One Space or Two?

Keyboard showing spacebar, in blog One Space or Two

How many spaces should follow the punctuation at the end of a sentence? One…two? And does anyone really care?

Since 1929, the American Psychological Association (the eponymous creators of the APA style) have had their say about how many end-of-sentence spaces we should be using, as set out in their style guide manual.

But in 2019, this particular academic publisher changed its guideline from using two spaces to using one space after a period (or full stop) at the end of a sentence, in line with most other manuals, such as the traditional The Chicago Manual of Style (Chicago style), the MLA Handbook from the Modern Language Association of America (MLA style), and The Associated Press Stylebook (AP style) – the latter being the most widely accepted style guide manual for business writing purposes, as well as journalists, of course, and freelance writers.

Having said that, the APA still request that draft manuscripts submitted to their journals are submitted with two spaces after a full stop. All those extra spaces will then be automatically stripped out in the typesetting process prior to publication in their journals. It seems that although the APA appreciate that two spaces at the end of a sentence make it easier for their reviewers and editors to read the drafts, the subscribers get to read the finished articles with one space.

This may annoy some authors drafting documents for submission to APA, because Microsoft has now weighed in and since 2020 their default position with Word is to flag two spaces as a grammatical error (although you can turn that notification off by tweaking your Word proofing options …at least for now).

Recent research

Some academics care enough about the one space–two space debate to conduct studies and publish journal articles on the subject.

Some research suggests that two space punctuation may facilitate reading, in particular how you process the gap between sentences. One paper (Johnson et al, 2018) that appeared in the journal Attention, Perception, & Psychophysics in 2018 suggests it might be something to do with the length of time you spend eyeing up the full stop that’s key. The paper suggests that initial processing of the text is made easier when two spaces follow the full stop.

How easy you find text to read, however, could just be a matter of what style you use yourself (as well as the difficulty of the subject matter, of course). The journal article mentioned above notes that the two-space typists in their study group found that two-space punctuated sentences made the overall text easier to read. Similarly, one-space typists favoured the one-space punctuated sentences.

Eye movement tracking used in the same study suggests that two spaces may make processing of sentences easier because people spend less time fixated on the punctuation region and gap than they do with one space at the end of sentences.

As I interpret that last point, it may be that spending less time being distracted by not clearly seeing the end point of a sentence could, in effect, keep you focused on the text. So does making the separation between sentences visually more obvious make reading more efficient? And maybe older people and those with visual impairments prefer two spaces.

Short and gappy

Digressing for a while, many of us will know from personal experience that shorter sentences often make it easier to understand what we are reading. I am constantly reminded by a WordPress plug-in as I write posts what the Flesch Reading Score for my post is and what percentage of my sentences contain more than 20 words (being the maximum I should stick to, but rarely do).

The style guide prepared by The British Psychological Society (BPS) states that “…for the purpose of aiding comprehension, shorter sentences, and therefore more full stops, are better than peppering text with commas and semicolons”.

The BPS also recommends “to aim for the shortest sentences that sense and tone will allow”. This reminded me of something I experienced in a Geophysics class I attended some years ago. I recall how one student’s report was discussed. We were told that this report had received extra marks for using short sentences and paragraphs, both of which had made it easier for the tutor to read. Most of the rest of the class hadn’t done this.

My opinion back then was that the student’s report style had over-simplified the content by the plethora of brief sentences and paragraphs. The reading flow felt blocky and the report had the feel more of a step-by-step guide than a review, much like a set of bullet points. I also recall the student was dyslexic and believe that the report had been written for his own ease of reading, rather than for consumption by others. But I’m not the tutor, so my two pennies’ worth counts for nothing. However, I do believe that there is a fine line that can be inadvertently crossed when attempting to make paragraphs and sentences short for ease of reading.

In terms of spaces after short sentences, I suppose that a piece of text made up of lots of short sentences, each finished off with two spaces, would effectively make the text look distractedly gappy, so there is probably an advantage to using one space if you are inclined to use short sentences.

Two spaces after a period. One space  after a period. Line break after every sentence. One space or two.


Some readers may not have given spacing after the end of sentences any thought whatsoever and may not have even noticed any difference between the publications they read. You may be a two-space typist or a one-space typist and prefer one or other style. However, some of you, like me, may pine for the missing space after the full stop. I have written this post using one space at the end of sentences, as I’m required to do, despite many pre-digital years of doing otherwise. Initially, I disliked using one space.

In a typing course decades ago, I was taught to use two spaces after punctuation at the end of a sentence, two spaces after a colon, and one space after everything else. It has always been a chore to remember to drop the extra space when typing posts and laying out articles in InDesign. Then I go and carry out some part-time work for a previous employer who insists that all of the work is typed with two spaces after the full stop.

So imagine my shock the other day when I was typing a legal-type document and realised that I had crossed over to the dark side. Three pages in and I realised I had typed everything up to that point with one space after all the full stops without being aware I was even doing it. I was horrified and elated in equal measure.

It is extremely useful that I no longer have to force myself to leave only one space. But what about when I have to produce work “old style”? I could just use a search and replace function, but I prefer to get it right as I go along. In that recent job, as I typed on, I realised it didn’t take long to revert to the old two-space style, so I now class myself as bi-spatial.

If you liked this article, you might also like my articles To Whom It May Concern and Me, Myself and I.