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Embed YouTube videos - the flexible way

Author: alex
Title: YouTube embedding with correct aspect and any width
Language: en-US
Created: 23:56 on Thursday, 31. August 2017
Modified: 23:56 on Thursday, 31. August 2017

This is a HowTo and deals with the problem of embedding YouTube videos at any desired size. The size of the video should be determined by the surrounding container. No fixed width and height values are needed.

Tags: firstcss
Page layout: no_sidebar
Last modified:
393 Words
23:56 | by alex
Reading time: approx. 1 minute(s).

It should be noted that this works on modern browsers only, where modern means anything newer than IE8 or so. Any modern version of Firefox, Chrome, Opera, Safari, IE, Edge and the zillion of Chromium based browsers will work.

It does not use object or embed tags, but instead embeds videos in an iframe element, which is the preferred way to embed a video that does not use flash.

The problem

We want a video that adopts to a given width and adjusts it’s height. We assume the aspect ratio at 16:9 (which is safe, because the YouTube player always uses it and videos of different format will be cropped or letterboxed accordingly) and the height should be set automatically from the given width.

Case 1, the video should take all available width.

<div class="ytcontainer">
    <iframe class="ytframe" frameborder="0" allowfullscreen 

The [ID] is a placeholder for the video ID on YouTube, which is the part that normally goes behind watch?v= in the full video URL.

div.ytcontainer {
    width: 100%;
    height: 0;
    padding-bottom: 56.25%;
    position: relative;

iframe.ytframe {
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    position: absolute;
What does it mean?

The magic is in ytcontainer, particularly in the zero height and the somewhat magic bottom padding value of 56.25 percent, which is exactly the aspect ratio of a 16:9 rectangle. The rectangle will have a content height of zero, but the padding will set its overall height to 56% of its width.

The other important thing to note is the position: absolute given to the iframe. This allows the iframe to fill the padding space in the enclosing div element and inherit the 16:9 ascpect ratio of the box.

Case 2, we want a custom width:

This isn’t much more difficult. The only thing you need to do is to wrap the above construct in one more div element and set its width to whatever you want.

<div style="width: 50%; margin: auto;">
	<div class="ytcontainer">
		<iframe class="ytframe" frameborder="0" allowfullscreen src="[ID]"></iframe>

This will do it. You get a centered (because of the margin: auto;) box at 50% of the available width with a properly sized video element.