Why 80 years
Eighty years sits close to the average American life. Under the Social Security Administration's 2023 period table, life expectancy at birth is about 76 years for males and 81 for females, and someone who has already reached 40 can expect to live to around 79 to 83 on average. An 80-row calendar therefore feels honest without being grim.
With ten fewer rows than the 90-year version, each box prints a little larger on the same sheet of paper, which makes the calendar easier to fill by hand.
Using it
Shade one box per week lived. Row 0 is your first year of life; the number on the left is your age during that row. When you reach the bottom you have not run out of anything; you have simply outlived the page, and you can tape a 90- or 100-year sheet underneath.
If you are planning around a specific horizon, such as working until 65 or the years until a child leaves home, draw a line across the row where that horizon falls. The boxes between today and the line are the time you actually have to work with.
Printing
Prints on one page. Choose tabloid if you want the poster for a wall and letter for a notebook or a binder. Use 'Save as PDF' to send it to a print shop.