๐ Rule of 72 Calculator
A quick approximation using "72 รท annual rate" โ use a compound interest calculator for an exact figure.
Use the "Rule of 72" (72 รท annual rate (%) โ years to double), a commonly used approximation for compound growth, to estimate how many years it takes an investment to double at a given annual rate โ or, in reverse, the rate needed to double within a target number of years.
How to use
- Choose "From rate" or "From years".
- Enter the annual rate (%), or the target number of years.
- The result is calculated automatically.
FAQ
What is the Rule of 72?
A commonly used financial rule of thumb that approximates the number of years it takes an investment to roughly double under compound growth, using the simple formula "72 รท annual rate (%)".
Why is the number 72 used?
The exact compound-growth formula ln(2)/ln(1+r) is close to 72 for typical interest rates (roughly a few percent to the low teens), and 72 has many convenient divisors, making it easy to calculate by hand.
What if I need an exact compound interest calculation?
The Rule of 72 is only an approximation. For a precise future value, use a compound interest calculator that accounts for the exact principal and time period.