Fixing Units of Measure When Exporting ePub Files Via InDesign CC

I’ve been using InDesign to export my print files to ePub, which has saved me lots of time and given me some decent results. So far the only problem I’ve had with InDesign is that it exports measurements in px and not em, which I didn’t think was a problem until I viewed the ePub files on my phone (which is where I read books anyhow). What I noticed was that the first line indent was fine when viewed on a web browser or on a computer, but not on my phone. This was odd, so I looked at the stylesheet and found that all units of measurement were in px.

Now, px stands for pixel, and a pixel is a different size depending on the monitor you’re using to view the text. I actually didn’t think this would be a problem until I changed the measurements from px to em. Once I did this, the measurements were accurate on every device I viewed it in (Nook, Web browser and Play Books). The problem was solved.

Why InDesign would use a unit of measure that’s not known for print (px) is beyond me, but that’s what it does. It converts picas to px and not em, which is used with print. Measurements in px are used in web design, but for some reason doesn’t always translate well to eBooks.

Here’s an example of the CSS used for one element of a stylesheet once px was changed to em. Please note that this is not a 1:1 conversion. The em measure is based on the letter M in the parent font. If a parent font is not specified, then it goes by the font designated in the browser or eReader.

p.text {

font-family:“Times New Roman”, serif;


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