Age Calculator
Find your exact age in years, months, and days from any birth date.
Enter your date of birth to calculate your exact age.
Your age is the number of complete years since your birth, then the leftover whole months, then the leftover days. Enter your date of birth and the calculator counts up to today (or any date you pick). Someone born 2000-01-15 would show their finished years, then the extra months and days — for example 26 years, 5 months, 11 days — plus the total days lived.
How exact age works
Everyday age is a whole number — the count of birthdays you have already passed. The exact age adds two more pieces: the number of full months since your last birthday, and the number of days since that month mark. The calculator subtracts your birth date from the target date one component at a time, borrowing from the next larger unit whenever a piece comes out negative, just like long subtraction.
- 1 Subtract the years. Target year minus birth year gives a first guess at your age in years.
- 2 Subtract the months. Target month minus birth month. This can be negative — that is fine for now.
- 3 Subtract the days. Target day-of-month minus birth day-of-month, which can also be negative.
- 4 Borrow for negative days. If the day difference is negative, drop one month and add the number of days in the month just before the target date.
- 5 Borrow for negative months. If the month difference is now negative, drop one year and add 12 months. What remains is your exact age in years, months, and days.
- 6 Count total days. Separately, take the whole-day gap between the two dates to get the total number of days you have lived.
Days lived at a glance
Approximate whole-day totals; exact figures depend on how many leap days fall in the span (one extra day roughly every four years).
| Age | About this many days | Note |
|---|---|---|
| 1 year | ≈ 365 days | 366 in a leap year |
| 10 years | ≈ 3,652 days | includes 2–3 leap days |
| 18 years | ≈ 6,575 days | common legal adulthood |
| 25 years | ≈ 9,131 days | ≈ 6 leap days |
| 50 years | ≈ 18,262 days | ≈ 12 leap days |
| 100 years | ≈ 36,525 days | century leap rules apply |
Edge cases and how they are handled
Leap-year birthdays (Feb 29). If you were born on 29 February, your birthday only lands on the calendar in leap years. In common years the calculator still advances your age once you pass 28 February → 1 March, so you never lose a year.
Age counts completed time. You are “26” until the moment your 27th birthday arrives — the calculator never rounds up early, so a near-birthday still reads as the finished age plus the leftover months and days.
Total days is independent of the y/m/d split. Months have different lengths, so the year-month-day breakdown and the raw day count answer two different questions; both are shown so you can use whichever you need.