How to calculate your age
Your age is the number of whole years since your birth date, plus the months and days left over. Count the years first, then the months, then the days.
Skip the maths and use the age calculator
The formula
Age = whole years since birth date, then remaining whole months, then remaining days.
Step by step
- Take your birth date and the date you are counting to.
- Count whole years until the last birthday on or before that date.
- Count whole months from that birthday.
- Count the days left over.
Worked example
Born 14 March 1990, counted to 17 September 2026
- Last birthday before the date: 14 March 2026, so 36 whole years
- 14 March to 14 September is 6 whole months
- 14 September to 17 September is 3 days
The age is 36 years, 6 months and 3 days.