Rule of 72 Calculator
The Rule of 72 estimates how many years it takes your money to double at a given annual return.
Years to double 9 years
How it's calculated
Divide 72 by the return expressed as a whole number. At 8%, money doubles in about 9 years; at 6%, about 12.
Assumptions
- An approximation: 72 divided by the return percentage. Most accurate for rates near 8%.
Last updated: 2026-08-07
These assumptions follow our general methodology.
Frequently asked questions
How accurate is it?
It is a mental-math shortcut. It is very close for returns between roughly 6% and 10% and drifts a little at the extremes.