Age Calculator
Find your exact age in years, months, and days. See your next birthday countdown.
How to Use
- Enter a date of birth using the date picker.
- The "as of" date defaults to today — change it to calculate age at any point in time.
- Age is shown in years/months/days and as total days, weeks, and months.
- Scroll down for the next birthday countdown.
When to Use This
- Filling in a form that asks for exact age in years, months and days rather than just a year of birth.
- Checking an eligibility cut-off, such as a school admission or a scheme's minimum age, by setting the as-of date to the cut-off itself.
- Tracking an unusual milestone, such as a 10,000th day, by reading the total days count and moving the as-of date until it matches.
- Settling an argument about who is older when two birth dates are close together, since the breakdown goes down to the day.
Frequently Asked Questions
About This Calculator
Age in years, months and days cannot come from a single subtraction, because months run from 28 to 31 days. The standard method subtracts the calendar parts separately and borrows: if the day of the month comes out negative, it borrows the length of the month before the as-of date; if months then come out negative, it borrows twelve from the years.
You supply a date of birth, capped at today, and an as-of date that defaults to today. The tool reports the borrowed years, months and days, then total months as years times twelve plus months, total days from the elapsed milliseconds, whole weeks as days divided by seven, and hours as days times 24. The next-birthday countdown appears only while the as-of date is today, and counts forward to the next matching day and month.
Notes & Limits
- For a 29 February birth date the countdown targets 1 March in non-leap years, because the date rolls forward rather than falling back to 28 February.
- Both dates are whole calendar dates with no time of day, so the hours figure is total days multiplied by 24, not elapsed clock hours.
- The countdown row is hidden whenever the as-of date is not today, since a countdown measured from a past or future reference point would mislead.
- Total months is derived from the years and months breakdown, not from dividing days, so it will not match a figure computed as days over 30.