Once you decide the size of your book (or the trim size), the next step in self-publishing is to set your margins. This is the white frame that runs between the page’s text and the page’s edge.

To ensure that the words aren’t too close to the page edge where they could be cut off when the printer trims the paper, you want to ensue there’s enough white space. At the same time, the greater the white space, the more paper you’ll need for the book, potentially raising the printing cost.

Margins are measured in inches by their distance from the text to the page edge. Imagine a line running across the very top of your text. Place the edge of your ruler there then measure to the page edge, and you have your margin size.

Determining margins for your book first requires that you know your book’s trim size. Generally, for any book whose trim size is 6”x9” or smaller, use half-inch margins on all sides of the book except for the one nearest the binding. This is called the inside margin and needs to be slightly larger, usually three-quarters of an inch.

You want to have a larger inside margin because books curl near the spine. This means less light gets there, making words on that side of the page more difficult to read. A wider inside margin eliminates this issue.

Not all printers and book designers will agree with these simple rules. For example, mainstream publishing houses typically print books with top margins that are narrower than then the bottom margins. They also typically include a running footer, such as a page number, in the bottom margin. Many who self-publish, especially those formatting their books in Microsoft Word documents, place the page number in the top margin because doing so requires less fussing around. You’ll have decide which approach to take, but know that in self-publishing equal top and bottom margins are quite common.

Sometimes the “rules” for margins have little to do with the page edge. “The Chicago Manual of Style,” for example, recommends printing 65 to 70 characters (including spaces) on each line. This can be set if formatting Microsoft Word.

Some related terms you might run into when self-publishing include:
• Alignment – Text can be centered or the margins on the page’s right side either can be left ragged or so that the last letter of every line stops at the same spot (except at a paragraph’s end). The option you choose is the text’s alignment. If using Microsoft Word, opt for the “Justify” alignment, which is how this book’s right margin is printed (all letters end at a standard straight line).
• Justification – This either can refer to the alignment selected or to where your lines end at the bottom of the page. Regarding the latter, presuming the text fills the entire page, you want the last line of every page to end at exactly where the bottom margin begins. You wouldn’t want the text to end a half-inch from the page’s edge on an even-numbered page but then 4/7 of an inch from the page’s edge on the facing odd-numbered page, as this would look amateurish.
• Gutters – In larger books, you might split the text into two or even three columns. The white space between these columns is the gutter. Usually, the gutter is no more than a quarter-inch wide. When dividing books into columns, make sure each column is the same width. Also, if you have three columns that seem awfully thin, it’s always better to opt for two wide columns.