Age Calculator

Forms, visas, and school records ask for an age on a specific day, not a rough guess. Age Calculator counts calendar years, months, and days from a date of birth.

How the count is built

Enter the birth date. Leave “As of” empty to use today, or pick another date when the form says “age as of.” The result is years, then leftover months, then leftover days, plus a total-day count. If the day of the month has not been reached yet, the calculator borrows from the previous month and uses that month's length, so February and 31-day months are not treated as 30 days. If the as-of date is before the birth date, the page reports an error instead of a negative age. Date Difference is the tool when you want the span between two dates that are not a birthday.

What the total days mean

Total days is the whole number of 24-hour periods between the two dates in your browser's local calendar. It is not an hour-and-minute age, and a time of birth is not an input. A person born late on the birthday still shows the same calendar age as someone born at midnight. Week Number answers a different question, the ISO week of a date. Countdown Timer counts down to a future moment in days, hours, minutes, and seconds. Use that when the question is “how long until,” not “how old.”

What this tool will not do

It will not convert age to hours, include time zones, or adjust for a birth time. It will not estimate a life expectancy or a retirement date. The optional as-of field is a date, not a clock time. Numbers stay in this browser tab. Percentage Calculator is for percents, not dates. If you only need the gap in weeks, Date Difference lists days, weeks, hours, and minutes between two dates.