Date and time tool
Calculate an exact age in calendar years, months, and days—with leap years and different month lengths handled for you.
Select the person’s birth date.
Use today or calculate age on another date.
Age result
Your detailed age will appear here
Choose a birth date and the date on which you want to measure the age.
Age guide
Understand why calendar-aware age calculations are more accurate than simply dividing days by 365.
Calendar rule
A leap year has 366 days instead of 365, with an extra day on February 29. It keeps the calendar aligned with Earth’s orbit around the Sun.
Years divisible by 4 are usually leap years.
Century years must also be divisible by 400.
2000 and 2024 are leap years; 1900 and 2100 are not.
February 29
People born on February 29 still become one year older every year. In non-leap years, birthday observance can be February 28 or March 1 depending on personal preference and local legal rules.
This calculator
Uses February 28 as the anniversary reference in non-leap years while retaining the original February 29 birth date.
Helpful answers
Age is calculated as the completed calendar years, months, and days between a birth date and the selected age-at date. The calculator accounts for the actual length of each month.
Yes. A birth date of February 29 is supported. In a non-leap year, this calculator uses February 28 as the displayed birthday reference.
Calendar years can contain 365 or 366 days. Leap years and the different number of days in each month make a direct years-times-365 estimate inaccurate.
Yes. Choose any age-at date on or after the birth date. This is useful for checking age on an application date, event date, or future birthday.
Chronological age is the exact time elapsed since birth, usually expressed in completed years, months, and days. It is different from biological or developmental age.
Practical guidance
Calculate completed age on a selected date, total days and the next birthday. See the calendar rules for leap-day and end-of-month birthdays.
Birth date 15 August 1995 and Age at date 11 September 2026 gives 31 years, 0 months and 27 days. That is 11,350 total days, or 1,621 weeks and 3 days.
A February 29 birthday is clamped to February 28 in a non-leap year. Month additions also clamp to the final valid day and continue from that date. This is a disclosed calendar convention, not a determination of legal age or eligibility.
Years, months and days are a calendar decomposition, not decimal years. Total hours is total calendar days × 24; it does not use a birth time or actual elapsed hours across daylight-saving changes.
Select a birth date and an Age at date on or after it. Use a fixed comparison date to reproduce an example; the initial comparison date comes from your device.
Count completed calendar years, then completed months, then remaining days. Total days uses the difference between the two calendar dates; total weeks is whole days / 7 with a remainder.
Use the application or event date as Age at when checking a dated requirement. Dividing total days by 365 ignores leap days and will not reproduce the completed-year count.
Tools may count months from the original birthday or from each intermediate clamped date. This tool advances from each intermediate date. Check the convention required by the organization using the result.
Guide checked against the web calculator by an automated coding assistant. Independent professional review is not recorded.
Substantive guide update: .