What is the Population Growth Calculator?
Model population growth with exponential and logistic equations. Solve for final population, growth rate r, time, or initial population N₀. Logistic mode includes carrying capacity K, percent of K, and a projection table. Exponential mode shows doubling time. Free, private, and instant in your browser.
How to use the Population Growth Calculator
- Choose exponential or logistic growth.
- Select which variable to solve for (N, r, t, or N₀).
- Enter the known values and pick a time unit.
- For logistic growth, enter carrying capacity K.
- Review projections and copy the summary for ecology homework or lab notes.
Common use cases
- Projecting bacterial culture size after several hours
- Estimating wildlife population growth toward carrying capacity
- Finding growth rate r from two census counts
Frequently asked questions
- What is exponential population growth?
- Exponential growth follows N(t) = N₀e^(rt), where r is the per-capita growth rate. Populations grow without limits when resources are abundant.
- What is logistic population growth?
- Logistic growth adds a carrying capacity K — the maximum sustainable population. Growth slows as N approaches K: N(t) = K / (1 + ((K−N₀)/N₀)e^(−rt)).
- What is doubling time?
- For exponential growth, doubling time is t_d = ln(2)/r in the selected time units. It is the time needed for the population to double.
- What units should I use for r?
- r is per the selected time unit. If time is in years, r is per year (yr⁻¹). Keep N₀, N, r, and t in consistent units.
- Is my data uploaded?
- No. All calculations run locally in your browser.
