How to use Age Calculator
To calculate your age, enter your date of birth using the date picker or type it in YYYY-MM-DD format, then click Calculate. The tool computes your exact age in years, months, and days as of today — accounting for leap years and month-length variations so the calculation is always accurate to the day. Additional panels show your age in total months, total days, total hours, and total seconds since birth.
To calculate someone's age on a specific past or future date (useful for legal age checks, retirement planning, or historical lookups), use the As-of Date field to override today's date. The calculation updates to show how old the person was — or will be — on that particular day. This works for any combination of birth date and target date, forward or backward in time.
Why use our Age Calculator?
- Exact calculation in years, months, and days — correctly handles leap years and month-length differences
- Shows age in multiple units simultaneously: total months, days, hours, and seconds
- As-of date option for calculating age at a past or future date
- Useful for legal age verification, birthday planning, retirement calculations, and historical research
- 100% browser-based — your date of birth is never sent to any server
- Shows total months, days, hours, and seconds alongside the years-and-months result
Frequently Asked Questions
How does the age calculator handle leap years?
Leap years are handled correctly in the date arithmetic. A leap year occurs every 4 years (years divisible by 4), except for century years (divisible by 100) which are not leap years, except for years divisible by 400 which are. So 2000 was a leap year, 1900 was not, and 2100 will not be. If you were born on February 29 (a leap day), your birthday in non-leap years is typically counted as March 1 for age purposes — the tool follows this convention.
Why does the tool show different results than my simple subtraction?
Simple year subtraction (current year minus birth year) ignores whether your birthday has occurred yet this calendar year. If your birthday is in December and today is February, you are still in your current age year — subtracting the years would give a result that's one too high. The tool accounts for the current month and day, giving a precise result. This also explains why your age in 'total days' may differ from years × 365 — months have different lengths and leap years add an extra day every four years.
Can I use this to check if someone is legally old enough?
Yes — enter the person's date of birth and the current date, or a specific as-of date such as when a contract was signed or when an event occurred. The calculated age in years tells you definitively whether the person had reached a specific age by that date. For legal purposes, make sure you are using the correct jurisdiction's definition of age — most use the birthday itself as the qualifying moment, meaning the person is considered to have turned X years old at 00:00:00 on their Xth birthday.
How many seconds old am I?
The total seconds panel shows your age converted to seconds — equal to your total days × 86,400 (the number of seconds in a day). This number grows by 1 every second you're alive. A person who is 30 years old has lived approximately 946,728,000 seconds. The exact number depends on whether those 30 years included leap years and your precise time of birth (the calculator uses midnight on your birth date unless a birth time is specified).