Mathematics
Age Calculator
Calculator
Enter your date of birth and this calculator will work out your exact age in years, months, and days as of today. Useful for birthday planning, legal age verification, medical forms, and retirement calculations.
Formula
Formula
Age = Today − Date of Birth
The calculator subtracts the date of birth from today's date to compute whole years. It then calculates remaining months and days for the fractional part. Leap years and variable month lengths are handled correctly using calendar arithmetic.
Worked example
Someone born on March 15, 1990 wants to know their age today (March 23, 2026).
- 1.Years: 2026 − 1990 = 36 (birthday on March 15 has already passed in 2026)
- 2.Months: March 15 to March 23 = 0 extra months
- 3.Days: 15 to 23 = 8 extra days
- 4.Total months lived: 36 × 12 = 432 + 0 = 432 months
- 5.Total days lived: approximately 36 × 365.25 ≈ 13,149 days
Age: 36 years, 0 months, 8 days. Total: 432 months, ~13,157 days.
Assumptions and limitations
- Age is calculated as of today's date in the user's local timezone.
- Leap year birthdays (Feb 29) are treated as March 1 in non-leap years for comparison.
- Month values use actual calendar month lengths (28–31 days).