Age Calculator

An Age Calculator is a comprehensive date-based tool that computes your exact age down to the day and provides a wealth of additional time-related information. Enter your date of birth and instantly see your age broken down into years, months, and days, along with the total number of days, hours, and minutes you have been alive. The tool also counts down the days until your next birthday so you always know how far away your celebration is. Beyond the numbers, it tells you which day of the week you were born on, your Western zodiac sign based on your birth month and day, and your Chinese zodiac animal based on your birth year. For those who need to measure the time between any two dates — not just birth to today — the bonus date interval calculator handles that as well, showing years, months, days, and total days between any pair of dates. The calculator correctly handles leap years, varying month lengths, and edge cases like being born on February 29. All processing happens entirely in your browser using the native JavaScript Date API, so your personal date of birth is never transmitted to any server.

Select your date of birth using the date picker at the top of the tool. As soon as you choose a date, all results update instantly: your exact age in years, months, and days; the total days, hours, and minutes lived; the number of days until your next birthday; the day of the week you were born; your Western zodiac sign; and your Chinese zodiac animal. To calculate the interval between two arbitrary dates, scroll down to the Date Interval section, pick a start date and an end date, and the tool will display the difference in years, months, days, and total days.

The age calculation subtracts the birth date components (year, month, day) from today's date, borrowing from months and years when the day or month of the current date is earlier than the birth date — the same way you would calculate age by hand. Total days are computed by dividing the millisecond difference between the two Date objects by 86,400,000 (milliseconds in a day). The zodiac sign lookup compares the birth month and day against the standard date ranges for each of the twelve Western zodiac signs. The Chinese zodiac is determined by the birth year modulo 12, mapped to the traditional twelve-animal cycle. Leap years are handled natively by the JavaScript Date constructor.