Age Calculator
Enter a date of birth and get an exact age — down to the minute — plus a countdown to the next birthday.
Result
What this calculator does
Working out an age sounds trivial until you try it. Months have different lengths, leap years shift things by a day, and “two years and eleven months” is not the same as “thirty-five months” for a visa form, a school cut-off or an insurance quote. Getting it wrong on an official document means starting the application again.
This calculator does the calendar arithmetic properly. Give it a date of birth and it returns the exact age in years, months and days, plus the same span expressed as total months, weeks, days, hours and minutes. You can also set a second date to answer “how old was I on the day I started that job?” or “how old will my daughter be when school starts?”
How to use it
- Pick the date of birth. On a phone this opens your device's date wheel; on a desktop you can type the date directly.
- Leave the second field empty to get the age as at today, or set it to work out an age at any past or future date.
- Read the big three numbers — years, months, days — for the answer most forms ask for.
- Scroll down inside the result for the countdown to the next birthday and details such as the day of the week you were born.
The formula
years = end.year − start.year
months = end.month − start.month
days = end.day − start.day
if days < 0: borrow the length of the previous month, months − 1
if months < 0: months + 12, years − 1
Borrowing the real length of the preceding month is what makes this accurate. A simpler “divide the days by 365.25” approach drifts by a day or more and gets leap-year birthdays wrong.
Worked examples
| Scenario | What you enter | Result |
|---|---|---|
| Born 14 March 1990, age today | 1990-03-14 | 35 years, 6 months and a day (as at Sept 2025) |
| Child born 2 September 2019 starting school 1 September 2025 | DOB 2019-09-02, as at 2025-09-01 | 5 years, 11 months, 30 days — one day short of six |
| Someone born on 29 February 2000 | 2000-02-29 | Birthday falls on 28 Feb or 1 Mar in common years |
| Retirement age 60 for someone born 8 July 1968 | DOB 1968-07-08, as at 2028-07-08 | Exactly 60 years, 0 months, 0 days |
Frequently asked questions
The calculator subtracts the date of birth from the target date field by field — year, month, then day. When the day is negative it borrows the true number of days in the preceding month rather than assuming thirty. When the month is then negative it borrows twelve months from the year. This is the same method a registrar or immigration officer uses, so the answer matches official documents.
Yes. Leap days are included in the total-days count automatically because the calculation works from real calendar dates. If you were born on 29 February, the calculator treats your birthday in a common year as falling on 1 March for the countdown, which matches the legal convention in most countries. Your age in whole years still increments correctly every year.
They are two views of the same span. “3 years and 5 months” and “41 total months” describe the same period; the first is how people speak, the second is what forms and eligibility rules often need. Insurance policies, developmental milestones and child-ticket pricing frequently use total months, so both are shown.
Yes — that is what the second date field is for. Set it to a past date to answer “how old was I when I moved here?”, or a future date for “how old will I be at the wedding?” Both dates can be anything the calendar supports, and the second field can sit before or after today.
Because it is measured to the current moment. The years, months and days are calendar quantities that change once a day, but hours and minutes are computed from the real time elapsed since midnight on your birth date. Refresh the page a minute later and the minutes tick up. It is a real number, not a rounding artefact.
No. The calculator works from dates only, so it assumes midnight at the start of the day of birth. For an age in years, months and days this makes no difference at all. It means the hours and minutes figures can be out by up to one day's worth if you want them precise to your actual minute of birth.
Your device's own time zone, because the whole calculation happens in your browser. If you travel across time zones the “today” date follows your device clock. For a birthday countdown this is what you want — your birthday arrives when it arrives where you are standing.
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