Birthday Calculator
Count down to your next birthday, see which day of the week you were born on, and how many days, weeks and hours you have been alive.
How to use it
- Pick your date of birth from the date field.
- The countdown to your next birthday updates automatically.
- Everything is worked out from your device's own clock and timezone.
Examples
| 15 June 1995 | Born on a Thursday |
Enter a date of birth and this works out the day of the week it fell on, a live countdown to the next birthday, and a running total of exact days, weeks and hours lived — figures that are all a little more fiddly to get right by hand than they look, because of leap years and how many days sit in each month between now and the birthday.
Worked example
Someone born 15 June 1995 was born on a Thursday. As of today, 23 August 2026, they've been alive for over 31 years, and the countdown shows how many days remain until 15 June 2027 — recalculated automatically from the device's own clock, so it's always current without needing to reopen the page on the day itself.
The leap year edge case
A birthday on 29 February technically doesn't exist in three years out of four. In non-leap years the countdown rolls the observed date to 1 March, which matches how most people informally celebrate it, though some jurisdictions and contracts legally treat a 'leapling's' birthday as 28 February instead — worth checking if the date has any legal significance.
Questions people ask
What happens if I was born on 29 February?
In non-leap years the browser rolls the date to 1 March, so the countdown lands on the day after the leap date. Common-law practice varies, so treat it as an approximation.
Is anything sent to a server?
No. Every calculation runs in your browser, so nothing you type is uploaded and the page keeps working offline once it has loaded.
Last updated 17 August 2026