Generally speaking, does there exist an "optimal" line height as a proportion of how high the text is, for maximum readability?

  • MS Word 2010 has a default of 1.5 lines, IIRC. I find it too much, though. It depends on the font. Fonts with large ascenders/desenders need a bit more line spacing. – Mateen Ulhaq Jan 6 '11 at 3:28
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    The answer to this is more complex than it might appear. For a start, there is not a single measure of type height - there's the 'point size' or em (which is a relative unit, fixed only with respect to a given typeface), the cap height, the ascender height, the x-height, etc... – e100 Jan 6 '11 at 14:26

1.2 ems is standard accepted for best readability. Often it gets to be a bit bigger on websites.


longer lines of text can benefit from more spacing as well (easier to find the next line as you're reading)

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    There isn't a 'standard' as it depends on many other factors--namely the type style, the line length, the size of the type, etc. '1.2' is a safe start, but not a universal rule by any means. – DA01 Feb 23 '13 at 0:56
  • definitely. I guess it depends how 'generally' we're speaking – Damon Feb 23 '13 at 0:58
  • Ha! True. Good point. "generally speaking" it's certainly a valid answer. – DA01 Feb 23 '13 at 1:15

For the block text I personally use this simple rule:

Vertical space between the lines (put in lowercase) should be ca. 180% of the height of the lowercase letters.

To illustrate the rule, I copy paste the letter "o" and fit it between the lines:

enter image description here

So the optimal spacing IMO is when I can fit slightly less than two whole letters between the lines.

However, one should be aware of the fact that the number (line height) is not even related to the optical line height (lowercase height), but normally related to the so-called em-height, so it is better just to look at the actual result and adjust accordingly.

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