ToolAtlasHow old is this birth date today, plus the next birthday. It is Gregorian calendar subtraction, not proof of age for a door, a form, or a clinic.
Someone asked how old a birth date is — a party invite, a camp form, a “are they 21 yet” argument that should not go through a cloud age API. That is this page: years, months, days, and the next birthday, in this tab.
It is not a celebrity-age database and not the US legal-age machinery that bars and DMV counters use. If you need the number of weekdays between two arbitrary dates, that is date difference. Clock-in spans belong on hours.
When the number is only a hint
School cutoffs, visa “must be 18 on the travel date,” and insurance issue ages each have their own midnight rule. We subtract calendar dates. We do not apply a statute.
Leap-day births are the usual surprise. Confirm the anniversary your institution prints before you file.
School cutoffs and leap days
US school districts and camp forms often care about age on a cutoff date, not “today.” Change the as-of date. February 29 births are the usual argument: some offices use February 28, others March 1. We do not apply a statute. Visa “must be 18 on the travel date” is the same kind of midnight rule — theirs, not ours.
How to use it
- Enter the birth date and, if you are not asking about today, the as-of date.
- Read years / months / days and the next birthday.
- For a pregnancy timeline, leave this page.
This is calendar math, not an identity service.