How do you calculate age from date of birth?
Subtract the birth year from this year, then take away one if this year's birthday has not come yet. That gives full years.
Age Calculator
Enter a date of birth to get the exact age in years, months and days, today or on any date, and the days left to the next birthday.
Date of birth
Age on
Today unless you change it. Set an exam cut-off, a test date or a day ahead.
Enter a date of birth to see the exact age.
Next birthday
Shows once a date of birth is in.
Total age
- Months
- Not yet
- Weeks
- Not yet
- Days
- Not yet
- Hours
- Not yet
- Minutes
- Not yet
Born
- Day of the week
- Not yet
- Star sign
- Not yet
- Generation
- Not yet
First person's birthday
Second person's birthday
Enter them in any order; the older one is worked out for you.
Enter both birthdays to compare them.
Gap in total
- Months
- Not yet
- Weeks
- Not yet
- Days
- Not yet
Ages today
- First person
- Not yet
- Second person
- Not yet
The answer updates as you change either date, so there is no button to press and nothing to reload.
Free with no sign-up, and the birth dates you enter never leave this page.
- Age on any cut-off or test date
- Totals in months, weeks and days
- Age gap between two birthdays
How to calculate age
Work out an exact age from a date of birth in three steps.
Enter a date of birth
Type the birthday or pick it from the calendar. The exact age in years, months and days appears beside it at once.
Set the age at date
Today is filled in for you. Change it to an exam cut-off, a test date or any day ahead to see the age on that day.
Copy your exact age
Copy the age as one line for a form, or read it as total months, weeks and days with the next birthday countdown.
Age calculator as on date
Job and exam forms often ask for your age as on a fixed date, such as 1 January or 1 August of the exam year, not the day you apply. Put that date in the Age on box and the result shows your age on that day, in the years, months and days most forms want.
A single day can decide eligibility. Someone born on 2 August 1996 is still 29 on 1 August 2026, and turns 30 the next day. The calculator counts whole birthdays the way age limits are written, so check the cut-off date and the upper limit in the notice itself.
The same box works for any other date. Pick a day in the future to see how old you will be at a wedding or on retirement day, or a day in the past to find someone's age at a historic event, a graduation or the date on an old document.
Chronological age calculator
Teachers, speech therapists and psychologists need a child's chronological age on the day a test was given, because scores are compared with children of the same age. Enter the birth date, set Age on to the test date, and read the age in years, months and days.
To calculate chronological age by hand, write the test date above the birth date and subtract days, then months, then years. When the days go below zero, borrow a month and add the real number of days in it. The calculator borrows the same way, with leap years included.
Some scoring tables want the age in total months, which is shown below the main result. Test manuals differ on rounding and on which date counts when testing runs over several days, so follow the manual for the test you are scoring when it gives its own rule.
What this online age calculator shows
Years, months and days
Full years first, then whole months, then the days left over, the way forms and reports write age.
Age in days and weeks
Your whole age as a total of months, weeks, days, hours and minutes, counted to the start of today.
Birthday countdown
How many days until your next birthday, the weekday it falls on and the age you are about to turn.
Age gap calculator
Enter two birthdays in any order to see who is older and by how many years, months and days exactly.
What day you were born
The weekday of any birth date, worked out on the calendar in use today, from the year 1 to 9999.
Generation and star sign
Your generation from your birth year, using Pew Research ranges, and your western zodiac sign.
Is this age calculator private?
Yes. Birth dates are worked out in this tab and are never sent anywhere.
Processing
All the date maths runs in your browser. The birthdays you type never reach a server, ours or any.
Storage
Dates are held only while the page is open. Refresh or close it and both boxes start empty again.
Account
No sign-up and no email. Check as many ages as you like for family, pupils or a whole class list.
Questions about calculating age
How many days old am I?
Enter your birthday and read Days under Total. It counts every day since you were born, with each leap day included.
How do you calculate chronological age?
Subtract the birth date from the test date, borrowing a month of real days when needed. Set Age on to the test date here.
How many days until my birthday?
The countdown under your age gives the days left, the date and the weekday. On the day itself it wishes you a happy birthday.
What day of the week was I born?
Enter your date of birth and the weekday shows with your age, worked out for any year back to 1 on today's calendar.
How do I calculate age in Excel?
With the birth date in A2, use =DATEDIF(A2,TODAY(),"Y") for years. "YM" gives the months left over and "MD" the days.
What if I was born on February 29?
In other years your age goes up on March 1, as in UK law. Switch it to February 28, the rule in New Zealand, if you need to.
What generation am I?
By Pew Research ranges: Gen Z 1997 to 2012, Millennials 1981 to 1996, Gen X 1965 to 1980, Boomers 1946 to 1964.
Still stuck, or found a problem? Email dobliquestudio@gmail.com and we will help.