Age Calculator
An age calculator that counts whole calendar months, so it answers 34 years, 2 months, 5 days, then repeats the same span in months, weeks and days.
Exact age
Choose a date of birth to begin.
This year of your life
How to use
- Set Date of birth. The Exact age figure fills in as soon as the field holds a complete date.
- Age at the date has already put today in for you, so for the plain how-old-am-I question you can stop here.
- Asking about some other day? Put that day in the second box. It refuses anything later than today.
- Read the top figure as three separate counts: whole years, then the whole months left over, then the days left over.
- Total months, Total weeks and Total days are for forms that want one unit rather than three.
- Days to next birthday reads 0 on the day itself and starts counting down again from the day after. The bar under the cards shows the same year as days gone against days to go.
- Both dates are written into the address as dob and asof, so copy the URL if you will want this figure again.
About this tool
Pick a date of birth and the answer is on screen before you reach for anything else. There is no Calculate button on this age calculator, because two date boxes are the whole of the input. The answer reads back something like 34 years, 2 months and 5 days, leaving out any unit that comes to zero, and four cards under it give the same stretch of time as Total months, Total weeks, Total days and Days to next birthday.
The second box is the one people miss. Age at the date fills itself in with today, and moving it backwards answers a different question: how old was someone on the day of the exam, or on the day a policy was written? It will not go forward past today. The arithmetic walks one calendar month at a time and compares both dates in UTC, which is why a 29 February birthday and a daylight-saving change both land correctly.
Where it stops
- Calendar arithmetic is the whole job here. Whether a 29 February birthday counts as the 28th or the 1st for a legal age limit is a question for local law, and the law does not always agree with the count on this page.
- Gregorian dates only. A Hijri or Hebrew date has to be converted before it goes in the box.
- Total weeks is rounded down, so up to six days of the current week are not shown there. The birthday countdown moves in whole days too, and it turns over at midnight by your device's clock.
Frequently asked questions
Why does it say 2 months and 5 days instead of just giving me a number of days?
Because that is how people say an age out loud. The count steps forward one calendar month at a time and only banks a month once the same day number comes round again, which stops a 31-day month and a 28-day month from being treated as equal. The flat figure is still there in the Total days card.
I was born on 29 February. What does it do in an ordinary year?
It treats 28 February as your birthday in any year without a 29th, so your age goes up once a year like everyone else's and the countdown never sits waiting for four years. Some places settle on 1 March instead for legal purposes, which is a rule about law rather than about counting.
Can I work out how old someone was on a particular day in the past?
That is what the second box is for. Birth date in the first, the day you care about in the second, and every card answers for that day. The same calculation covers someone who has died, which is where the age-at-death question usually comes from.
Does travelling or daylight saving shift the number by a day?
No. Both dates are pinned to UTC midnight before anything is compared, so the result depends on the two squares you picked off the calendar and not on the clock your laptop is keeping.
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