Enter a date of birth to see your exact age in years, months and days. It also shows your age in total days and weeks, and how many days until your next birthday.
Results are estimates for planning. Check the figures before you make a financial or health decision.
How the Age works
The calculator compares your date of birth with a second date, which defaults to today. You can change the second date to find someone’s age on any day, past or future.
- It subtracts the years, months and days in turn. If the day is lower than the birth day, it borrows days from the previous month. If the months are negative, it borrows a year.
- Total days is the exact number of calendar days between the two dates, and total weeks is that divided by seven, rounded down.
- Days to next birthday counts forward to the next occurrence of your birth date. If your birthday is on the ‘as of’ date, it shows 0 days.
The result relies on calendar dates only, so time of birth and time zones are not included. The second date cannot be earlier than the date of birth.
Leap-day birthdays follow the browser’s date rules, so check the result if you were born on 29 February.
Tips and common mistakes
Use the ‘age on’ box to check eligibility on a particular date, such as the age on the first day of a school year or a deadline. Check the date format carefully, as swapping day and month changes the result. For official purposes, such as pensions, rely on the date shown by the relevant authority. For the gap between any two dates, use the days between dates tool.
Frequently asked questions
How is my exact age worked out?
The tool subtracts your birth date from the chosen date in years, months and days, adjusting for the number of days in the previous month where needed.
Can I find my age on a past or future date?
Yes. Change the ‘Age on’ date. It defaults to today, but you can enter any date on or after the date of birth.
How are leap-year birthdays handled?
The calculation uses calendar dates, so someone born on 29 February is counted by those dates and the result can vary slightly between leap and non-leap years. Check the date if it matters.