Age Calculator
Calculate exact age in years, months, days and hours.
Overview
The Age Calculator works out how old somebody is right now in years, months, days, hours, and minutes — not just the rounded "you are 34" figure most apps stop at. Enter a date of birth and an optional "as of" date, and the result breaks down the elapsed time into every common unit so you can quote an exact age in a contract, court filing, or birthday card.
Helpful for HR teams checking employment age thresholds, medical staff calculating gestational or paediatric ages, genealogy researchers piecing together family trees, and parents who want a precise "your baby is 14 months and 3 days old" line for a milestone post.
How it works
The calculation uses the proleptic Gregorian calendar via the standard DateTime arithmetic in .NET, taking month and year boundaries into account so February leap days and 30/31 day months do not throw off the count. Years are advanced first, then months, then the remaining days are computed against the actual length of the start month — the same algorithm used by tax authorities and the ISO 8601 duration spec when a duration carries year and month components.
Hours, minutes, and the total-days figure are derived from the difference in ticks between the two timestamps, so daylight saving transitions do not skew the totals when both points are interpreted as local civil time.
Examples
DOB 1990-03-15, as of 2026-05-18
→ 36 years, 2 months, 3 days
→ 13,213 total days
DOB 2024-02-29, as of 2026-02-28
→ 1 year, 11 months, 30 days
DOB 2000-01-01, as of 2026-01-01
→ 26 years, 0 months, 0 days exactly
→ 227,904 total hours
FAQ
How are leap years handled?
Each year boundary is checked against the proleptic Gregorian calendar, so a Feb 29 birthday rolls over on Feb 28 in non-leap years if you want a "completed year" reading, or Mar 1 if you prefer the strict anniversary.
Can I use it for a future date?
Yes. Enter a target date that has not happened yet and the result is a negative or "in N years" reading, useful for retirement and pension planning.
Why are months shown separately from days?
Months have variable length (28–31 days), so collapsing them into days loses meaning. Showing both gives a calendar-accurate breakdown that matches how people naturally describe ages.
Does it account for time zones?
Both timestamps are treated in the same zone you enter them in, so the elapsed duration is independent of where the person lives now.
What if the date of birth is after the target date?
The result swaps direction and reports the time until birth, which is handy for prenatal and due-date estimates.