Age Calculator — Free Online
Calculate your exact age in years, months, and days from your date of birth. Accurately handles leap year birthdays and shows days until your next birthday.
How to Use the Age Calculator
- Enter your date of birth using the date picker — any date from year 1 to today is supported
- The calculator uses today's date automatically as the reference point
- Click "Calculate My Age" to see your exact age in years, months, and days
- Your total days lived and days until your next birthday are shown automatically
- Copy any result with the copy button for use in documents or forms
How the Age Calculator Works — The Formula
Age is calculated by finding the difference between the birth date and the reference date (today) in years, months, and days using the proleptic Gregorian calendar. The calculation correctly handles February 29 birthdays — in non-leap years, the birthday is treated as March 1.
Age = (Reference Date) − (Birth Date)
Years = complete 12-month periods elapsed
Months = complete calendar months after last birthday year
Days = remaining days after last complete month
Total Days = JDN(Reference Date) − JDN(Birth Date)
Days to Next Birthday = JDN(Next Birthday) − JDN(Today)
Formula validated by Vipul Jaganiya, Computer Science expert in Calendar Mathematics and Timezone Engineering. Leap day birthdays (Feb 29) use March 1 convention in non-leap years, matching most legal jurisdictions.
Real-World Examples
| Date of Birth | Person | Age (as of 2026-05-26) | Total Days |
|---|---|---|---|
| 1879-03-14 | Albert Einstein | 147 years, 2 months, 12 days | 53,795 days |
| 1955-10-28 | Bill Gates (example) | 70 years, 6 months, 29 days | 25,778 days |
| 2000-01-01 | Born on Y2K | 26 years, 4 months, 25 days | 9,642 days |
| 1991-10-05 | Born Oct 1991 | 34 years, 7 months, 21 days | 12,651 days |