Sources and method
Every figure on this site is computed from records published by national statistical offices, and every page names the country, the window and the metric it uses.
Publishers by country
- United States: CDC/NCHS and the Social Security Administration, daily counts compiled by FiveThirtyEight (CC BY 4.0) and by Jake VanderPlas; the federal holiday rule from the U.S. Office of Personnel Management.
- England and Wales: Office for National Statistics (Open Government Licence v3.0); the bank-holiday rule from GOV.UK.
- Denmark: Statistics Denmark, births by date and residents by birthday.
- France: INSEE, metropolitan France and the whole country.
- Malaysia: Jabatan Pendaftaran Negara, published by the Department of Statistics Malaysia (CC BY 4.0).
- Canada: Statistics Canada, births by month.
- India: Office of the Registrar General of India, Civil Registration System, and the Department of Economics and Statistics, Government of Kerala.
- Famous birthdays: English Wikipedia, CC BY-SA 4.0.
Method
Each country is one series of recorded births, counted on its own. The U.S. daily file runs CDC/NCHS years 1994–1999 followed by SSA years 2000–2014, two separate stretches with the overlapping years counted once. Dates are compared per occurrence, so February 29 is judged on the leap years it had, and ranks run across all 366 dates. Five countries are compared over one matched window by rank and index. Every row is validated before use, and every page is generated from the records at build time.
How these pages are made
Birthday Traffic is a small independent project. The analysis, wording and code here were produced by the site's author working with AI coding assistance, and every published number is computed by committed code from the named sources. Errors found in the figures are worth reporting; the contact is on Contact.
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