Investment Doubling Time Calculator: Formula & Worked Example

Estimate doubling time using the Rule of 72. Calculate instantly in your browser with editable inputs, a worked example and clear assumptions. No account required.

How it is calculated

72 ÷ Annual return %

The Rule of 72 is an approximation using a positive constant annual rate.

Worked example

Annual return %

12

Example result: 6.00 years

The interactive tool lets you edit every input and reset to this example. Calculations run in your browser.

Questions and answers

Are my calculator inputs sent to a server?

These calculations run in your browser. The calculator does not send your entered values to a calculation server or save them to your learning account.

Why can the result differ from a full spreadsheet model?

Each calculator uses the equation and assumptions shown on this page. Displayed values may be rounded. A workbook with different timing, fees, filters or source data can produce a different result.

Can I use the calculator without an account?

Yes. All 73 calculators are available to guest learners. The worked example shows the default inputs, and Reset restores them.

Related calculators

• CAGR — Compound annual growth rate between two values.
• Simple Interest — Calculate simple interest.
• Simple Interest Total — Calculate principal plus simple interest.

All 73 calculators · Practise in the Excel Simulator

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