Rule of 72 Calculator
Quickly calculate how long it takes to double your investment, or find out what interest rate you need to double it within a specific time frame.
Time to Double your Money:
10.3
Years
Frequently Asked Questions
What is the Rule of 72?
The Rule of 72 is a quick, useful mental math shortcut used in finance to estimate the number of years it takes to double your money at a given annual fixed interest rate. You simply divide 72 by the annual rate of return.
Is the Rule of 72 exact?
No, it is an approximation. However, it is remarkably accurate for interest rates between 6% and 10%, which covers most common investment vehicles like FDs, Bonds, and conservative Mutual Funds.
How do I use it in real life?
If a Bank FD offers 7% per annum, you do 72 ÷ 7 ≈ 10.2. This means it will take roughly 10 years and 2 months for your principal to double. Alternatively, if a friend says 'I doubled my money in 5 years!', you can verify the required growth: 72 ÷ 5 = 14.4% CAGR.