CandleChasers

GROWTH & INVESTING

Money Doubling Time / Rule of 72 Calculator

Compare exact compounding time with the Rule of 72 approximation.

Your inputs

Use one currency throughout. Results update as you type.

Your result

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How to use this calculator

Adjust the inputs to your own scenario, then review the result alongside the assumptions below. The $ symbol is a currency label; the tool does not convert exchange rates.

Worked example

At 8%, the Rule of 72 gives 9 years; exact annual compounding gives about 9.01 years.

The formula

Exact years = ln(2) ÷ ln(1 + annual return). Rule of 72 years = 72 ÷ percentage rate.

What the result means

Compare the output with the stated assumptions. Changing an input changes the arithmetic; it does not establish how a real trade or investment will perform.

Assumptions and limitations

Constant positive return and no deposits or withdrawals. The approximation becomes less accurate at extreme rates.

Common questions

What does this calculation include?

Constant positive return and no deposits or withdrawals. The approximation becomes less accurate at extreme rates.

Are the example inputs recommendations?

No. The defaults are worked examples. Enter values appropriate to your own calculation; outputs are estimates rather than forecasts.

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Educational calculations, not a forecast or personalized investment advice. Your inputs are used locally for the calculation and are not submitted by this tool.

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