Rule of 72 Calculator
Estimate how long an investment takes to double, then compare against exact compounding.
Local calculation model
LocalRate and principal stay in this browser session
ShortcutThe Rule of 72 is approximate, especially outside 6-10%
PrivateSave only stores the scenario locally when you choose it
Doubling inputs
Use annual return and initial investment to estimate doubling time.
Doubling time summary
Run calculation to compare shortcut and exact doubling time.
Waiting for calculationCalculate first to review the growth shortcut.