qcalculate

Age Calculator

Find an exact age in years, months and days, on today’s date or any other, with the total in days and weeks, the next birthday and the day of the week someone was born.

Age

36 years

The age is 36 years, 5 months and 17 days.

Show me how

All steps as text

    Tip: press ← and → to move between steps, or click any step.

    How age is worked out

    1. Whole years: count the birthdays so far. Born on 15 May 1990, someone has had 36 birthdays by 1 November 2026, the last on 15 May 2026.
    2. Whole months: from the last birthday, count the whole months: 15 May to 15 October 2026 is 5 months.
    3. Days: count the days that are left: 15 October to 1 November is 17 days.

    So the age is 36 years, 5 months and 17 days. When the birthday is the 29th, 30th or 31st of a month, a shorter month uses its last day instead: one month after 31 January is 28 February (29 in a leap year).

    Age in days

    Most years have 365 days and leap years have 366. A leap year is one divisible by 4, except century years, which must be divisible by 400: 2000 was a leap year, but 1900 wasn’t. From 15 May 1990 to 15 May 2026 is 36 × 365 = 13,140 days plus 9 leap days, and the 170 days since the last birthday make 13,319 days in all.

    Birthdays on 29 February

    Someone born on 29 February has a real birthday only once every four years. In other years this calculator counts the birthday on 28 February. Some people celebrate on 1 March instead, and some countries’ laws pick one or the other for legal ages, so check if it matters for a document.

    Questions

    How do I calculate my age in Excel or Google Sheets?

    With the date of birth in A2, =DATEDIF(A2, TODAY(), "Y") gives the whole years, "YM" the months after that and "MD" the days. =TODAY()-A2 gives the age in days.

    How many days old am I?

    Enter your date of birth: the calculator shows the age in days and in weeks, counting every leap day since you were born.

    Can I find my age on a past or future date?

    Yes. Change the “Age on” date to any date after the date of birth, for example to see how old you will be on a trip, or how old someone was at an event.

    Does the time of day or time zone matter?

    Not here: the calculator counts whole calendar days. Someone born late in the evening in one time zone may already be a day older in another, but for ages in years, months and days it makes no difference.