Population reference dates: 1 January, 1 July and calendar years

A population is counted on a date

Populations change every day, so a population number only makes sense with its date. The World Population Prospects 2024 give two standard dates:

• 1 July, the middle of the year. Mid-year figures are used for rates per person, such as births per 1,000 people, and for most of the UN’s summary indicators, including the median age.
• 1 January, the start of the year. Anthrotempo uses the population by single age on 1 January for everything about your age, because it lines up with birth years: on 1 January, every age group is close to one birth cohort.

Counts over a year

Births, deaths and migration are not counted on a date but over a period: the calendar year from 1 January to 31 December. “Births in 2026” means all births during 2026.

The numbers differ

For the world in 2026, the population on 1 January is 8.27 billion, the population on 1 July is 8.3 billion. Both are right: the world gains people during the first half of the year.

How Anthrotempo shows dates

• Every population figure says whether it is for 1 January or 1 July.
• Results for a birthday between two 1 Januaries are interpolated in a straight line, age by age, and labelled as interpolated.
• Census dates and national statistics with other reference dates are not mixed into the UN series.

Last updated 26 October 2026