The other day, I opened yet another box of pens to replace one that had run dry. As often happens, this sparked a series of questions in my mind: How many boxes of pens do I go through in a year? How often do other people replace pens? But the third question lingered, catching my curiosity the most: How much ink do I actually use every year?
Since moving to Japan half a lifetime ago, I’ve settled on using A5-sized paper for nearly all my writing. It’s a convenient size—easy to carry, with a coverage rate that feels more efficient compared to A4. Almost every notepad and journal I use is A5. On a typical day, I fill about 25 pages with ideas, concepts, journal entries, programming notes, to-do lists, and the occasional flow or process review. Weekends often see a higher tally, while Mondays sometimes borrow pages left unfinished from the previous Friday. Each page usually holds between 220 to 300 words, depending on its purpose.
This led me to break out the calculator. Using some rough averages, here’s what the math looks like:
- 25 pages per day x 365 days = 9,125 pages per year
- 9,125 pages at an average of 250 words per page = 2,281,250 characters (not including arrows, lines, or sketches)
- 2,281,250 characters x 0.0005 mL of ink per character = 1.140625 litres of ink annually
Over a litre of ink! Of course, this number could be rounded down by about 10% to account for days when Ayumi and I are out exploring, but it’s still an incredible amount.
One litre of ink every year. Incredible.