Glossary term
Mortality rate
A measure of the frequency of death in a defined population over a specified time period — typically expressed per 1,000 or 100,000 people per year. The crude death rate uses total population as denominator; age-standardised rates adjust for age structure to enable fair comparison across populations with different demographic profiles.
CDR = (Total deaths in year ÷ Mid-year population) × 1,000 Types of mortality rate
Demographers and epidemiologists use several distinct mortality measures, each suited to different purposes:
Crude death rate (CDR). Total deaths per 1,000 people per year. Easy to compute but sensitive to age structure. An ageing country shows a higher CDR than a young country even if health conditions are better in the older one. The World Bank CDR database provides country-level time series from 1960.
Age-specific mortality rate. Deaths in a specific age group per 1,000 people in that age group. Removes compositional effects. The Human Mortality Database (HMD) provides age-specific rates for 40+ countries going back to the 19th century.
Age-standardised death rate (ASDR). Applies a standard reference population's age distribution to both countries being compared, eliminating the compositional difference. WHO uses the World Standard Population for global comparisons.
Cause-specific mortality rate. Deaths from a specific cause per 100,000 people per year. WHO Global Health Observatory publishes cause-specific rates for 190+ countries.
Why global CDR has not fallen as fast as you'd expect
One of the most counter-intuitive facts in contemporary demography is that the global crude death rate in 2022 (~7.7 per 1,000) is only slightly below what it was in 1990 (~9 per 1,000) — despite enormous improvements in healthcare, life expectancy, and medicine. The reason is population ageing. As more countries complete the demographic transition, their populations age, and the share of elderly people with inherently higher mortality rates increases. This compositional effect masks real improvements in age-specific mortality.
Japan's crude death rate has risen from around 6 per 1,000 in 1980 to 12 per 1,000 today — not because Japanese health has deteriorated, but because Japan's population is now the world's oldest. Age-standardised Japanese mortality rates have continued to improve throughout. This distinction matters enormously for policy — raw CDR can be deeply misleading as a health indicator for ageing populations.
Mortality and the demographic transition
Mortality decline is the trigger of the demographic transition. Death rates fall first — driven by sanitation improvements, vaccines (particularly against childhood diseases), food security advances, and eventually modern medicine. The infant mortality rate typically leads the decline. Birth rates then follow with a generational lag — creating the "growth gap" that drove 20th-century population explosion.
The role of mortality is also central to understanding the COVID-19 pandemic's demographic impact. The Short-Term Mortality Fluctuations (STMF) dataset from the HMD provided the most timely weekly all-cause mortality data during 2020–2022, enabling researchers to estimate excess mortality when official COVID-19 death counts were incomplete. The pandemic was a major theme at the IUSSP International Population Conference 2021, where excess mortality methodology was debated extensively.
Frequently asked questions
What is a mortality rate?
A mortality rate measures the frequency of death in a defined population over a specified period, expressed per 1,000 or 100,000 people per year. The crude death rate is the simplest form. The Human Mortality Database provides historical age-specific rates for 40+ countries.
What is the global crude death rate today?
Approximately 7.7 per 1,000 in 2022 (UN WPP 2024) — only slightly below the ~9 per 1,000 of 1990, despite major health improvements, because population ageing in many countries increases the share of elderly people with higher intrinsic death rates.
What is the difference between crude and age-standardised mortality?
The crude death rate is sensitive to age structure — an ageing population produces a higher CDR even with better health. Age-standardised rates apply a standard reference population to both countries being compared, eliminating compositional effects and revealing true health differences. The WHO Global Health Observatory publishes standardised rates for 190+ countries.
How does mortality relate to the demographic transition?
Mortality decline is the first stage of the demographic transition — death rates fall before birth rates, creating a growth gap that drove the 20th-century population explosion. Understanding mortality patterns is therefore essential to understanding population growth trajectories.