About BirthdayBump and our sources
A small, free site that turns one date into everything worth knowing about it, calculated exactly wherever something can be calculated exactly.
What's calculated, and how
- Age, days lived, countdowns: calendar arithmetic on your local dates, with leap years; 29 February birthdays observed on 28 February in common years.
- Sun, Moon and rising signs: positions computed with low-precision algorithms from Jean Meeus, Astronomical Algorithms (2nd ed., 1998), in the tropical zodiac.
- Chinese zodiac: your browser's built-in Chinese calendar (ICU), checked against official Lunar New Year dates, with corrections where they differ.
- Life path: the common "reduce month, day, year separately" method, keeping master numbers 11, 22 and 33.
- Generations: Pew Research Center ranges; Gen Alpha/Beta per Mark McCrindle.
- Birthstones: the Jewelers of America / American Gem Trade Association list. Birth flowers: the traditional month flowers.
- Planetary ages: NASA planetary fact sheets.
- Famous birthdays: Wikipedia's "On this day" feed via the Wikimedia API.
What's for fun
Astrology, numerology and the meanings of stones and flowers are cultural traditions. We present them as such, and the AI portrait writer is instructed to do the same.