How to convert px into em in CSS?

CSS | Convert px into em: In this tutorial, we will learn about the px and em units and how to convert px into em in CSS. By Anjali Singh Last updated : July 11, 2023


We use pixels with almost every scaling property like width, height, etc. Although you don't need to use pixels as a unit while sizing your element as you can use various other units like em or percentage. But pixels, as you might have noticed, is the most used measuring unit. Any beginner who has just started web development must start from pixels and then explore further units. Here in this article we will not just discuss pixels but will also discuss how we can convert one unit to another in CSS.

Pixels (px) and Ems (em) in CSS

Pixels are used widely as a unit while sizing and shaping an image. It is widely used with various images, so if you are planning to resize an image you must go for using pixels as a unit. But if you have been using pixels for a long time, then it is time that you explore other units as well. You can start with the em. Now the catch here is that these two units are not at all equivalent, what it means that if you set the height of an element to 50px then if you change the height to 50em, you will not get the same result. These two units are very different. Now, you must be wondering since these two units are so different than how would anyone who is not aware of the "em" units be able to implement it?

Well, the question is apt and so is the solution. Read the next section to find out the answer!

CSS px to em conversion

Well, the solution to this problem is very simple. All you need to do is convert the pixel value to em. That's right, just like any conversion you can also convert pixels to em. Like you convert meters to centimeters etc. So how do we convert pixels into em? There are some simple steps to do that, so let us move on with that part.


  1. You can set a default pixel size first.
  2. Second, by taking the reference from the default pixel size you can convert the pixels into ems.
  3. This technique is also possible vice versa i.e. you can set default em size and convert em to pixels.

Pretty cool right? Who would have thought that we can convert these units just like any mathematical units! So, why don't you give it a try? As a tip, you can always set the default pixel as 16px.

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