Age Calculator

How old am I? Using the age calculator

Enter your date of birth as a day, a month and a year. The fields follow the order you are used to: month first in the US, day first in the UK and most other countries. You can also paste a date such as “15 June 1990” or “1990-06-15”. If a pasted date could be read two ways, like 05/06/1990, the calculator asks which one you meant instead of guessing.

The Age on this date field starts at today’s date on your own device, not a server’s clock in another time zone. Change it to find out how old you were, or will be, on any date. Results update as you type: your exact age, totals in months, weeks, days and hours, your next birthday, half birthday, the weekday you were born and milestones such as 10,000 days old.

How age is calculated in years, months and days

The method is the same one you would use with a calendar:

1. Count the whole years from the birth date. Born on 15 June 1990, on 13 November 2026 that is 36 years, reaching 15 June 2026.
2. Count the whole months after that: 15 July, 15 August, 15 September and 15 October 2026 make 4 months.
3. Count the days left: from 15 October to 13 November 2026 is 29 days.

So the age is 36 years, 4 months and 29 days. Each month is counted from the original birth day, not from the end of the previous month, so the answer never drifts. When a month doesn’t have the birth day (there is no 31 April), that month ends on its last day instead. The calculator shows these steps for your own dates under “How we calculated it”.

Why age calculators disagree: the end-of-month problem

A year always means the same thing, but a month can be 28, 29, 30 or 31 days long. That makes some date pairs genuinely ambiguous, and different calculators settle them in different ways. Here are three common cases:

This calculator counts whole months from the birth day and lets short months end on their last day, which is also how the best-known date-duration websites count. Total days never differ between methods, so if you need a single unambiguous number for a form or a contract, use the total in days.

A second source of difference is “today”. Some calculators take today’s date from Greenwich Mean Time. In the evening in the Americas, GMT is already on the next day, so a birthday can appear a day early. This calculator always uses the date on your own device.

Born on 29 February? Leap-day birthdays and the law

People born on 29 February have a real birthday only in leap years, such as 2024 and 2028. In other years most celebrate on 28 February or 1 March. If your date of birth is 29 February, the calculator asks which day to use and applies it to your age, your next birthday and age checks.

The two rules give different answers around the end of February. Born on 29 February 2008, you turn 18 on Saturday 28 February 2026 under the 28 February rule, or Sunday 1 March 2026 under the 1 March rule. There is no single worldwide legal answer: different countries, and even different laws within one country, use different days. If the exact date matters for a licence, a benefit or a contract, check with the organisation involved. The next real 29 February is in 2028.

How many days old am I? Totals, milestones and 10,000 days

Your age in days is simply the number of days from your birth date to today. Leap days are included automatically. The calculator also gives the total in weeks and months, and approximate hours, minutes and seconds counted from midnight. Add your time of birth and the time zone you were born in, and the hours, minutes and seconds become exact and count up live, with daylight saving changes taken into account.

Round numbers make fun milestones. You are 10,000 days old at about 27 years and 4 months, and 1,000 weeks old at about 19 years and 2 months. One billion seconds arrives at about 31 years and 8 months (11,574 days, 1 hour, 46 minutes and 40 seconds after you were born). The milestones list shows the date of each one and how far away it is.

How old was I on a certain date? How old will I be in 2050?

To find your age on a past date, such as the day you started school or got married, change the Age on this date field. For a future date, enter it the same way, for example 1 January 2050. If you only know the years, use the Born in year tab: subtract the birth year from the other year to get the age after that year’s birthday, and take away one for the months before it.

Age difference between two people

The Age difference tab takes two dates of birth and shows who is older and by how much, in years, months and days, and in total days and weeks. You can add names to make the result easier to read. It works for siblings, couples, twins born either side of midnight, or historical figures.

The Age check tab answers questions like “who is old enough to vote on election day?”. Enter a minimum age and a date, and it gives the latest birth date that qualifies. Add a date of birth to get a yes or no, and the date that person reaches the age.

Calculate age in Excel and Google Sheets

Both Excel and Google Sheets have a DATEDIF function. With the date of birth in A2 and today in A3:

• Whole years: =DATEDIF(A2, A3, "Y")
• Months after the last birthday: =DATEDIF(A2, A3, "YM")
• Total days: =A3 - A2

For the leftover days, Microsoft advises against the "MD" option, because it can give a negative number, a zero or an inaccurate result. A safer formula takes the date reached after the whole months away from the end date: =A3 - EDATE(A2, DATEDIF(A2, A3, "M")). Use TODAY() in place of A3 for today’s date, and format the result cell as a number rather than a date.

Last updated: 2026-11-14