Why single spaces after full-stops rule

This one isn’t a debate. I’m dealing with cold, hard facts. You can disagree if you want to. but you’ll be wrong.

I’m talking about the period-followed-by-spaces rule. And I’m here to tell you something you might not like: typing two spaces after a full-stop (or period if you prefer) is wrong. It couldn’t be more wrong if it was named W. H. Wongy McWronginstien of Wrongsville, Tennessee. Population: Wrong.

Seriously though, this is hotly-contested even among non-writers. People who just send emails for a living. But, and I’m speaking for the editors of the world here, please stop doing two spaces. It causes them all sorts of trouble.

Now what do I know about this? Nothing. But James Felici, author of The Complete Manual of Typography knows a lot about it. It was decided an absolute age ago by professional typographers that you need just one single space between sentences after a period. Period. Why? Well because typesetting already allocates a little extra space after a full-stop. Not quite two spaces worth, just a little over one space. They’re already doing that part of the job for you. A typesetter or editor working through your manuscript has to fix it if you’ve written two spaces, before it can get to the print-ready stage. Okay, this is a simple search-and-replace job, but it’s a niggle that they really don’t like. And you should always try and keep your editor happy.

So where do the “two-spaces” thing come from, if one space has been the rule for decades? Typewriters.

Yes, typesetters had been making spaces slightly wider after full-stops for decades before the typewriter came along. But most typewriters use monospaced fonts. I’ve noted before that I actually like typing my novel drafts in Menlo, a monospaced font. But the problem with typewriters is that the space after a period is of course, just as short as a regular space. So typists being training on the “new fancy” typewriters were told to do two spaces. And annoyingly – particularly with older generations – the practice has stuck. And often it gets passed down.

But we live well into the twenty-first century now. Desktop publishing and proportionally-spaced fonts are the standard, and have been for decades. We just don’t need to do the double-space thing any more.