Since the advent of computers and word processing software, one space goes after period, not two.
Why? The simplest explanation is that in typesetting, software makes room for a wide font such as W.
One space has been the norm since mid 20th Century. “The Complete Manual on Typography (2003) states that “The typewriter tradition of separating sentences with two word spaces after a period has no place in typesetting” and the single space is “standard typographic practice.”
In Microsoft software, use the Find&Replace command.
- Press Ctrl+H.
- In the Find what box, type a period and hit the spacebar twice.
- In the Replace with box, type a period, and hit the spacebar once.
- Click Replace All.
The software will find all instances of where you added two spaces after a period and replace them with a period with one space after. Fixed before you can blink.
When I was in publishing and had to fix documents from other people, I recorded a macro and created a shortcut and a toolbar button that made it even quicker.
Break the Habit
To break the habit of adding two spaces after the period, every time you do two spaces, stop right then. Delete that last word (or more) and try again, focusing on doing one space. It’ll soon become the norm for you.