Where "4,000 weeks" comes from
The phrase comes from Oliver Burkeman's 2021 book Four Thousand Weeks: Time Management for Mortals. Its premise is simple and a little startling: if you live to about 80, you get roughly four thousand weeks. Not four thousand years, not forty thousand: four thousand. The book argues that the goal of managing time shouldn't be to fit everything in, because you can't. It should be to choose, knowingly, what to leave out.
This page is a free calculator for that idea; it isn't affiliated with the book. If the number moves you, the book is well worth reading.
How it's calculated
4,000 weeks is 28,000 days, or about 76.7 years. We count the days since your birth, divide by seven, and round down. That's how many of the 4,000 you've used. The chart has 4,000 dots in rows of 50; the lit ones are yours so far, and the glowing one is this week. If you've already lived more than 4,000 weeks, congratulations: you're past the famous number, and every week from here is a bonus.
It's a round number, not an estimate of your life. Recent US life expectancy estimates (high 70s) happen to sit close to it, but averages don't describe any one person. If you'd like to plan with your own lifespan instead, try the life in weeks calculator, where you choose the total.
What to do with a finite number
Life is long if you know how to use it.Seneca
Burkeman's argument echoes Seneca's: the problem isn't the length, it's how we spend it. Knowing the total is finite is freeing, oddly. You will never clear your inbox, read every book or say yes to everything. So you can stop trying, and pick a few things to do fully.
A practical version: pick one thing to be your focus this week. Not five. One. Write it somewhere you'll see it. Next week, pick again. Four thousand weeks is plenty of time to do a lot of single things well, and almost no time at all to do everything at once.
Keep your weeks in view
That's the whole design of Days Unspent: a live desktop wallpaper with your weeks as a spiral, the days you have left to spend, and a single line for your current focus, with its deadline counting down. Your four thousand weeks on this page are free. The wallpaper is $29, once, for Mac and Windows.