Years for money to double at a rate. The Rule of 72 Calculator takes annual rate of return and returns years to double (rule of 72) plus exact doubling time, years to triple (rule of 114). Results update as you type, and the formula is shown under the result so you can repeat it in your own spreadsheet.
Investment maths is about comparing money at different points in time on a fair basis. Compound rates, discounting and annualised returns let you compare options of different sizes and durations. Use the worked example below to check the maths against your own figures.
How the Rule of 72 Calculator works
A mental shortcut: divide 72 by the annual rate. At 8% money doubles in about 9 years; at 12% in 6. The exact figure is shown alongside.
Worked example
With the example values (annual rate of return of 8%), the years to double (rule of 72) is 9.0 years; exact doubling time 9.0 years, years to triple (rule of 114) 14.2 years. Change any figure above and the result updates immediately; use Copy results to paste the summary into a note or email.
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Frequently Asked Questions
How is years to double (rule of 72) calculated?
years to double ≈ 72 ÷ rate.
Which figures do I need?
Annual rate of return. Take them from the same period and the same set of accounts or reports so the ratio is consistent, and check the example values as a guide to the units expected.
Does the calculator account for taxes and fees?
Only where there is an input for them. For a true net return, add fees and taxes to your inputs or use the stock and crypto profit calculators, which include them.
