Humanity Lab
How many people share my birthday?
Choose your calendar birthday to explore how many living people might share it. This is a uniform-calendar scenario, not a measured count for your date.
All ordinary dates return the same result. This is not measured date-specific birthday data.
World · 1 July 2026 · UN WPP 2024 medium projection. Rounded for readability; not a live census.
Your selection stays in this browser. No account, full date of birth, stored selection or server submission is needed.
What does “share my birthday” mean?
People alive at the reference date whose recorded birth month and day match yours, across all birth years. This is different from annual births, babies born today, or people actively celebrating. The Birthday activity is a separate activity model.
How the estimate is calculated
We apply a uniform birth-timing and equal cohort-survival scenario to the existing UN world-population baseline. A Gregorian 400-year cycle has 146,097 days. Each ordinary month/day occurs 400 times, so its weight is 400 ÷ 146,097. Multiplying by 8,300,678,395 gives about 22,726,000 people.
Population ages, survival, registration practices and birth seasonality are not uniform in reality. We do not have a globally representative living-population table by exact birthday. Choosing May 10 rather than November 10 therefore does not create a different, supposedly measured result. No country's seasonal pattern is substituted for the world.
What about February 29?
February 29 occurs 97 times in the same cycle, giving a weight of 97 ÷ 146,097 and about 5,511,000 people in this scenario. It means people born on February 29, not everyone celebrating on that date. It says nothing about whether they celebrate on February 28 or March 1 in other years.
The calculation is a calendar approximation, not an age-weighted reconstruction of actual leap-day birth cohorts. Values are rounded to the nearest thousand to avoid false precision.
Sources and reference date
United Nations, World Population Prospects 2024, World (location 900), Medium variant, 2026. Total and male/female population on 1 July, all ages. Source counts in thousands are converted to people. Percentages use the same dated world total of 8,300,678,395; they do not use the moving homepage counter.
- Original UN demographic indicators workbook — World, 2026, Medium variant
- UN methodology
- UN data licence: CC BY 3.0 IGO