Age Calculator

This age calculator takes a date of birth and, using today as the reference, gives your exact age in years, months and days. It also shows how many days you have been alive, how many days remain until your next birthday, what day of the week you were born on, and your zodiac sign and Chinese zodiac animal. It is handy for checking an age in completed years, working out a baby's age in months and days, finding which weekday a birth date fell on, or simply satisfying curiosity. Please note what it does and does not do: it works from the Gregorian calendar, counts age in completed years rather than the traditional East Asian 'nominal age', and takes the Chinese zodiac animal from the lunar year (switching at Lunar New Year), so someone born in January or early February before the festival gets the previous year's animal, as the limits section explains.

How to use it

1. Choose your 'Date of Birth'. The page starts with 2000-01-01. Use the date picker or type the date in.
2. 'Your Age' immediately shows 'X years, Y months, Z days'.
3. The cards below show 'Zodiac Sign', 'Chinese Zodiac', 'You were born on a' (the weekday), 'Days Alive' and 'Days Until Next Birthday'.
4. If the date is later than today, or the field is empty, the page shows 'Please enter a valid date of birth'.
5. To check someone else, just change the date. There is no button to press, and a refresh restores the default input.

A worked example

Take a birth date of 1990-08-31 and open the page on 13 October 2026. The tool's own algorithm returns 36 years, 1 month, 12 days; 13,192 days alive; 322 days until the next birthday (2027-08-31); born on a Friday; zodiac sign Virgo; Chinese zodiac Horse. The age is worked out like this: subtract the birth year from the current year, then compare months and days. If the day is too small, one month is borrowed and the length of the previous month is added to the days; if the month goes negative, one year is borrowed as 12 months. This is the common calendar-style method. Open the page on another day and the numbers will, of course, change.

Supported scope and known limits

• Only Gregorian birth dates are supported, and age is counted in completed years. Nominal age and lunar birthdays are not produced.
• The Chinese zodiac animal follows the lunar year, which switches at Lunar New Year: someone born before the festival belongs to the previous year's animal. For example the default 2000-01-01 shows Rabbit, because Lunar New Year in 2000 fell on 5 February; Dragon starts from 2000-02-05. The lunar year is converted with the same lunar-calendar library the site uses.
• Zodiac signs use the usual Gregorian boundaries (Virgo runs from 23 August to 22 September). Sources differ by a day at the edges, and the tool does not consider time of birth or time zone.
• 'Days Alive' is the whole number of days, rounded down, between this moment and midnight at the start of the birth date. Time of birth is not considered.
• 'Days Until Next Birthday' is counted by calendar date (from midnight): if today is your birthday it shows 0 days.
• For people born on 29 February, the next birthday in a non-leap year is counted as 1 March.
• 'Today' comes from your device clock. If the device date is wrong, the results will be too.

FAQ: Why is my age different from the number I normally say?

The tool gives completed years: you add one on each anniversary of your birth. If you are used to nominal age (1 at birth, plus one at each Lunar New Year), your number will usually be 1 or 2 higher than the one shown here. Official documents, insurance, school and job requirements are normally based on completed years, but check the exact rule with whichever organization is asking.

FAQ: How does the 'years, months, days' borrowing work?

When today's day-of-month is smaller than the birth day, one month is borrowed and the number of days in the previous month is added. When the month difference is negative, one year (12 months) is borrowed. For someone born on 31 August and calculated on 13 October, the days cannot cover it, so the month count is one lower and the days include September's 30. This is the most common calendar approach, though different programs can differ by a day around month ends.

FAQ: How is the weekday of birth determined?

It comes from the date's weekday in your local time zone using the browser's built-in date functions. The code parses the date in a way that avoids the one-day shifts time zones can cause, so choosing 1990-08-31 gives Friday wherever you are.

FAQ: Can I use it for a baby's age in months?

Yes. For a child under one year the years show 0, and the months and days are the useful part. Whether to use a corrected age for a premature baby is a medical judgement, so follow your doctor's advice. The tool calculates from the birth date only.

Privacy and processing

The date of birth is used only inside your browser. The page's code has no request that sends it to a server and does not save it to local storage. Refreshing or closing the page clears the input.