Estimate how many years it takes to double your investment at a given interest rate.
The Rule of 72 is a quick, handy formula used to estimate the doubling period of an investment:
For example, at an interest rate of 12% per annum, your money will double in approximately 72 / 12 = 6 years. At an interest rate of 8% per annum, it will take 72 / 8 = 9 years to double.
Whether you are evaluating fixed deposit returns, mutual fund compound interest, or stock portfolio projections, understanding the speed of doubling is crucial for long-term planning. The **Rule of 72** is a famous mental math shortcut that simplifies complex compounding calculations. It gives you an instant estimate of when your principal will double. You can check exact compounding details with our Compound Interest Calculator.
By inputting your principal and expected return rate, our online **Rule of 72 calculator** provides doubling timelines and visualizes the principal vs growth segments. You can compare regular monthly plans with our SIP Calculator or plan one-time bulk allocations with our Lumpsum Calculator.
The Rule of 72 is highly accurate for standard return rates between 5% and 20%. For rates outside this range, the approximation drifts slightly. For extremely high interest rates, the Rule of 76 or 78 is sometimes used, but for retail investments (e.g. 8% to 15% return rates), 72 remains the absolute gold standard in corporate finance. Read more about the history of the Rule of 72 on Investopedia.
Visualize your wealth growth with GoQuickTool. Map out monthly goals with our SIP Calculator or calculate one-time deposits using our Lumpsum Calculator.