Age Calculator in Years, Months and Days
Type in a date of birth and get the exact age, years, months and days, not just a year count, as of today or any date you pick, or use it as a date difference calculator including end date to count the exact days between any two dates. You also get the total days lived and a countdown to the next birthday. Most people land here because a form is asking for an exact age, or because a birth certificate gives only the date and the maths would otherwise be done by hand. It handles leap year birthdays on 29 February correctly and works for any calendar date, past or future.
Related reading: Guide: how to calculate age
Last updated: October 22, 2026
Your result
The formula
Age = the calendar difference between the date of birth and the chosen date, carried as years, then months, then days, not a simple day count divided by 365.25
A worked example
Someone born on 14 March 1990, checked on 25 September 2026, is 36 years, 6 months and 11 days old, or 13,344 days.
More about the Age Calculator
Where an exact age actually matters
Most people reach for an age calculator because a form demands precision: passport and driving licence applications, insurance quotes, pension and retirement eligibility, school admission cutoffs, and youth sports age groups all work off exact years, months and days, not "about 34". Getting it wrong by a month can mean a rejected application or a child placed in the wrong school year, so the boring exactness is the whole point. The "as of" date matters just as much: eligibility is almost always judged at a fixed cutoff date, and a birthday falling a week after the cutoff changes the answer completely.
The maths, if you ever need it by hand
Subtract the birth year from the target year, then subtract one more year if the birthday hasn't happened yet this year. That check is where most mental maths goes wrong. For the months and days, work with real calendar months rather than dividing a day count by 30 or 365: February has 28 days, leap years add a 29th, and a "divide by 365.25" shortcut drifts by days over a lifetime. The calculator above does the calendar carrying properly, including 29 February birthdays, which is exactly the fiddly bit nobody wants to do twice.
How to use the Age Calculator
- Enter the date of birth.
- Leave the "as of" date on today, or pick another date to check the age at a specific point.
- Hit Calculate for the age in years, months and days, the total days lived, and the countdown to the next birthday.
Frequently asked questions
Why does this give a different answer to just subtracting the birth year?
Subtracting years only works if the birthday has already happened this year. This calculator carries the full year month day difference, so it correctly accounts for whether the birthday has passed yet, and gives the months and days on top of the years.
How does the leap year on 29 February get handled?
The calculation carries actual calendar months and days, so a birth date of 29 February ages normally against 28 February or 1 March in non leap years and returns to the 29th every leap year. It is not skipped or double counted.
How many days old am I?
Enter your date of birth and this age calculator shows your total days lived, alongside the years, months and days breakdown. It counts real calendar days including leap years, so the figure is exact for the date you choose.
How old will I be in 2030?
Subtract your birth year from 2030, then subtract one more year if your birthday hasn't happened yet that year. Someone born in March 1998, for instance, turns 32 in March 2030, but is still 31 for the first two months of the year.
How do I calculate age in total months?
Multiply the full years by 12 and add the extra months, a child who is 4 years and 7 months old is 55 months old. Paediatricians and nursery admissions in the UK and US often ask for age this way, since a few months makes a big developmental difference in young children.
How many days are left until my next birthday?
Count forward from today to the same month and day next occurrence, if today is 26 September and your birthday is 14 February, that's about 141 days away. It's the same date difference math our calculator runs, just anchored to a future date instead of the past.
What is the difference between chronological and biological age?
Chronological age is the exact time elapsed since your birth, what this calculator shows. Biological age estimates how old your body seems based on health markers, which can differ.
How do I calculate age from a birth date by hand?
Take the current year minus the birth year, then subtract one more year if the birthday has not happened yet this year. Born in June 1990 and checking in October 2026: 2026 minus 1990 is 36, the birthday has passed, so 36. For the months and days on top, the calculator above does the calendar carrying for you.
How old am I exactly in years, months, and days?
Our age calculator gives your exact age down to the day, plus fun stats like total days lived. Just enter your birth date, it takes two seconds.
What is Korean age and how is it calculated?
In the traditional Korean system you are 1 year old at birth and everyone gains a year together on January 1st, the formula is: current year − birth year + 1. Since June 2023 South Korea uses international age for all official purposes, but traditional Korean age is still common in everyday conversation and social seniority.