https://www.google.com/search?q=page%20width%20study#q=optimal+page+width+for+reading&safe=off
The first link say 100 characters per line. If 100 characters equal to page width, then page width is the optimal line length.
https://www.google.com/search?q=page%20width%20study#q=optimal+page+width+for+reading&safe=off
The first link say 100 characters per line. If 100 characters equal to page width, then page width is the optimal line length.