Age & Date Difference Calculator
Enter a date of birth to get an exact age in years, months and days — or any two dates to see the span between them in weeks, days, hours and working days, with the next anniversary counted down.
The same span, every way
Next anniversary & working days
What Age Calculator does
Exact, not approximate
Years, months and days counted against the real calendar — not a division by 365.25 that drifts a day out every four years.
Leap years done properly
1900 was not a leap year and 2000 was. Both are handled, along with birthdays that fall on 29 February.
Working days
Count Monday to Friday between two dates and paste in your own public holidays to leave them out.
Any two dates
Past or future, in either order, with one click to swap them and one to jump back to today.
Next birthday
See the exact date, the day of the week it lands on, and how many days are left.
Nothing is uploaded
A date of birth is personal data. This tool never sends it anywhere — open your network tab and check.
How it works
Enter a date of birth or start date
Type it or use the date picker. The day of the week appears underneath.
Set the end date
It starts on today. Change it to any past or future date to measure a different span.
Read the breakdown
Exact years, months and days at the top; the same span as days, weeks, hours, minutes and seconds below.
Add holidays if you need working days
Paste one date per line to exclude them from the Monday-to-Friday count.
How people use it
Forms that ask for an exact age
Visa applications, insurance quotes and medical forms often want an age in years and months on a specific date, not just a birth year.
Notice periods and deadlines
Count the working days between today and a deadline, minus your own public holidays, to see how much time you really have.
Anniversaries and milestones
Find the day of the week you were born on, or how many days until a wedding, retirement or a child's next birthday.
Contracts and eligibility
Check whether someone had turned a given age on a given date — the boundary case where an off-by-one really matters.
Frequently asked questions
How is an exact age calculated?
Whole years are counted first, then whole months, then the days left over. So someone born on 15 June 1990, measured on 22 August 2026, is 36 years, 2 months and 7 days old — not 36.19 years. Dividing the day count by 365.25 gives an approximation that can be a day out; this counts the calendar itself.
What happens with a birthday on 29 February?
In a common year the anniversary is treated as 28 February, so someone born on 29 February 2000 turns 27 on 28 February 2027. Jurisdictions differ on this — a few use 1 March — so if it matters legally, check the rule that applies to you.
Are leap years handled correctly?
Yes, including the century rule that catches most calculators out: a year divisible by 100 is not a leap year unless it is also divisible by 400. So 1900 had no 29 February but 2000 did.
Does the working-day count include the start and end dates?
Yes. Monday to Friday of the same week counts as five working days, which is what you want when counting leave or a notice period. Weekends are excluded automatically, and any holidays you paste in are removed as well — holidays that already fall on a weekend are not deducted twice.
Can I count towards a date in the future?
Yes. Put the future date in either field. The order does not matter — the span is reported the same way, and the caption tells you which direction it read.
Does the time of day or my timezone affect the result?
No. Dates are handled as plain calendar dates with no time attached, so the answer is the same wherever you are. Only the Today button reads your device's clock, and it uses your local date rather than UTC.
Is my date of birth sent anywhere?
No. Everything is calculated in your browser with JavaScript, and the dates are deliberately kept out of the page address as well — a URL containing a date of birth would be sent to our analytics on any later visit and leaked in the referrer of any outward click. That means results are not shareable as a link, which is the trade we chose.
Last updated 2026-08-22