Rule of 72 Calculator

Understanding the Rule of 72

The Rule of 72 is a simple yet powerful financial formula that helps you estimate how long it will take for an investment to double at a given annual rate of return. It's particularly useful for quick mental calculations and financial planning.

How It Works

Simply divide 72 by the annual rate of return to find the approximate number of years it will take for your investment to double. For example:

• At 6% annual return: 72 ÷ 6 = 12 years to double
• At 8% annual return: 72 ÷ 8 = 9 years to double
• At 12% annual return: 72 ÷ 12 = 6 years to double

Formula Accuracy

The Rule of 72 is most accurate for interest rates between 6% and 10%. For rates outside this range, consider these adjustments:

• For rates above 10%: Add 1 to 72 for every 3 percentage points above 8%
• For rates below 6%: Subtract 1 from 72 for every 3 percentage points below 8%