Age Calculator

Yes, the calculation uses precise calendar logic that accounts for the varying number of days in each month and the occurrence of leap years every 4 years (leap years add an extra day on February 29). The calculator automatically handles leap years when calculating date differences, ensuring accurate age calculations even for birthdays near February 29. For example, someone born on February 29 will have their birthday calculated correctly in both leap years and non-leap years (typically February 28 or March 1 in non-leap years, depending on legal definition). Understanding leap year handling helps you see why the calculator provides accurate results.

Total weeks is calculated by taking the total number of days difference between birth date and target date, then dividing by 7 and rounding down to the nearest full week (TotalWeeks = floor(TotalDays ÷ 7)). This gives you the number of complete weeks lived, regardless of year or month boundaries. For example, if you've lived 12,492 days, that equals 1,785 complete weeks (12,492 ÷ 7 = 1,785.14, rounded down to 1,785). Understanding total weeks calculation helps you see how cumulative time metrics work.

Some calculators approximate a month as 30.44 days (average month length), which can cause slight differences in total months calculations. This tool calculates precise calendar months based on the specific dates involved using differenceInMonths function, which accounts for varying month lengths (28–31 days). For example, passing February counts as 1 month just like passing August, despite different day counts (February has 28–29 days, August has 31 days). Understanding precise month calculation helps you see why this calculator provides accurate results.

Yes, as long as the dates are valid Gregorian calendar dates. Currently, this tool supports standard modern calendar dates (Gregorian calendar system). The calculator can handle dates from the adoption of the Gregorian calendar (1582) onwards. For dates before 1582 or for other calendar systems (Julian calendar, lunar calendars, etc.), you would need specialized calendar conversion tools. Understanding historical date support helps you see when this calculator is appropriate to use.

The age calculation is highly accurate for standard Gregorian calendar dates. It uses precise date difference algorithms (differenceInYears, differenceInMonths, differenceInDays) that account for leap years, varying month lengths, and calendar complexities. The calculator provides exact age in years, months, and days based on the specific dates entered. However, for legal age verification or high-stakes age determination, you should consult professional legal services, as real-world age verification may involve time zones, legal definitions, and other factors beyond this calculator's scope.

The calculator will show an error message: "Target date represents a time before birth date." This prevents invalid calculations where the target date is earlier than the birth date. Age calculation requires the target date to be on or after the birth date. If you need to calculate time until a future event, you would reverse the dates (use future date as target date, current date as birth date equivalent). Understanding date validation helps you see why the calculator prevents invalid inputs.

The calculator handles February 29 birthdays automatically using date-fns library, which maps February 29 to February 28 in non-leap years (standard convention). When calculating next birthday for someone born on February 29, the calculator will use February 28 in non-leap years. Some legal systems use March 1 instead, but this calculator follows the February 28 convention. Understanding February 29 handling helps you see how the calculator manages special date cases.

Age breakdown shows precise age in years, months, and days (e.g., 34 years, 2 months, 5 days), representing full periods completed from birth date to target date. Total metrics show cumulative time regardless of year/month boundaries (e.g., 12,492 total days, 1,785 total weeks, 410 total months). Age breakdown is more intuitive for expressing age in everyday conversation, while total metrics are useful for precise time measurements and calculations. Understanding this difference helps you see when to use each metric.

Western zodiac signs are determined by month and day ranges (12 signs: Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn, Aquarius, Pisces). For example, January 1–19 is Capricorn, January 20–February 18 is Aquarius, etc. Chinese zodiac signs are determined by birth year in a 12-year cycle (12 animals: Rat, Ox, Tiger, Rabbit, Dragon, Snake, Horse, Goat, Monkey, Rooster, Dog, Pig). The calculator uses these standard definitions to determine zodiac signs. Understanding zodiac determination helps you see how astrological information is calculated.

This calculator is designed for planning and educational purposes only, not for legal age verification or high-stakes age determination. While the calculator provides accurate age calculations, real-world legal age verification involves considerations beyond this calculator's scope: legal age definitions (age of majority, voting age, drinking age vary by jurisdiction), time zones (birth location vs current location), calendar systems (some jurisdictions use different calendars), and other legal factors. For legal age verification, consult licensed legal professionals and use official age verification services. Understanding calculator limitations helps you see when professional services are needed.

To calculate age difference between two people, enter each person's birth date separately using the same target date (typically today), then compare the age results. The age difference is the difference in years, months, and days between the two ages. For example, if Person A is 34 years, 2 months, 5 days old and Person B is 28 years, 6 months, 10 days old, the age difference is approximately 5 years, 7 months, 25 days (calculated by subtracting Person B's age from Person A's age). Understanding age difference calculation helps you see how to compare ages between people.

The calculator uses the date values you enter without time zone information (dates are treated as local dates, not UTC or specific time zones). It calculates age based on calendar dates only, not precise timestamps. For most purposes, this is sufficient, but for precise age calculations that require time zone consideration (e.g., someone born in one time zone calculating age in another time zone), you would need specialized time zone-aware tools. Understanding time zone handling helps you see when this calculator is appropriate to use.