Maintain Aspect Ratio According to Width and Height

Maintain aspect ratio according to width and height

The aspect-ratio property (2022)

To maintain the aspect ratio of a div according to width and height, you can use the aspect-ratio property (MDN reference).

This allows you to maintain any aspect ratio according to the viewport size or to the size of the parent element.

Maintaining aspect-ratio according to the viewport size (width and height) :

.ar-1-1 {
  aspect-ratio: 1 / 1;
  background: orange;
}

.ar-1-19 {
  aspect-ratio: 16 / 9;
  background: pink;
}

div {
  max-width: 100vw;
  max-height: 100vh;
  margin-bottom: 5vh;
}


/** For the demo **/

body {
  margin: 0;
}

<div class="ar-1-1">Aspect ratio 1:1</div>
<div class="ar-1-19">Aspect ratio 1:19</div>

Maintain div aspect ratio according to height

You can use an image that has the desired proportions as to help with proportional sizing (images can be scaled proportionally by setting one dimension to some value and other to auto). The image does not have to be visible, but it must occupy space.

.box {  position: absolute;  bottom: 0;  left: 0;  height: 50%;}.size-helper {  display: block;  width: auto;  height: 100%;}.inner {  position: absolute;  top: 0;  bottom: 0;  left: 0;  right: 0;  background: rgba(255, 255, 153, .8);}

<div class="box">  <img class="size-helper" src="//dummyimage.com/200x100/999/000" width="200" height="100">  <div class="inner">    1. box has fluid height<br>    2. img has 2:1 aspect ratio, 100% height, auto width, static position<br>    2.1 it thus maintains width = 200% of height<br>    2.2 it defines the dimensions of the box<br>    3. inner expands as much as box  </div></div>

CSS force image resize and keep aspect ratio

img {  display: block;  max-width:230px;  max-height:95px;  width: auto;  height: auto;}

<p>This image is originally 400x400 pixels, but should get resized by the CSS:</p><img width="400" height="400" src="http://i.stack.imgur.com/aEEkn.png">

Maintain aspect ratio of a div according to height

As % padding/margin are calculated according to the width of the contrainer, you can't use the "padding technique" to maitain aspect ratio according to the height.

For a CSS solution, you will have to use vh units :

vh : 1/100th of the height of the viewport.

Source

For browser support see canIuse

Example for a 1:1 aspect ratio :

DEMO

CSS

div{
    width: 50vh;
    height: 50vh;
}

Maintain the aspect ratio of a div with CSS

Just create a wrapper <div> with a percentage value for padding-bottom, like this:

.demoWrapper {
  padding: 10px;
  background: white;
  box-sizing: border-box;
  resize: horizontal;
  border: 1px dashed;
  overflow: auto;
  max-width: 100%;
  height: calc(100vh - 16px);
}

div {
  width: 100%;
  padding-bottom: 75%;
  background: gold; /** <-- For the demo **/
}

<div class="demoWrapper">
  <div></div>
</div>

Maintain aspect ratio of div but fill screen width and height in CSS?

There is now a new CSS property specified to address this: object-fit.

https://developer.mozilla.org/en-US/docs/Web/CSS/object-fit

The feature is widely supported by now (http://caniuse.com/#feat=object-fit).

Maintain Aspect ratio for width @ 100%

Remove the height from the image and give your container height: auto;. Check the snippet.

div{  width: 1000px;  height: auto;  background: black;}
img {  width: 100%;}

<div>      <img  src="https://dummyimage.com/500x250/918c91/0011ff.jpg" /></div>

Maintain Aspect Ratio According to Width and Height