Age Calculator
Work out an exact age in years, months and days from a date of birth, plus total days, weeks and hours, and a countdown to the next birthday.
Age
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Enter a date of birth to see the answer.
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All Calculators tools →This tool runs entirely in your browser. Nothing you enter is sent to our servers, so there is nothing for us to store or see.
About the Age Calculator
Enter a date of birth and get an exact age: years, months and days, counted the way a calendar counts rather than by dividing days by 365.25. You can measure to today or to any other date, which is what you need for a form asking "age at the time of the event".
The month arithmetic is the part that goes wrong in most age calculators. From 31 January to 1 March is one month and one day, because adding a month to 31 January gives the end of February. Naive implementations subtract 31 from 28 and produce a negative number of days, or silently roll over into March and lose a day. This one counts whole months first, clamps the monthly anniversary to a real date, then counts the remainder.
Alongside the age you get the total in days, weeks, months, hours and minutes, the day of the week you were born, and a countdown to your next birthday. A 29 February birthday is handled explicitly: in a common year the anniversary is shown as 1 March, which is the English legal convention, and the tool says that is what it did rather than moving the date quietly.
How to use the Age Calculator
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Enter the date of birth
Use the date picker, or type it as YYYY-MM-DD. An impossible date such as 30 February is rejected with the real number of days in that month.
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Choose the date to measure to
It starts on today. Change it to work out an age at a particular moment — on the day of an exam, a policy start date or a historical event.
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Read the exact age
Years, months and days appear together, with the totals in days, weeks, hours and minutes underneath.
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Check the birthday countdown
The panel shows the date of the next birthday, how many days away it is, and which age it will be.
Frequently asked questions
Why does another calculator give me a different number of days in the month?
Because month lengths vary and there is more than one defensible way to handle it. This tool counts whole months from the birth date, clamping the anniversary to a real day — so 31 January plus one month is 28 or 29 February — then counts the days after that. Tools that subtract day numbers directly produce negative values on month-end dates and quietly patch them.
How is a 29 February birthday handled?
The birthday exists only in leap years, so in the other three the anniversary is shown as 1 March. That is the English legal convention; Scots law uses 28 February, and both are used informally. The result says which convention is being applied rather than moving the date without telling you.
Is the age calculated in my time zone?
A date of birth has no time zone, so none is applied. The calculation works on the three numbers you enter, which means it produces the same answer everywhere. The only place the clock is read is to fill in today's date, and that uses your local one.
Can I use it to find the gap between two dates that are not birthdays?
Yes, and it works exactly the same way — the earlier date goes in the first field. If you want weekday counts or a breakdown in weeks rather than an age, the Date Difference calculator is a better fit for that shape of question.
Is my date of birth sent anywhere?
No. The calculation runs entirely in your browser and nothing is transmitted or stored. A date of birth is personal data in most jurisdictions, which is a good reason for a tool like this not to have a server at all.