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Age Calculator

Calculate age or the interval between two dates in years, months, and days — and as total months, weeks, days, hours, minutes, and seconds.

Leave blank to use today's date.

Age

36 years, 7 months, 30 days

Or in months
439 months and 30 days
Or in weeks
1,913 weeks
Or in days
13,391 days
Or in hours
321,384 hours
Or in minutes
19,283,040 minutes
Or in seconds
1,156,982,400 seconds
Age36 years, 7 months, 30 daysView results

Find your exact age, or the interval between any two dates, in years, months, and days. Enter your date of birth and, optionally, the date to measure to — leave it blank to use today. The same span is also shown in total months, weeks, days, hours, minutes, and seconds.

Formula

Age uses the common age system: count whole years and months by the calendar, then add the remaining days.

1. months = (asOfYear − birthYear) × 12 + (asOfMonth − birthMonth)
   if birth + months lands after the comparison date, subtract one month
2. years  = months ÷ 12   (whole)      remaining months = months mod 12
3. days   = comparison date − (birth + whole months)

Whole months are added with day clamping, so January 31 plus one month is the last day of February, and a February 29 birthday completes a year on February 28 in a common year.

To measure the gap between two events, put the earlier date in "Date of Birth" and the later one in "Age at the Date of".

Example

FieldValue
Date of BirthJanuary 1, 1990
Age at the Date ofJune 17, 2026
Age36 years, 5 months, 16 days
Or in months437 months and 16 days
Or in weeks1,902 weeks and 2 days
Or in days13,316 days

Examples

Someone born January 1, 1990 on June 17, 2026

From January 1, 1990 to June 17, 2026 is 36 years, 5 months, and 16 days — the same as 437 months and 16 days, or 13,316 days, or 1,150,502,400 seconds.

A February 29 birthday

A person born February 29, 2000 reaches 25 years, 0 months, 0 days on February 28, 2025, because February 28 is the last day of the month in that common year.

Frequently asked questions

How is age calculated?
Age is the time from your date of birth to a comparison date (today by default), counted in whole years, then whole months, then the leftover days. A month is counted as reaching the same day of the next month — so from the 15th to the 15th is one month — and a year is twelve such months.
How do you count age across months of different lengths?
Whole months are counted by the calendar, not by a fixed number of days. Going from January 31 forward one month lands on the last day of February, and any days past that are counted on top. This matches the common, everyday way people count age.
What happens to a February 29 birthday in a non-leap year?
Because February 28 is the last day of the month in a common year, a person born on February 29 completes another full year on February 28. This calculator treats February 28 as the birthday in non-leap years.
Can I find the difference between two arbitrary dates?
Yes. Set the date of birth to the earlier date and "Age at the Date of" to the later date, and the result is the interval between them — in years, months, and days, plus total weeks, days, hours, minutes, and seconds.
Does this calculator account for the time of day?
No. It works in whole calendar days, so the hours, minutes, and seconds are exact multiples of full days rather than counted from a specific birth time.

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