How many days since my birthday?
Enter your date of birth to see how many days since your last birthday, how many until the next one, and your total days lived.
Two numbers get asked for here: days since the most recent birthday, and days lived in total. Both come from the same date.
Days since your last birthday
This resets to zero every year on your birthday and climbs back to 365 or 366. Halfway is day 182 or 183, which is the half-birthday some people mark. The counter shows the figure alongside the days remaining until the next one, so the two always add up to the length of your birthday year.
Days lived in total
The lifetime figure is the one with the interesting milestones. Day 10,000 arrives shortly after the twenty-seventh birthday, day 20,000 at around fifty-four, and day 30,000 at around eighty-two. None of them fall near a birthday, which is what makes them worth knowing.
Why the total is not simply age times 365
Leap years add a day roughly every four years, so by age forty the simple multiplication is about ten days short. The counter works through the actual calendar instead, which is why it can give the weekday of your birth as well as the total.
How the counting works
The total is a count of complete days, not a rounded figure. It increases at midnight in your own timezone rather than in UTC, which is what the dated pages elsewhere on this site use, and every leap day in the period is included, which is why the number can differ by a few days from multiplying years by 365. Weeks are the day total divided by seven, and months use the average calendar month of 30.44 days, so the month figure is an approximation while the day figure is exact.
Nothing you type is transmitted or stored. The date stays in your browser, the arithmetic runs there, and reloading the page clears it.
Questions
- How many days since my birthday this year?
- Enter your date of birth above and the counter gives the exact figure, along with the days until your next one.
- How many days old am I?
- The counter shows the lifetime total. For more detail there is a full age calculator.
- What if my birthday is 29 February?
- The counter uses the real calendar, so it handles leap-day birthdays without rounding.