Thursday, May 7, 2020 [Tweets] [Favorites]

Microsoft Word Now Flags Double Spaces As Errors

Tom Warren (Hacker News):

Microsoft has settled the great space debate, and sided with everyone who believes one space after a period is correct, not two. The software giant has started to update Microsoft Word to highlight two spaces after a period (a full stop for you Brits) as an error, and to offer a correction to one space. Microsoft recently started testing this change with the desktop version of Word, offering suggestions through the Editor capabilities of the app.

Much of the debate around one space or two has been fueled by the halcyon days of the typewriter. Typewriters used monospaced fonts to allocate the same amount of horizontal spacing to every character. Narrow characters like “i” got the same amount of space as “m,” so the extra space after the “.” was needed to make it more apparent that sentences had ended. Word and many other similar apps make fonts proportional, so two spaces is no longer necessary.

I’ve never understood the explanation that the recommendation has changed because of proportional fonts. Why would the widths of the letters matter? A space is still a space. It’s not as if the font knows to make sentence-ending spaces wider. If anything, there is by default more perceived space with a typewriter because the period character is wider, yet mostly empty, so the last letter of one sentence and the first letter of the next are farther apart.

As far as I can tell, what changed is the preference of designers for how much space there should be.


Historical style guides before the 20th century typically indicated that wider spaces were to be used between sentences. Standard word spaces were about one-third of an em space, but sentences were to be divided by a full em-space. With the arrival of the typewriter in the late 19th century, style guides for writers began diverging from printer’s manuals, indicating that writers should double-space between sentences. This held for most of the 20th century until the computer began replacing the typewriter as the primary means of creating text. In the 1990s, style guides reverted to recommending a single-space between sentences. However, instead of a slightly larger sentence space, style guides simply indicated a standard word space. This is now the convention for publishers.

John Gruber:

Go look at a few professionally-typeset books — every single sentence on every page in every book has one space after the period.

I have shelves full of books typeset with LaTeX, which by default puts more than a single space at the end of each sentence. It think this looks much better. But, crucially, LaTeX only makes the space fractionally larger. There’s no easy way to do that with most software, and if it’s a choice between one and two spaces, I think two looks odd.

Single spaces introduce a technical problem, which is that the software can’t tell whether a period is at the end of a sentence or merely following an abbreviation. LaTeX’s solution is that you have to manually mark periods that are not sentence ending. People often forget to do this. It also treats runs of multiple spaces as a single space, like Web browsers do.

Daniel Kehoe:

I was active on the www-talk mailing list in 1993. In July, in the thread “Space after Periods,” Terry Allen (an editor at O’Reilly) wanted rendered HTML documents to follow Tex conventions with extra space after a period.


Terry Allen and I engaged in some snarky backbiting, then Ken Chang of NCSA Publications said he preferred “‘one space fits all’ as writers of HTML really shouldn’t need to know the fineries of typography.” Marc Andreessen (still at NCSA in 1993) pointed out browser developers couldn’t be expected to implement the syntactic analysis required to distinguish the end of sentences from inter-sentence periods. Finally Guido van Rossum (the developer of the Python programming language) complained that, “extra space after a sentence… is mostly propaganda by Knuth and Kernighan (TeX and troff)” and implored, “Let’s keep HTML simple!” You may know that Python is unique among programming languages in treating whitespace as significant. At the time, I hadn’t yet learned to use Python (it was still pre 1.0) and didn’t know that Guido van Rossum had strong feelings about the significance of whitespace.

In the end, we ended up with browsers putting a single uniform space between sentences (as you can see on this page).

Martin Wierschin:

I recently came across a copy of the COVID-19 economic relief explanation letter being sent out by the White House here in the United States[…] What was interesting to me was not the contents of this letter, but rather the spacing after each period.

Update (2020-05-14): Simone Manganelli:

Another reason to prefer more than one space after a period: it is FAR easier to scan long pieces of text and understand some of it, because my eyes can more easily pick out the beginning and ends of sentences.

This is literally the same reason why we have paragraphs.


The (sadly, now defunct) blog, Heraclitean River (archived at the Wayback machine: has a wonderful article and a followup article on this subject. It should be required reading for anybody who thinks they want to take a side on the one-or-two-spaces-between-sentences war.

Why two spaces after a period isn’t wrong (or, the lies typographers tell about history):

The Chicago Manual of Style and a single space after periods:

Well into the 2000s I double spaced after an ending period, but I changed to be more compatible with most other people I knew. As such, neither way bugs me. People are silly to argue about it.

Sören Nils Kuklau

crucially, LaTeX only makes the space fractionally larger.

Makes sense to me. Two full spaces never looked right to me, but the argument that there should be slightly more space than between words rings true to me.

Given that Word has heuristics to detect new sentences (vs. new words) anyway, I do feel like LaTeX’s 1.33em spacing should be the default, rather than 1.

For HTML or Markdown, it’s a harder sell. The burden of handling/suggesting this to the user would likely have to be on the side of CMSes, not browsers.

Well into the 2000s I double spaced after an ending period, but I changed to be more compatible with most other people I knew. As such, neither way bugs me. People are silly to argue about it.

Seems to me someone ought to conduct a study as to which extreme is more readable, to settle this debate.

A period or full stop character at the end of a sentence, and a capital letter at the beginning of the next sentence seem to be enough to separate sentences. Never have I had an issue separating sentences in a text. Adding an extra space would only make sense if either there was no period or no capital letter available. Double space is definitely overkill. If not, why not three or four spaces? Or better yet, why not make a new paragraphe for each sentence?
Single space it is.

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