How the age is worked out
Your age is the number of birthdays you have had. The calculator counts whole years first, then whole months from your last birthday, then the days left over. When a month is shorter than your birth day, the month anniversary falls on its last day, so someone born on 31 January reaches one month on 28 February (29 in a leap year).
Example: born August 15, 1990, on March 10, 2026 the age is 35 years, 6 months and 23 days, which is 12,991 days or 1,855 weeks and 6 days. The next birthday is on August 15, 2026, 158 days later.
Total days and weeks
Total days counts the calendar days from the date of birth up to the chosen date, not including the birth day itself, the same way you would count nights. Weeks are total days divided by 7, with the remainder shown in days.
Born on 29 February
In years without 29 February you can choose whether the birthday falls on 28 February or 1 March. The choice changes the age only on 28 February of a common year, and changes the countdown to the next birthday. Laws and organisations do not all use the same convention.
Privacy
Everything is calculated in your browser. Your date of birth is not sent anywhere and is saved on this device only if you tick the box.