Secret Birthdays

You have more birthdays than you think.

Your 1000th week. Your 10,000th day. Your billionth second. One birthday a year was never the whole story - enter your date of birth and see what's hiding in your calendar.

Calculated entirely in your browser. Nothing is stored or sent anywhere. Time of birth averaged as midday.

In good company

Today's secret birthdays

    For your people

    Their secret birthdays

    Add a name and a date of birth; take away a calendar file of their landmark numbers - roughly one every couple of years, so every alert is worth a message. One file per person, each its own removable calendar. Nothing is stored or sent anywhere.

    The rules

    What counts as a secret birthday

    Days
    Every 500th day - your 500th, 1000th, 10,000th and so on.
    Weeks
    Every 100th week. Your 2000th week lands around your 38th year.
    Months
    Every 100th month. The 1000th arrives just past 83.
    Years
    Only the halves. Your 40½ counts; your 40th is just a birthday - you already knew about that one.
    Hours
    Every 10,000th. The 500,000th arrives at 57.
    Minutes
    Every 500,000th. The 10 millionth arrives at 19.
    Seconds
    Nothing until 500 million, around 15.8 years in. Then every 100 million - 600 million, 700 million, and on past your first billion at 31.7 years.
    Collisions
    When two milestones claim the same moment, the better number speaks; ties go to the rarer unit. Calendar doubles - 3000 weeks landing on 21,000 days - both stand. The same news is never told twice.
    Older than
    The almanac also keeps 221 lives that ran their course. You pass each one exactly once, to the day. Names link to Wikipedia.