How age is calculated
- Years: how many birthdays have passed. If this year’s birthday is still ahead, this year does not count yet.
- Months: full months since the last birthday.
- Days: the remaining days since the last monthly date of birth.
Example: born July 30, 1985, on October 23, 2026. The 41st birthday was July 30, 2026; two full months bring us to September 30, then 23 more days. Result: 41 years, 2 months, 23 days.
Use “Age on” to find the age at any date, for example on a graduation day, a retirement date or a form deadline.
Fun age milestones
| Milestone | Reached at about |
|---|---|
| 1,000 days | 2 years, 9 months |
| 10,000 days | 27 years, 5 months |
| 1 billion seconds | 31 years, 8 months |
| 20,000 days | 54 years, 9 months |
| 1,000 months | 83 years, 4 months |
To find the exact date of your 10,000th day, use the days between dates calculator: enter your birth date, choose “Add or subtract days” and type 10,000.
Calculate age in Excel
| You want | Formula (birth date in A1) |
|---|---|
| Age in years | =DATEDIF(A1,TODAY(),"Y") |
| Months since last birthday | =DATEDIF(A1,TODAY(),"YM") |
| Remaining days | =DATEDIF(A1,TODAY(),"MD") |
| Age in days | =TODAY()-A1 |
DATEDIF works in Excel but is not listed in the function menu, so type it in by hand.
Frequently asked questions
How old am I if I was born in 1990?
You turn 36 in 2026. Until your birthday this year you are 35. The calculator shows it to the day.
What about birthdays on February 29?
In non-leap years the calculator uses February 28. Some people prefer March 1; the age in years differs by at most one day.
How many days old am I?
See “Days lived”. A 30-year-old has lived about 10,957 days, depending on the number of leap years.
Is my date of birth stored?
No. The calculation runs entirely in your browser.