I can fit mm paperbacks two rows high and two rows deep, though!gertiekindle said:I like the trade paperbacks better. Bookshelves are set up to accommodate the height of hardbacks. The mass market paperbacks are so short they leave about six inches between the top of the book and he next shelf up. The trades are taller and thinner, so they take up more of that wasted space. Since they are thinner than the mm pb, I can fit more on a shelf. I also noticed that consignment stores won't take mm; they only take trades.