Birth Rate Calculator
Written by Thierno Sadou Diallo, formula verified per our methodology • Last checked on 9/9/2026
The crude birth rate is calculated with (number of births ÷ total population) × 1000, expressed per mille. For 1,500 births in a population of 100,000, the birth rate is 15‰.
Explanation
The crude birth rate is the demographic indicator that complements the mortality rate: it relates the number of births over a given period (usually a year) to the size of the population concerned, expressed per thousand rather than as a percentage, the standard demographic convention. Combined with the mortality rate (see our mortality rate calculator), it lets you calculate a population's natural growth rate — the difference between the two — which shows whether a population is growing or shrinking from births and deaths alone, independent of migration. Like the mortality rate, this rate is called "crude" because it doesn't account for the population's age structure: a population with a high proportion of women of childbearing age will mechanically show a higher birth rate than an aging population, even at identical individual fertility. This indicator is used both in human demography and in animal population ecology, to track a population's dynamics over several successive periods. For population dynamics that already combine births and deaths into a single growth rate, see our population growth rate calculator.
Example: 1,500 births in a population of 100,000
Inputs
Births over the period: 1,500. Total population: 100,000.
Calculation
Birth rate = (1,500 ÷ 100,000) × 1000 = 15‰.
Result
This population's crude birth rate is 15 per mille.
Frequently asked questions
How do you get a population's natural growth rate from this result?
By subtracting the mortality rate from the birth rate, both expressed in the same unit (per mille): a birth rate of 15‰ and a mortality rate of 9‰ give a natural growth rate of 6‰, meaning the population grows naturally by 6 individuals per 1,000 each year, before any effect from migration.
Why does the birth rate vary so much between countries or regions?
Many factors come into play: the population's age structure (a younger population, with more women of childbearing age, tends to have a higher crude birth rate), the level of economic development, access to contraception and education, as well as cultural and political factors specific to each context.
Does this calculation also apply to animal populations?
Yes, the same principle applies in population ecology to track the dynamics of an animal or plant population: the crude birth rate, combined with the mortality rate, lets you assess whether a population is expanding, stable, or declining over a given period.