Each day is 1" x 1.5". Even though the square is small I can make two or three notations in each square.
The pen is not included in the package. So I tried a couple of pen I had at home. I started writing on it with a permanent ink pen and that ink cannot be erased. However, I found another non-permanent ink pen (black in the video) that can be erased by using a paper towel.
The calendar is shipped rolled so it took a little work to make it lay flat. I am using scotch tape to attach it to the wall of my office.
This calendar is available on Amazon by following this link.
Ali Julia review ★★★★☆