How Age Is Calculated (and Why It Can Be Tricky)
Working out your age sounds simple, but doing it exactly, down to months and days, involves months of different lengths and leap years. This calculator handles all of that and also shows your age in weeks, days and hours, the weekday you were born, and how long until your next birthday.
How the calculation works
The calculator counts whole years first, then whole months, then the remaining days. For example, from 15 June 1995 to 19 October 2026 is 31 years, 4 months and 4 days. Totals such as days and weeks are counted from the exact number of calendar days between the two dates, including leap days.
Month-end and leap-year birthdays
If you were born on the 31st and a month only has 30 days, the calculator treats the last day of that month as your "month-day". For people born on 29 February, the birthday in non-leap years is shown on 28 February, which is a common convention.
Uses of an age calculator
- Checking eligibility for exams, jobs, visas or competitions with an age limit on a specific date
- Filling in forms that ask for age in years and months
- Finding the age difference between two people
- Planning milestone birthdays and anniversaries
- Fun facts, like how many days you've been alive
Age on a specific date
Many applications, such as government job adverts and school admissions, require a certain age on a cut-off date, not today. Change the "Age on this date" field to that cut-off date to see your exact age then.
Different ways of counting age
This calculator uses the international method, where you are 0 at birth and gain a year on each birthday. Some cultures count age differently, for example starting at 1 at birth. Official documents almost always use the international method.
Need the number of days between any two dates, or a date a certain number of days from now? Use our date calculator.