Your age, counted in days
Years are a blunt unit. "I'm 32" covers everything from the morning of your birthday to the night before the next one. Days are honest: every one is a single sunrise you actually saw. Counting your life in days turns a birthday number into something closer to a running total, and it tends to make people curious in a good way. You've had more than ten thousand of these already? What happened to most of them?
How it's calculated
We count the calendar days from your date of birth to today, in your local time zone. Leap days are counted, because you lived them. Weeks are the days divided by seven, rounded down. Months and hours are shown as approximations (an average month is about 30.44 days), so they carry a "≈". Nothing you type is sent anywhere: it's arithmetic in your browser.
The 10,000-day milestone
Turning 10,000 days old happens at about 27.4 years: 27 years and between 4 and 5 months, depending on leap years. It has become a small tradition for some people to mark it with a "10,000 days" party, a trip, or a letter to themselves. The next round markers are 15,000 days (about 41), 20,000 (about 54 years and 9 months) and 25,000 (about 68). The calculator gives you the exact date of your next one, so you can put it in your calendar now rather than notice it afterwards.
Milestones like these work because they're arbitrary. They aren't tied to school years or tax years or anyone else's schedule, so they make a clean, personal place to stop and look around. Psychologists call this the fresh-start effect: people are more likely to begin something new at a landmark in time, and a day-count milestone is a landmark nobody else is using.
Days spent, days unspent
Begin at once to live, and count each separate day as a separate life.Seneca
Seneca's advice is the best use of this number. Not to tally up a past you can't change, but to notice that each day is its own whole unit. You don't have to fix your life this year. You only have to spend today well, then do it again tomorrow.
The other half of the count is the days still ahead of you. If you'd like to see that number too, try the days left calculator, or see the whole picture at once on the life in weeks chart.
Keep the count in view
Days Unspent is a live desktop wallpaper for Mac and Windows that shows the days you have left to spend, ticking every second, with your weeks drawn as a spiral and the one thing you're working on right now. The number on this page is free forever. If you'd like it behind your work every day, it's $29, once.