How to calculate your exact age
- Enter your Date of birth with the date picker or by typing it.
- Leave Age at this date on today, or pick another date to see how old you were (or will be) on that day. The Today button puts it back to the current date.
- Read your exact age in years, months and days in the coloured box, with totals, the weekday you were born and a countdown to your next birthday below it.
- Use Copy result to paste the summary into a form or message. Tick Remember my date of birth on this device if you want the date filled in next time.
How the age calculation works
Age is counted the way people count it on official forms: completed years, then completed months since your last birthday, then the days left over. The calculator works on calendar dates, not average month or year lengths, so it is exact for any pair of dates.
- Years and months. The calculator finds the last date on which you completed a whole number of months. Your birthday each year is the completed year; the same day number in each month is a completed month.
- Days. The remaining days are counted from that last monthly anniversary to the chosen date, using the real length of the month in between (28, 29, 30 or 31 days). For example, from 15 January to 10 March is 1 month and 23 days, because February 2025 has 28 days.
- Month-end births. If you were born on the 29th, 30th or 31st and a month is shorter, your monthly anniversary in that month falls on its last day. Someone born on 31 January has completed one month on 28 February (or 29 February in a leap year), and is 1 month and 1 day old on 1 March.
- Totals. Total days is the number of calendar days between the two dates. Weeks are total days divided by 7, with the remainder shown as days. Hours are total days multiplied by 24, which is why they are marked as approximate: they ignore the time of birth and clock changes.
Birthdays on 29 February
If you were born on a leap day, your birthday only appears on the calendar every four years or so (century years such as 1900 and 2100 are not leap years, but 2000 was). This calculator treats 28 February as your birthday in non-leap years, so you complete another year on 28 February and the countdown points there. Legal rules differ by country: some treat 1 March as the day a leap-day baby turns a year older for official purposes. If the exact day matters for a legal age, check your local rules.
Examples
| Date of birth | Age at this date | Exact age | Total days |
|---|---|---|---|
| 15 Jan 2000 | 10 Mar 2025 | 25 years, 1 month, 23 days | 9,186 |
| 31 Jan 2023 | 1 Mar 2023 | 0 years, 1 month, 1 day | 29 |
| 29 Feb 2000 | 28 Feb 2023 | 23 years, 0 months, 0 days (birthday) | 8,400 |
| 1 Jan 1990 | 1 Jan 2026 | 36 years, 0 months, 0 days | 13,149 |
Typical uses: checking an age limit or eligibility date, filling in forms that ask for age in years and months, working out a child's age in months or weeks, counting the days to a birthday, or measuring the time between two events such as a start date and today.
Privacy: the calculation runs entirely in your browser. Your date of birth is not sent to a server. It is only stored on your own device if you tick the remember box, and unticking it deletes it.
More quick helpers: work out discounts and changes with the percentage calculator, count down to an event with the online timer, or browse all everyday tools.
Frequently asked questions
How do I calculate my age from my date of birth?
Subtract your birth year from the current year, then take one year off if your birthday has not happened yet this year. For months and days, count the whole months since your last birthday and then the days since the last monthly anniversary. The calculator above does all of this for you, including different month lengths and leap years.
How old am I in days?
Enter your date of birth and read the Total days box. It counts every calendar day from your birth date up to the chosen date, with leap days included. Someone born on 1 January 1990 is 13,149 days old on 1 January 2026.
How is age calculated for someone born on 29 February?
In years that have no 29 February, this calculator counts 28 February as the birthday, so the person completes another year on 28 February. Some legal systems use 1 March instead, so check local rules when it decides a legal age.
Can I use it to find the difference between two dates?
Yes. Put the earlier date in Date of birth and the later date in Age at this date. You get the difference in years, months and days as well as total months, weeks and days. If the first date is after the second, the calculator shows an error instead of a negative age.
What weekday was I born on?
The coloured result box shows the full date of birth with its weekday, for example "Born on Saturday, 1 January 2000". The next birthday box also tells you which weekday your next birthday falls on.
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