Biology
Population growth
Project exponential population change from a constant periodic rate.
Calculators / Biology / Population doubling time
Population doubling time calculator
Calculate doubling time from a positive exponential growth rate.
On this page
Doubling time3.8hours
Growth multiplier after 24 hours79.5×
Calculator controls
How to calculate
Calculate doubling time from a positive exponential growth rate.
doubling time = ln(2) ÷ ln(1 + growth rate)
Worked example
Growth rate / hour (%): 20.
Doubling time: 3.8 hours; Growth multiplier after 24 hours: 79.5 ×.
Assumptions and limits
Assumes a constant exponential rate with no lag, resource limit, death, or environmental change.
Results are rounded for display; calculations use unrounded values. Read our calculation methodology.
Understanding the result
Calculate doubling time from a positive exponential growth rate. Every assumption remains visible so the result can be checked or changed.
When this tool is useful
Use the population doubling time for an initial estimate, comparison, or classroom calculation.
Understanding your inputs
| Input | What to enter |
|---|---|
| Growth rate / hour (%) | Enter a number of at least 0.000001 and no more than 10000. |
Frequently asked questions
What are the limits of this population doubling time?
Assumes a constant exponential rate with no lag, resource limit, death, or environmental change.
Can I use different units?
Use the units printed beside each field. Convert measurements first when your source uses different units.