Age Calculator
Enter a date of birth to get exact age in years, months, and days, plus total days lived and a countdown to your next birthday.
Formula verified July 2026
Your age
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How this age calculator works
Enter a date of birth and the date you want to calculate age as of (defaulting to today), and this tool works out the exact age in years, months, and days, along with total days and weeks lived and a countdown to the next birthday.
How age is calculated
Age isn’t just today’s year minus the birth year; that only works if the birthday has already happened this year. The accurate method compares full dates:
- Subtract the birth year from the current year to get a starting age.
- If the current month and day haven’t reached the birth month and day yet, subtract 1 year.
- Calculate the remaining months and days separately, borrowing from the previous month when the day count goes negative.
Worked example
Someone born on June 15, 1995, calculating their age as of July 23, 2026:
- Years: 2026 minus 1995 = 31 (their June birthday has already passed this year, so no adjustment needed)
- Months: July minus June = 1 month
- Days: 23 minus 15 = 8 days
- Result: 31 years, 1 month, 8 days old
- Total days lived: approximately 11,362 days
Common age calculation mistakes
- Simple year subtraction without checking whether the birthday has occurred yet this year, which can be off by a full year.
- Ignoring leap years when counting total days lived over long spans.
- Miscounting days in a partial month instead of borrowing correctly from the previous month’s day count.
- Confusing age as of a specific date with age today when calculating age for a past or future reference date, like an eligibility cutoff.
Common uses for an age calculator
- Checking eligibility for age-restricted programs, school enrollment cutoffs, or retirement benefits.
- Calculating age as of a specific legal or medical reference date rather than today.
- Finding out exactly how many days until your next birthday.
- Working out the exact age difference between two people.
Why is my age different from just subtracting birth year from current year?
Simple subtraction only works if your birthday has already happened this year. If it hasn’t, you need to subtract one more year, since you haven’t reached that birthday yet.
How many days old am I?
Enter your date of birth with today’s date as the reference date, and the calculator shows your total days lived alongside your age in years, months, and days.
Can I calculate someone’s age as of a future or past date?
Yes. Set the reference date field to any date, past or future, to see what someone’s exact age was or will be on that date.
Does this account for leap years?
Yes. The calculator works with actual calendar dates, so leap years are automatically accounted for in both the age breakdown and the total days lived.