Work out your percent
Enter your birthdate, and a lifespan if 80 years isn't the frame you want. Everything happens on this page.
How is the percent calculated?
It is one division. The top is the time from your birthdate to today; the bottom is the time from your birthdate to the same date after your chosen lifespan. The result is rounded to one decimal, so a 30th birthday on an 80-year frame reads 37.5%.
A few details keep it honest:
- Real calendar years. The span is measured date to date, so leap years are counted where they fall. A 29 February birthday lands on 28 February in years without one.
- Whole weeks. Weeks lived counts only full weeks since you were born, and weeks left counts full weeks until the end of the span — neither rounds up.
- Today, locally. "Today" is the start of today in your own time zone, so the number doesn't change with the hour.
What does a life in weeks look like?
The grid beside your result is the whole span, one row per year and 52 squares per row. Filled squares are weeks behind you, the darker square is the week you are in, and the empty ones are ahead.
An 80-year life is about 4,160 of those squares. The idea of drawing a life this way comes from Tim Urban's Your Life in Weeks: seen as a page of small boxes, a lifetime stops being an abstraction and becomes something you can count.
What lifespan should you use?
Any whole number from 1 to 120 years; it starts at 80. Treat it as a frame, not a forecast — the calculator does not estimate life expectancy, and the number it shows is only as meaningful as the span you give it. Some people like a round 80, others pick the age a grandparent reached. Either way, change it and the percent and the grid redraw together.
Why would anyone want to know this?
Not to feel worse. Most of us plan in days and years and lose the weeks in between — and the weeks are where a life is actually spent. Seeing them as a finite grid tends to do two useful things: it makes this week feel like one of a countable number, and it makes the question "what would I want this week to have held?" easier to answer.
How do you turn the number into a better week?
Keep it small. Pick the one or two things that would make this week one you are glad to have filled in, and give them a real slot in the calendar rather than a place on a list.
Is your birthdate private?
Yes. The calculation runs in your browser, and a refresh clears it. Decimal Life never receives the date:
- The birthdate is used on this device only and is not stored.
- A share link carries the percent, the lifespan and the week counts — never the date.
- The share card is drawn on your device; downloading it uploads nothing.
Key takeaways
- Your life percent is time lived divided by the span you choose, to one decimal — 37.5% at 30 on an 80-year frame.
- An 80-year life is about 4,160 weeks on the grid; the darker square is this one.
- The lifespan is a frame for thinking, not a prediction.
- Everything is calculated in your browser; your birthdate is never sent.
Frequently asked questions
How is the life percent calculated?
It is the time from your birthdate to today, divided by the time from your birthdate to the same date after your chosen lifespan — 80 years by default — rounded to one decimal.
How many weeks are in an 80-year life?
About 4,160 if you count 52 weeks a year, which is how the grid is drawn: one row per year, 52 squares per row. Counting real calendar weeks it is a little more, about 4,174.
Is my birthdate sent anywhere?
No. The calculation runs in your browser and a refresh clears it. A share link carries only the percent, the lifespan and the week counts — never the date — and the share card is drawn on your device.
What lifespan should I enter?
Any whole number of years from 1 to 120; it defaults to 80. It is a frame for thinking about your time, not a prediction — the calculator does not estimate life expectancy.
Sources
- Your Life in Weeks — Tim Urban, Wait But Why