Four feet three inches.
1. Take the 20-word "five musts" as an example.
First, fold five lines vertically, but the fifth line is half a line, with left and right margins (that is, leave appropriate blanks); Fold it horizontally into six equal parts (the upper and lower edges should also be left, that is, the "heaven and earth" should be left with appropriate blanks). The first to third lines are 6 words each, the fourth line is 2 words, and the fifth line is signed.
2. Take the 28-character "seven musts" as an example.
First, fold five lines vertically, but the fifth line is half a line, with left and right margins (that is, leave appropriate blanks); Divide into seven equal parts (the upper and lower edges should also be left, that is, the "heaven and earth" should be left with appropriate blanks). The first to fourth lines are 7 words each, and the fifth line is signed.
3. Take the 33-word "long and short sentences" as an example.
Fold vertically into five equal parts first, but leave the left and right edges (that is, leave appropriate blanks); Fold in half horizontally and divide it into eight equal parts (the upper and lower edges should also be left, that is, the "heaven and earth" should be left with appropriate blanks). The first to fourth lines are 8 words each, the fifth line is 1 word, and the next space is signed.