Page mar­gins set the de­fault ter­ri­tory your text oc­cu­pies on the page. Be­cause they de­ter­mine the max­i­mum width of the text block, page mar­gins have the great­est ef­fect on line length. (Point size also af­fects line length, though more finely.) As page mar­gins in­crease, line length de­creases, and vice versa.

Most word proces­sors de­fault to page mar­gins of one inch. On stan­dard 8.5″ × 11″ pa­per, that pro­duces a line length of 6.5″. That was fine for the mono­spaced fonts of the type­writer era, which used a lot of hor­i­zon­tal space. But for pro­por­tional fonts, they’re too small.

At 12 point, left and right page mar­gins of 1.5–2.0″ will usu­ally give you a com­fort­able line length. But don’t take that range as an ab­solute—fo­cus on get­ting the num­ber of char­ac­ters per line into the right range (see line length). The smaller the point size, the larger the page mar­gins will need to be, and vice versa.

“But if I use big­ger mar­gins, won’t a lot of the page be empty?” Sure. Is that a problem?

The 8.5″ × 11″ pa­per size is a stan­dard im­posed on us by his­tory and tra­di­tion. It does not rep­re­sent any­one’s idea of a con­ve­nient size for good ty­pog­ra­phy. 

Here’s the proof. Are there any pub­li­ca­tions that use 8.5″ × 11″ pa­per? Yes, it’s the ap­prox­i­mate size of many mag­a­zines. But do any of those mag­a­zines run text in a sin­gle block on the page with one-inch mar­gins? No, never. They use mul­ti­ple-col­umn lay­outs or find other ways to di­vide the page.

So are there any pub­li­ca­tions that do run text in a sin­gle block on the page? Sure—books are usu­ally set in a sin­gle col­umn. But do you ever see a book printed on 8.5″ × 11″ pa­per? No, never. It would be too big for com­fort­able reading.

Pro­fes­sional ty­pog­ra­phers never use 8.5″ × 11″ pa­per with a 6.5″ line length. Nei­ther should you. Set your text ac­cord­ing to the prin­ci­ples of good ty­pog­ra­phy. The white space will take care of it­self. The plea­sure of read­ing an ef­fec­tively de­signed doc­u­ment will soon out­weigh the un­fa­mil­iar­ity of ex­tra white space around the edges.

“But with those big mar­gins, I won’t get nearly as many words on the page.” Oh really? Let’s ad­dress that fear with a word-proces­sor ex­er­cise that brings to­gether some of what you’ve learned so far.

1. Start a new doc­u­ment in your word proces­sor. Paste in a text of at least 1000 words.

2. For­mat this new doc­u­ment as fol­lows: page mar­gins of 1″ per side, font is Times New Ro­man, point size is 12, line spac­ing is “Dou­ble” (if you’re us­ing Word; if not, use ex­actly 28 points), first-line in­dent is 0.5″, and no space be­tween para­graphs. I’ll call this doc­u­ment A.

3. Start an­other new doc­u­ment in your word proces­sor. Paste in the same text.

4. For­mat this sec­ond doc­u­ment as fol­lows: page mar­gins of 2″ per side, font is still Times New Ro­man, point size is 11, line spac­ing is ex­actly 15 points, first-line in­dent is still 0.5″, and still no space be­tween para­graphs. I’ll call this doc­u­ment B.

5. Print both doc­u­ments. Which one looks more like a pro­fes­sion­ally type­set book: A or B?

6. Which doc­u­ment is more com­fort­able to read: A or B?

7. Which doc­u­ment con­tains more words per page: A or B? Hint: use word count. See line length for instructions.

I’m guess­ing you an­swered B to the last three ques­tions. If so, you’re see­ing how good ty­pog­ra­phy can be a benev­o­lent force—it im­proves the ap­pear­ance and leg­i­bil­ity of your text with no com­pro­mise in words per page.