How to Calculate Rule of 72
Estimate how long it takes an investment to double using the Rule of 72.
The Formula
yearsToDouble = 72 / annualRateThe rule of 72 formula uses the mathematical relationship: yearsToDouble = 72 / annualRate. Each variable in the formula represents a measurable quantity that affects the final result.
Step-by-Step Method
- 1Identify all input values needed for the rule of 72 calculation.
- 2Substitute your known values into the formula: yearsToDouble = 72 / annualRate.
- 3Perform the arithmetic operations in the correct order (PEMDAS/BODMAS).
- 4Check that your result has the correct units and is within a reasonable range.
- 5Verify using the interactive Rule of 72 Calculator to confirm your answer.
Related Topics
rule of 72doubling timecompound interestinvestment
Use the Interactive Calculator
Skip the manual math — get instant results with our free Rule of 72 calculator.