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Population Doubling Time Calculator

Time required for a population to double at a constant growth rate.

Compute how long a population (or culture, or investment) takes to double at a constant exponential growth rate using the rule-of-72-style ln(2)/r formula.

Daniel Oh By Daniel Oh
Reviewed by Dr. Helena Ortiz
Published Last reviewed 1 min read

Inputs

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Results

Enter values and click Calculate to see results.
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How to use this calculator

  1. Fill in the inputs above using the units you already have.
  2. Values update automatically as you type — no submit button needed.
  3. Hover any result row for the underlying formula and intermediate values.

Formula

t = ln(2) / r for a constant growth rate r.

In depth

Compute how long a population (or culture, or investment) takes to double at a constant exponential growth rate using the rule-of-72-style ln(2)/r formula.