Rule of 72 Calculator
Quickly determine exactly how long it takes for a compounding investment to double in value using the Rule of 72. Essential tool for forecasting portfolio growth.
Rule of 72 Calculator
Quickly estimate how long it takes for an investment to double at a given rate.
%
%
$
Rule of 72 Calculator
—
—DOUBLING TIME—
EXACT (LOG)—
REAL (ADJ)—
QUADRUPLING—
How to Use Rule of 72 Calculator in 3 Easy Steps
1
Step 1
Input the expected nominal annual return rate for your asset class.
2
Step 2
To project real purchasing power, enter the anticipated macroeconomic inflation rate.
3
Step 3
Observe both the quick heuristic estimation and the deeply precise continuous compounding timeline.
Frequently Asked Questions
The number 69.3 is technically more accurate for continuous compounding (derived directly from the natural log curve). However, 72 is used universally because it is easily divisible by 2, 3, 4, 6, 8, 9, and 12.
Yes! The formula is agnostic. If you carry credit card debt at a horrific 24% APR, 72 ÷ 24 = 3. Your total debt burden will completely double in size every 3 years if left unpaid.
If your investment doubles to $20,000 in ten years, but the cost of bread also doubles over that decade due to inflation, you have gained exactly zero real economic wealth.