Age Calculator: Exact Age in Years, Months and Days

How the Age Calculator works

Type a date of birth and the calculator shows your exact age in years, months and days, your age in total months, weeks, days, hours, minutes and seconds, how long until your next birthday and which weekday it falls on, the weekday you were born, upcoming milestones and your age on other planets. Change Age on to see how old someone was (or will be) on any other date. Everything is worked out in your browser; nothing you type is sent anywhere.

Dates in almost any format

You can type 1990-03-15, March 15, 1990, 15 March 1990, 15-Mar-1990, 15.03.1990, 19900315 or 3/15/90. When a date written only with numbers could be read two ways (03/04/1990), the calculator follows the choice under Dates typed with numbers: month first, as in the US, or day first, as in most other countries. A two-digit year is never put in the future, so 90 means 1990.

How years, months and days are counted

Your age goes up by one month on the same day number each month, and by one year on your birthday. The days are what is left since the last month-anniversary. Born on 31 January? There is no 31 February, so the calculator counts that month on the last day of February (or, if you pick the other rule, on 1 March). Weeks, days and months are calendar counts, so daylight-saving changes never change them. Hours, minutes and seconds are real elapsed time: add your time of birth and its time zone for exact numbers; without a time, the count starts at midnight at the start of your birth day in your own time zone.

Born on 29 February?

A leap-day birthday only exists in leap years. In other years most people celebrate on 28 February or 1 March, and the law, where it says anything at all, differs from place to place: Hong Kong law, for example, says a person born on 29 February reaches a given age on 1 March in a common year, while rules that count to "the last day of the month" give 28 February. The calculator lets you choose, shows both dates, and counts how many real 29 Februaries you have had. Remember that 1900 was not a leap year but 2000 was: century years are only leap years when they can be divided by 400.

Questions

How do I calculate my age by hand?

Subtract your birth year from the current year, then take one off if your birthday has not happened yet this year. For months and days, count whole months from your last birthday to today, then the days left over.

How many days old am I?

The "days" tile in Your age in total counts every day from your birth date to the Age on date (the birth day itself is day 0). 10,000 days is about 27 years and 4 months, a popular milestone to celebrate.

When will I be one billion seconds old?

A billion seconds is about 31 years and 8 months. The Milestones table shows the exact date (and the time, if you added your time of birth), together with 10,000 days, 500 months, 1,000 weeks and more.

How are dog years worked out?

The old rule of thumb is "one dog year = seven human years". A 2019 study of Labrador retrievers (Wang et al.) suggested human age = 16 × ln(dog age) + 31 instead, because dogs grow up fast and then age more slowly. It is only an approximation, fitted on one breed, and not meant for puppies under one year. The page shows both the formula and the old rule.

What is my age on other planets?

Your age in days divided by how long that planet takes to go round the Sun once (its sidereal year). On Mercury a year is 88 Earth days, so you are about four times older there; on Neptune a year is almost 165 Earth years.

Which zodiac sign and Chinese animal am I?

The sign uses the usual newspaper dates; a birthday right at the change between two signs can belong to either, depending on the year and the time of birth, so use the Zodiac & Birth Chart page for an exact answer. The Chinese animal follows the Chinese New Year, which falls between 21 January and 20 February, so someone born in January or early February belongs to the previous year's animal.

How do I find when one person is twice as old as another?

Use Age difference between two people. The older person is twice the younger's age when the younger one is exactly as old as the gap between them, so for a 30-year gap that is when the younger turns 30.

Is my data saved?

Your last date and the names in My people are kept in this browser's local storage only. Share links contain just the birth date and the Age on date, nothing else.

More from MES