If I write a document that I have to hand in to somebody (a report, summary, draft, whatever) I usually justify the text because it seems more appealing (at least to me) if it all finishes at the same length. However, now I read that it may be more difficult to read overall because lines do not seem so unique and the reader's eye may be misguided.

How do you usually hand in documents? Any advice or even scientific studies about that?

4 Answers 4


Stiff, P. (1996). The end of the line: a survey of unjustified typography. Information Design Journal, 8(2), 125–152.

No empirical data, but a good overview. Science would tell us that inconsistent word-spacing as a result of justification may inhibit saccadic eye movement by creating irregular “jumps” for the eye to make.

I have not read a study that supports or refutes this.

Anecdotal wisdom from the field of typography would have us believe that large gaps between consecutive lines will create vertical “rivers” of white space which draw the eye downwards as opposed to leading it to the right when the gaps between the words become larger than the space between the lines.

I have not read a study that supports or refutes this.

Anecdotal wisdom from the field of typography would also have us believe that the irregular shape of the right edge of a block of text helps us orient our eye on the page, assisting us in our return saccade to the next line.

I have not read a study that supports or refutes this.

I did however conducted a small experiment using eye tracking equipment which showed that when reading justified text, return saccades were less less accurate when compared to those while reading text set flush-left text. However, when reading the justified text, the duration of the landing fixations, and the distance of the correction saccades required in order to continue reading were very similar from line to line when compared to the landing fixations and correction saccades as seen when reading text set flush-left.

I hypothesize that this is because — despite the presence of an irregular rag in a flush-left setting — the distance and trajectory of the return saccade when reading justified text remains constant from line to line resulting in a muscle-memory of sorts.

I need to collect significantly more data to support or refute this hypothesis (feel free to scoop me. It would make a great thesis).

Long/short, what is published in typography books is largely anecdotal wisdom, not supported by scientific research. And the bulk of the research that is out there is very new, requiring further exploration before claims of any confidence can be made. For example, there is still no agreement regarding the legibility of serif compared sans-serif typefaces.

For a collection of peer-reviewed journal articles regarding typography and reading comprehension, see http://readthetype.com/literature.

(and I always set text flush left)

  • Great answer! Just wondering, how many words per line were you working with in your experiments? Also, are your experiments written up or published anywhere? (p.s. the web link to your site on your profile is missing the .com) Feb 22, 2013 at 14:56
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    I don’t recall exactly, but <65 characters per line (CPL) for the eye-tracking one. It was just a fun personal project and did not get followed up or published. My thesis, a different project entirely, is in the publication process so I really can’t say to much about it yet, and an old study where I replicated Stroop (1935) with fonts can be purchased here — ijg.cgpublisher.com/product/pub.154/prod.515. Thanks for the tip re my url!
    – Chris Dean
    Feb 22, 2013 at 15:08
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    inconsistent word spacing is a problem of your typesetting system, and not of justification. To see this, open any book older than 100 years, from times when typesetting was a handcraft.
    – yo'
    Feb 22, 2013 at 15:20
  • It is physically impossible to change a paragraph setting from justified to flush left without adjusting inter-word and inter-letter spacing. When set flush left, these units of space remain constant. When justified, they differ from line to line, based upon their length. Technology is orthogonal to this point.
    – Chris Dean
    Feb 22, 2013 at 15:27
  • @tohecz I think we're talking about inconsistent word spacing comparing different lines, not within each line - different spacing on different lines is unavoidable unless your justification only stretches the tracking between letters within words (not a good idea..) Feb 22, 2013 at 15:29

I don't justify any text which I wish to be easily read. Justification can decrease readability.

And a ragged-right, left aligned, text block is simply far more visually interesting than a block of text.

  • I agree that justification decreases readibility if you don't hyphenate the words. However, do you have any reference to studies that would confirm that properly hyphenated justified text decreases readability?
    – yo'
    Feb 22, 2013 at 18:41
  • No specific studies, simply experience based upon percent of return calculated by testing multiple sales pieces over 15+ years. Ragged right text has ALWAYS outperformed justified text here. In every instance, without fail. Even if a study were to claim otherwise, it would not alter my use fo flush left text due to the loss of sales justifying causes.
    – Scott
    Feb 22, 2013 at 23:52
  • This is strange. Do you speak about real books with long paragraphs?
    – yo'
    Feb 22, 2013 at 23:57
  • How is it strange? I have real world experience testing the return on investment for pieces I've designed. Nothing strange about it.
    – Scott
    Feb 23, 2013 at 1:31
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    Ok, I probably just don't understand English and don't know what "sales piece" is, with dictionaries nor Wiki being of help. Never mind, forget it.
    – yo'
    Feb 23, 2013 at 8:35

Your text of course ought to be justified. Two more things are necessary:

  • Proper hyphenation of words. This allows more even and better interword spaces.

  • Good line length, which should not exceed 66 characters per line in average. If lines are too long, the eye of a reader is often not able to move to the next line when reading the text and sometimes one line is skipped or the line is read twice, which confuses and distracts the reader.

This is not supported by a scientific study, just by hundreds of years of polishing the typography rules. To confirm this, open any well typeset book. (The ones older than 100 years work the best, because era of typewriters and computers did serious damage to good typography.)

Just an example of the same text typeset with different restrictions. The first text is the proper one, with hyphenation and micro typography. The second one has forbidden hyphenation and the third one is typeset raggedright. Only the first is acceptable, and "uneven interword spaces" is not an argument: They not really uneven to distract the reader, he actually doesn't even notice that there are any differences (click for better resolution):

click for better resolution

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    @JoeZeng I cannot tell you now where it comes from, I'll try to search for it later. Sure thing is that it has nothing to do with computers and their limitations. These typographical rules are couple centuries older than computers.
    – yo'
    Feb 22, 2013 at 15:17
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    @ClementHerreman The problem is that people think that there was no typography before typewriters, T602 and MS Word. But (almost all) typography rules are much much much older than that.
    – yo'
    Feb 22, 2013 at 16:41
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    I guess we need to educate them about the date of birth of Gutenberg ;) Feb 25, 2013 at 8:19
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    "Your text of course ought to be justified" = why?
    – DA01
    Apr 23, 2015 at 20:59
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    "Your text of course ought to be justified" Why? It may look better but it certainly doesn't help readability
    – Cai
    Nov 13, 2016 at 18:01

I'd like to suggest an experiment with line length that I found fascinating and possible since we are all typographers, now.

Using unformatted text, fill a text block flush left. The text will be ragged right. Gradually adjust the line measure, half-a-pica at a time. For example, 24 picas, 24.5, 25, 25.5, etc. You might want to start at a different place for your experiment.

There will be a point where suddenly the text will reflow to appear very nearly flush right. The line length will vary with the nature of the text. Novels will have a more narrow "comfortable" fit than technical documents that have longer technical words. With hyphenation, even long words can be broken into syllables to create very clean text blocks for various different typeface fonts and content combinations.

Only after discovering the "sweet-spot" for the actual combination of line length, average word length, and word space using the above incremental technique, turn on the justification.

There will be a very slight adjustment of the word spaces to accommodate the line endings. The result will be easily readable and clean looking.


  • Interesting idea. I could see this working on a small scale to inform your design (assuming the text was already finalized), but not sure how useful this advice is for long texts. Nov 14, 2016 at 12:50

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