Finding the perfect paragraph indentation size

[Argon]

After having to add paragraph indentation to a self-published e-book version of a web serial that had neither space between paragraphs nor first-line indentation (and learning way more about CSS and e-book publishing than I ever thought I would want to know), I realized that I don't know what indentation size I prefer.

The truth of it is that you can get used to almost anything (except for a complete lack of paragraph differentiation!), particularly in light of past Kindle Store purchases—they're all wildly all over the place. Full line spacing is probably ideal for web, but on an e-reader, it's an unnecessary waste of space; moreover, most physical books use first-line indentation.

What is the ideal size? Butterick's Practical Typography suggests that

Typically, a first-line indent should be no smaller than the current point size, or else it’ll be hard to notice. It should be no bigger than four times the point size, or else the first line will seem disconnected from the left edge. So a paragraph set in 12 point should have a first-line indent of 12–48 points. (Recall that there are 72 points to an inch, so this works out to 0.17–0.67″.)

I played around with the e-book in question and found that I think that 1(r)em is too small, 1.5em is slightly too big, and one book that is probably close to right uses 5%, which is ever-so-slightly more than 1.25em. (What is 5% in ems, anyway? Is there an advantage in defining text-indent with one unit over the over?)

What do you use when creating or customizing e-books?

[ElspethB]

The first thing I do after buying a book is to import it into Calibre (de-DRMing it at the same time) and take a look at the CSS. My favorite paragraph indent value is 1.2 em. As you said, 1 em seems slightly too small and 1.5 slightly too big. For me (and Goldilocks), 1.2 is just right.

[Argon]

Doesn't an indentation defined in em change depending on the font size you choose, though? Have you ever considered using %?

[hobnail]

Originally Posted by Argon

Doesn't an indentation defined in em change depending on the font size you choose, though? Have you ever considered using %?

But isn't basing the indentation on the font size what you'd want?

I don't know what the spec says so I did some experimenting and an indent using percentage seems to be based on the line width. If someone with poor eyesight increases the point size of the text, they'd get a small indentation relative to the text size when percentage is used.

Personally I think the amount of indentation is yet another preference thing, like sans serif versus serif fonts, ragged-right versus justified, etc. I prefer an indentation of 2em.

[Sirtel]

1em for me. Always. Never bigger.

[Ripplinger]

I'm a 1.2'er as well.

[ps67]

1.5 em for me, not more, I can accept 1.2, not less.

[ZodWallop]

I use .3in (not .3em). It works for me.

I look at the formatting of every book in Calibre before I send it to my Kobo. But I only mess with formatting if indent is too small/large/doesn't exist, text isn't justified or if there is space between paragraphs.

[doubleshuffle]

1.2em all the way.

[JSWolf]

Originally Posted by Argon

Doesn't an indentation defined in em change depending on the font size you choose, though? Have you ever considered using %?

% is a really bad idea. It changes based on the screen being used. And you get it right on one screen and move to another and it can be different.

I prefer 1.2em. Simon & Schuster also uses 1.2em for their Star Trek eBooks.

It seems that most who have replied prefer 1.2em for an indent.

[DNSB]

I use 4%. A pox on all those dEMon worshipping em users.

[Apache]

It doesn't matter to me. When I read I don't see indentations or anything else.
Apache

[theducks]

1.5 or 2em
MM <2em

[hobnail]

Originally Posted by Apache

It doesn't matter to me. When I read I don't see indentations or anything else.
Apache

I could format a book where words alternate between normal, bold, and italic and see how long it takes to drive you crazy.

But seriously I'm like that as well even though I always reformat my books to meet my standards; indented paragraphs, no extra white space between them, ragged right, and all font-family stuff deleted. Then one time I had been reading a book for at least an hour or more and then I noticed that the right margin was straight (justified) and there was extra white space between the paragraphs. So much for my fussy standards.

[JSWolf]

Originally Posted by hobnail

I could format a book where words alternate between normal, bold, and italic and see how long it takes to drive you crazy.

But seriously I'm like that as well even though I always reformat my books to meet my standards; indented paragraphs, no extra white space between them, ragged right, and all font-family stuff deleted. Then one time I had been reading a book for at least an hour or more and then I noticed that the right margin was straight (justified) and there was extra white space between the paragraphs. So much for my fussy standards.

I remove the extra space for chapter titles, make sire the indents are 1.2em, remove paragraph space. Remove most embedded fonts (depends on the fonts), remove any left justification, make sure the base font size is set to the default, remove line-height except for drop caps, and some other cleaning up. All in all, when I am done, it's a much nicer read as the formatting can then be ignored.