Rule of 72 Calculator
Fill in the value and the answer updates as you type.
How the Rule of 72 Calculator works
Rule of 72: years to double ≈ 72 ÷ annual rate. The exact value uses ln(2) ÷ ln(1 + rate).
Inputs and results
The Rule of 72 Calculator takes 1 input and gives 2 results.
What you enter
- Annual return (%) — starts at 8.
What you get
- Years to double (rule of 72)
- Exact years to double
Example: Rule of 72 Calculator with the starting values
With annual return 8 %, the calculator returns:
| Years to double (rule of 72) | 9 |
|---|---|
| Exact years to double | 9 |
Change any value above and the results update straight away.
Rule of 72 Calculator FAQ
How do I use the Rule of 72 Calculator?
Enter annual return in the fields, then read years to double (rule of 72) and exact years to double in the result panel. The answer updates as you type, and you can press Calculate or Enter to refresh it. Use “Copy link” to share your exact numbers with someone else.
What does the Rule of 72 Calculator calculate?
Estimate how many years it takes money to double. It returns years to double (rule of 72) and exact years to double from the 1 value you provide.
What values does the Rule of 72 Calculator start with?
It opens with annual return 8 % so you can see a working result straight away. Replace them with your own numbers, or press Reset to return to these starting values.
Is the Rule of 72 Calculator free and private?
Yes. It is free, needs no account, and runs in your browser, so nothing you type is sent to or stored on our servers. See the Privacy Policy for details.
Can I rely on the Rule of 72 Calculator for financial decisions?
Treat the result as a well-rounded estimate. Real situations often have details a general calculator cannot know, so confirm financial decisions with a qualified professional. See the Disclaimer for more.