Rule of 72 Investment Doubling Tool
Instantly estimate how long it takes your money to double.
Open the Interactive CalculatorHow It's Calculated
Doubling Time (years) ≈ 72 ÷ Annual Interest Rate. Conversely, Required Rate ≈ 72 ÷ Target Years.
Example
Example: at 8% annual return, money doubles in about 9 years (72 ÷ 8). To double in exactly 9 years, you would need an 8% return (72 ÷ 9).
Frequently Asked Questions
How accurate is the Rule of 72?
It is a close approximation for rates between roughly 6–10%; accuracy declines slightly at very high or low rates.
Does this work for debt too?
Yes — it also estimates how quickly compounding interest doubles a debt balance if left unpaid.