 years
Rule of 72 error
0.4%
| Rate | Rule of 72 | Exact |
|---|---|---|
| 2% | 36.0 yrs | 35.0 yrs |
| 3% | 24.0 yrs | 23.4 yrs |
| 4% | 18.0 yrs | 17.7 yrs |
| 5% | 14.4 yrs | 14.2 yrs |
| 6% | 12.0 yrs | 11.9 yrs |
| 8% | 9.0 yrs | 9.0 yrs |
| 10% | 7.2 yrs | 7.3 yrs |
| 12% | 6.0 yrs | 6.1 yrs |
The Rule of 72 is a mental shortcut that is most accurate between about 6% and 10%. It works in reverse for inflation too: at 3% inflation, prices double in roughly 24 years.
