Updated June 17, 2026
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To find someone's age, subtract their birth year from the current year. If their birthday has not yet occurred this year, subtract one more. Someone born on September 14, 1990 turns 36 in 2026 (2026 - 1990 = 36), but on June 18, 2026 they have not reached that birthday yet, so they are still 35.
The step-by-step formula
1. Subtract birth year from current year.
2. Check whether the person's month and day have passed yet in the current year.
3. If yes, that difference is their age. If no, subtract 1.
Example: how old is someone born in 2007?
In 2026, someone born on March 3, 2007 is 19 (2026 - 2007 = 19, and March 3 has already passed by June). Someone born on December 1, 2007 is still 18 as of June 2026, because their birthday is later in the year.
Age in Excel
In Excel or Google Sheets, the quickest formula is =DATEDIF(A1,TODAY(),"Y") where A1 holds the birth date. This returns complete years automatically. The YEARFRAC function gives age in fractional years if needed.
Age in exact days
For legal or medical precision, age in days is simply (today's date - birth date). Most spreadsheets compute this automatically when you subtract two date cells and format the result as a number. The Date Calculator does this for any two dates in seconds.
Age from date of birth calculator shortcut
The fastest option is the Age Calculator above. Enter the birth date and it handles the leap year check and the birthday-passed adjustment automatically, returning exact years, months and days.
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Instant answers for any percentage problem: find the percent, the part, or the whole in one click.