What is Rule of 72 Calculator?

A tool using the Rule of 72 to estimate how long it takes for an investment to double. Also calculates the required interest rate to double within a target period. Useful for quick financial planning.

How to Use

1. Select the calculation mode (years to double / rate needed).
2. Enter the annual interest rate or target period.
3. Click 'Calculate'.
4. Compare the Rule of 72 approximation with the precise calculation.

Key Features

• Time-to-double calculation
• Required rate reverse calculation
• Rule of 72 approximation vs. precise calculation comparison
• Intuitive result display

Tips

• Rule of 72: 72 ÷ interest rate (%) = years to double (approximation).
• At 8% annual return, your investment doubles in about 9 years (72÷8).
• This rule is a compound interest approximation — accuracy decreases at higher rates.