Overview
What this tool does
An age calculator turns a date of birth into your exact age right now: not just years, but calendar-accurate years, months, and days, plus totals in months, weeks, days, hours, minutes, and seconds. It also tells you when your next birthday is, what day of the week it falls on, and exactly how long until it arrives. Useful for filling out forms with an exact age, settling a "how old am I in days" debate, scheduling around milestone birthdays (turning 21, 30, 65), or planning anniversaries. The live mode updates every second so you can watch your age tick. Runs entirely in your browser, no upload, no signup. You can also calculate age at a specific past or future date by switching off live mode.
How to
Use it in 3 steps
- Pick your date of birth in the first field.
- Leave 'Live (right now)' checked to see your age update second-by-second, or uncheck it and pick any other date to find your age on that day.
- Read the big number (years / months / days) and the totals grid below.
- The Next Birthday card shows the upcoming date, the day of the week, and the exact time remaining.
FAQ
Frequently asked questions
▶How is 'months' counted when months have different lengths?
Calendar-accurate: month N to month N+1 counts as one month regardless of length. For example, Jan 31 + 1 month = Feb 28 (or 29 in a leap year), then +1 day reaches Mar 1. This matches how birthdays work in everyday speech.
▶What happens for a Feb 29 birthday in a non-leap year?
We follow the Microsoft and iOS convention: the celebration date in a non-leap year is Mar 1. So someone born Feb 29, 2000 has their 26th birthday on Mar 1, 2026 (not Feb 28).
▶Why does my 'total seconds' tick exactly when 'years' doesn't change?
Year/month/day are calendar units that only change on date boundaries. The totals are continuous time differences that change every second, which is why the totals grid feels alive even when the headline doesn't change.
▶Is any data sent to a server?
No. Date math is pure JavaScript that runs in your browser. The date you enter never leaves your device.
▶Can I calculate age at a past or future date?
Yes. Uncheck 'Live' and pick any date in the 'Age at date' field. Useful for things like 'how old will I be on January 1, 2030' or 'how old was my grandmother on the day she got married.'
▶Why doesn't this handle time zones?
Dates of birth are conventionally treated as date-only (no time-of-day, no time zone) so this tool follows the same convention. If you need second-precision across time zones, use a date-time tool instead.