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CSS CSS Basics (2014) Understanding Values and Units Em Units

Posted by Frans de Haan
Frans de Haan
5,193 Points

em or %?

I searched on the web for the difference between em en %, I found this article.

http://kyleschaeffer.com/development/css-font-size-em-vs-px-vs-pt-vs/

Can someone tell me why a lot of people use the em still.

Just like in this tutorial.

Friendly regards,

Frans de Haan,

1 Answer

Robert Stefanic
Robert Stefanic
35,170 Points
Robert Stefanic
Robert Stefanic
35,170 Points

It could be preference. I would personally suggest someone to use % over em, but using em isn't wrong.

It's just easier to reason about what's going on with %. If I'm reading someone's code, and I see a %, I know it's a percentage relative to the parent element. In my opinion, it's just easier to read, and therefore, it's easier to reason about.

When someone uses em, you have to take into account what the parent element's size is in pixels, and then do some math in order to figure out the value you want. Em is an abstraction of pixel values, and in order to figure out the size of an element, you have to think about what the parent's size is, and then multiply it by the em. It's just a bit odd to work with at times.