Age calculator
Your age
- Years
- Months
- Days
Total days
Next birthday
Gregorian calendar. Today follows Indian Standard Time.
How your age is calculated
Age is a calendar interval, not the number of days divided by 365. Choose your date of birth and the date you want to measure it against.
Years, months and days
The calculator counts complete calendar months from your birth date, then the remaining days. Twelve complete months make one year. When the birth day does not exist in the target month, the last day of that month is used.
Age = Complete years + Remaining months + Remaining days
- Start with your date of birth.
- Find the latest whole-month anniversary that is on or before the age-on date.
- Split the complete months into years and months, then count the days left.
From 15 January 2000 to 2 November 2026, the age is 26 years, 9 months and 18 days.
31 January to 28 February in a non-leap year is one calendar month under this method. The calculation uses Gregorian dates, not Hijri dates.
Total days
Total days counts calendar-day boundaries between the two dates. The birth date is day zero. Leap days are included; time of birth is not used.
Total days = Age-on date − Date of birth
- Convert both dates to consistent UTC day numbers.
- Subtract the birth day number from the age-on day number.
- Keep the count as a whole number, without dividing by an average year length.
From 28 February 2024 to 1 March 2024 there are 2 days, because 2024 includes 29 February.
The Today button follows Indian Standard Time (Asia/Kolkata). Calendar arithmetic uses dates, so daylight-saving changes do not add or remove a day.
Your next birthday and leap-day births
The next birthday is the first birthday on or after the age-on date. If it falls on that date, the calculator shows that your birthday is today.
Days until birthday = Birthday date − Age-on date
- Use the birth month and day in the age-on year.
- For 29 February in a non-leap year, use 28 February.
- If that date has passed, use the next year.
Someone born on 29 February 2000 is 25 years old on 28 February 2025 under this calendar convention.
The February 28 convention is used consistently for age and birthday dates. Legal eligibility rules can differ. Dates from years 0001 to 9999 are supported; an upcoming birthday beyond that range is not displayed.
Calendar reference: US Naval Observatory: Gregorian leap years