Line Length: Why Full-Width Text Is Hard to Read

There’s a category of design mistake that persists not because it’s hard to fix but because nobody notices it’s a mistake. Line length is my favorite example. On a large monitor, plenty of sites let paragraphs run edge to edge, two hundred characters or more per line. The fix is a single CSS declaration, something like a max-width of 65 characters on the text column. Almost nobody applies it, because almost nobody realizes anything is wrong.

To see why it’s wrong, you have to think about what reading physically is. Your eyes don’t glide smoothly along a line of text. They jump, land, jump again, taking in a few words at each landing. At the end of a line comes the hardest move: a long leftward sweep back to the start of the next line. That return sweep is where reading breaks. The longer the line, the longer the sweep, and the easier it is to land on the wrong line, either re-reading the one you just finished or skipping one entirely. You’ve felt this. You get to the left margin of a wide page and there’s a flicker of hesitation, a moment of searching. That flicker, repeated every line for an entire article, is the tax that long lines charge.

Typographers converged on an answer to this long before screens existed. Somewhere around 45 to 75 characters per line, including spaces, reading feels effortless. Books cluster in that range. Newspapers cut their pages into narrow columns for the same reason. This wasn’t aesthetic fashion. It was centuries of people whose livelihood depended on being read, discovering by trial what eyes can comfortably do.

Then the web arrived with a default that ignores all of it. HTML text fills its container, and the container defaults to the window. On the small monitors of the nineties this was accidentally fine, because the window itself enforced a reasonable measure. As screens grew, the same markup quietly became unreadable. The page didn’t change. The world under it did. This is worth pausing on, because it’s a general pattern: defaults that were harmless in one era become harmful in another, and nobody sends a notification.

Phones created the opposite illusion of safety. On a phone, the screen is narrow, so line length mostly takes care of itself, and a founder who checks the site on their phone sees nothing wrong. But the same person’s customers open that site on a laptop, often a wide one, often with the window maximized. The desktop view is where proposals get read, where procurement people evaluate you, where anyone doing serious comparison shopping ends up. That’s exactly the audience getting the 200-character lines.

What makes long lines insidious is that readers don’t diagnose them. Nobody thinks, this line measure exceeds my saccadic comfort. They think, this is a wall of text, and they stop reading. The discomfort is real but anonymous, so it gets attributed to the writing, or to their own attention span, or to nothing at all. The site owner sees people bouncing off long pages and concludes the content is too long, so they cut it. The content was fine. The container was broken.

I check for this constantly when GazeSite takes desktop screenshots of sites, and it shows up on serious, well-funded sites more often than you’d expect, especially on the pages built from templates meant for hero images rather than paragraphs: the about page, the documentation, the terms, the blog. The homepage gets a designer’s attention and a constrained column. The pages made of actual sentences get whatever the container does by default.

There’s a legitimate question hiding here: if narrow columns are better, why not make them very narrow? Because too short is also bad. When lines hold only three or four words, the return sweep happens constantly and the rhythm of reading gets choppy, like driving in first gear. You mostly see this in over-eager multi-column layouts or in text squeezed beside an image. The comfortable range is a band, not a direction.

The practical advice fits in one sentence: give every block of body text a maximum width of roughly 60 to 70 characters, center the column or place it deliberately, and let the empty space on either side just be empty. That last part is what stops people. Wide margins feel like waste, and filling available space feels like diligence. But the space wasn’t yours to fill. It exists so the text can be read. A page with a narrow, comfortable column and generous margins isn’t underusing the screen. It’s using the screen for exactly what the reader came for, and nothing else.