For decades, folks here in the United States have been using double spacing after periods, because — or so they think — that’s what you’re supposed to do. It’s true, there are rogue English teachers across America who may require you to do so, however, authorities on style and formatting universally tend to agree that two spaces following a period is unnecessary, and, in some cases, can be distracting and just plain wrong.
Double Spacing: Monospace vs. Proportional Typesetting
A recognized authority on style and formatting in formal publications, the Chicago Manual of Style, indicates that there is no reason for double spacing after periods in published works. The tradition in modern US publications comes from the use of typewriters prior to the dawn of the personal computer and modern font and typesettings. The problem with typewriters was that they used monospaced typesetting, meaning that every character takes up an equal amount of space, in opposition to proportional typesetting, in which marginal letters and characters were given less space than wider ones.
Monospaced types create text that looks “loose” and uneven with a lot of white space between characters and words, so it’s more difficult to spot the spaces between sentences immediately. Business Insider states that this caused the adoption of the two-space rule on typewriters: an extra space after a sentence makes text easier to read (However, the folks over at CreativePro disagree. They indicate that double spacing after a period has been a long historical precedent that found a practical use with the monospaced fonts used on typewriters).
So, what does this mean for you and your resume? Don’t put two spaces after a period. It actually can make text more difficult to read because we are conditioned to pause when there is an extended space, which disrupts the mental flow of the text. Specifically on a resume, you should not use double spacing following a period because:
Real Estate
Real estate, meaning the physical space on the paper, is valuable on a resume — you want to cram as much information, in a palatable manner, on the page as you can. As silly as it may seem, a few extra spaces can lead to an extra line or two on the page, and that affects the aesthetics of your resume. Beyond that, as stated above, the white space can make your resume more difficult to read anyway, and you do not want distractions on your resume.
Aesthetics
Secondly, it is generally accepted by most professionals that double spacing is old-fashioned. Yes, some believe it is professional, but very, very few will find you to be unprofessional by failing to double-space. Most of the “old guard” who believe double spacing following a period is crucial, also recognize that this is no longer a common practice, and while those few may like you for double spacing, chances are they will not discount you for not double spacing. The vast majority of us look at double-spacing following periods and think, “huh, doesn’t he know not to do that? It’s not 1952 anymore.” James Felici, from CreativePro says it well: “Modern spacing aesthetics aside, the main reason not to use two word spaces (or an em space) between sentences is that people will think you’re doing it out of ignorance. It will be perceived as a mistake. You may know better, but you’ll have a hard time convincing everyone else.”