Glossary term
Crude birth rate (CBR)
The number of live births per 1,000 people in a population per year. It is called "crude" because the denominator is the total population rather than only women of reproductive age — making it sensitive to age structure. A young population generates a higher CBR than an ageing one, even if each woman is having the same number of children.
CBR = (Live births in year ÷ Mid-year population) × 1,000 Why "crude" — and why it matters
The crude birth rate is "crude" in the statistical sense: the denominator includes everyone — men, children, and the elderly — not just women of childbearing age. This means the same underlying fertility behaviour (say, women averaging 2.5 children each) produces different CBRs in different countries, depending on how many women of reproductive age there are in the total population.
A country with a young age structure — like Niger or Mali — has many women in their 20s and 30s relative to total population, producing a high CBR even if individual women are having only moderately more children than average. A country with an old age structure — like Japan or Germany — has far fewer women of childbearing age relative to population, producing a low CBR even before you account for low TFR.
This is why the UN WPP and most demographers prefer TFR for comparing fertility behaviour across countries. CBR remains useful for historical tracking and computing natural increase — it is one of the easiest quantities to calculate from a census and vital statistics system.
How global CBR has changed since 1960
The global crude birth rate peaked at around 37 per 1,000 in the early 1960s — the height of the post-war baby boom in Western countries combined with persistently high fertility everywhere else. Since then it has fallen steadily as the demographic transition has spread. By 2023 the global average was approximately 17 per 1,000.
The fall is not uniform. Sub-Saharan Africa's CBR remains 35–50 in the highest-fertility countries (World Bank birth rate data). South Korea's fell below 5 per 1,000 in 2023 — effectively halving generational population size every 30 years without immigration. The Our World in Data birth rate series provides country-level charts going back to 1950.
CBR and population momentum
One of the most important uses of CBR is illustrating population momentum. When a country has a large cohort of young adults — the legacy of high fertility a generation earlier — it will produce many births even if individual fertility has fallen. India through the 1990s and 2000s is the textbook case: TFR was falling steadily toward replacement level, but the absolute number of births, and hence the CBR, remained elevated because the large cohort born during the high-fertility 1970s was at peak childbearing age.
This momentum effect means population keeps growing for decades after TFR falls to replacement level — because the large cohort has not yet aged out of childbearing. It is why global population has continued to grow even as the world TFR approaches 2.1. Read more about this dynamic in our article on how the world reached 8 billion and our analysis of sub-Saharan Africa's growth engine.
Frequently asked questions
What is the crude birth rate?
The crude birth rate (CBR) is the number of live births per 1,000 people in a population during a given year. It is called "crude" because the denominator is the total population rather than only women of reproductive age, making it sensitive to the population's age structure.
What is the global crude birth rate today?
The global crude birth rate was approximately 17 per 1,000 in the early 2020s, down from a peak of about 37 per 1,000 in the 1960s. Sub-Saharan Africa has CBRs of 35–50 in the highest-fertility countries (World Bank data); Japan and South Korea are below 7 per 1,000.
How does CBR differ from TFR?
The total fertility rate (TFR) measures the average number of children a woman would have over her lifetime at current age-specific birth rates. It removes the effect of age structure, making it a purer measure of childbearing behaviour. CBR is simpler to calculate but conflates fertility behaviour with age structure effects.
Why can a country have a high CBR but a falling TFR?
This is population momentum. A country with a large cohort of young adults (the result of high fertility a generation earlier) will produce many births even if each woman is having fewer children. India in the 1990s is a classic example: TFR was falling steadily, but the CBR remained relatively high because the baby boom cohort of the 1970s was at peak childbearing age.