Scale image to fit a bounding box

Is there a css-only solution to scale an image into a bounding box (keeping aspect-ratio)? This works if the image is bigger than the container:

img {
  max-width: 100%;
  max-height: 100%;
}

Example:

• Use case 1 (works): http://jsfiddle.net/Jp5AQ/2/
• Use case 2 (works): http://jsfiddle.net/Jp5AQ/3/

But I want to scale up the image until a dimension is 100% of the container.

• Use case 3 (doesn't work): http://jsfiddle.net/Jp5AQ/4/

Thanks to CSS3 there is a solution !

The solution is to put the image as background-image and then set the background-size to contain.

HTML

<div class='bounding-box'>
</div>

CSS

.bounding-box {
  background-image: url(...);
  background-repeat: no-repeat;
  background-size: contain;
}

Test it here: http://www.w3schools.com/cssref/playit.asp?filename=playcss_background-size&preval=contain

Full compatibility with latest browsers: http://caniuse.com/background-img-opts

To align the div in the center, you can use this variation:

.bounding-box {
  background-image: url(...);
  background-size: contain;
  position: absolute;
  background-position: center;
  background-repeat: no-repeat;
  height: 100%;
  width: 100%;
}

Note: Even though this is the accepted answer, the answer below is more accurate and is currently supported in all browsers if you have the option of using a background image.

Edit 2: In the modern age, using object-fit might be an even better solution: https://developer.mozilla.org/en-US/docs/Web/CSS/object-fit

No, there is no CSS only way to do this in both directions. You could add

.fillwidth {
    min-width: 100%;
    height: auto;
}

To the an element to always have it 100% width and automatically scale the height to the aspect ratio, or the inverse:

.fillheight {
    min-height: 100%; 
    width: auto;
}

to always scale to max height and relative width. To do both, you will need to determine if the aspect ratio is higher or lower than it's container, and CSS can't do this.

The reason is that CSS does not know what the page looks like. It sets rules beforehand, but only after that it is that the elements get rendered and you know exactly what sizes and ratios you're dealing with. The only way to detect that is with JavaScript.

---

Although you're not looking for a JS solution I'll add one anyway if someone might need it. The easiest way to handle this with JavaScript is to add a class based on the difference in ratio. If the width-to-height ratio of the box is greater than that of the image, add the class "fillwidth", else add the class "fillheight".

$('div').each(function() {
  var fillClass = ($(this).height() > $(this).width()) 
    ? 'fillheight'
    : 'fillwidth';
  $(this).find('img').addClass(fillClass);
});

.fillwidth { 
  width: 100%; 
  height: auto; 
}
.fillheight { 
  height: 100%; 
  width: auto; 
}

div {
  border: 1px solid black;
  overflow: hidden;
}

.tower {
  width: 100px;
  height: 200px;
}

.trailer {
  width: 200px;
  height: 100px;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div class="tower">
  <img src="http://placekitten.com/150/150" />
</div>
<div class="trailer">
  <img src="http://placekitten.com/150/150" />
</div>

Here's a hackish solution I discovered:

#image {
	max-width: 10%;
	max-height: 10%;
	transform: scale(10);
}

This will enlarge the image tenfold, but restrict it to 10% of its final size - thus bounding it to the container.

Unlike the background-image solution, this will also work with <video> elements.

Interactive example:

 function step(timestamp) {
	 var container = document.getElementById('container');
	 timestamp /= 1000;
	 container.style.left   = (200 + 100 * Math.sin(timestamp * 1.0)) + 'px';
	 container.style.top    = (200 + 100 * Math.sin(timestamp * 1.1)) + 'px';
	 container.style.width  = (500 + 500 * Math.sin(timestamp * 1.2)) + 'px';
	 container.style.height = (500 + 500 * Math.sin(timestamp * 1.3)) + 'px';
	 window.requestAnimationFrame(step);
 }

 window.requestAnimationFrame(step);

 #container {
	 outline: 1px solid black;
	 position: relative;
	 background-color: red;
 }
 #image {
	 display: block;
	 max-width: 10%;
	 max-height: 10%;
	 transform-origin: 0 0;
	 transform: scale(10);
 }

<div id="container">
	<img id="image" src="https://upload.wikimedia.org/wikipedia/en/7/7d/Lenna_%28test_image%29.png">
</div>

Today, just say object-fit: contain. Support is everything but IE: http://caniuse.com/#feat=object-fit

html:

	<div class="container">
      <img class="flowerImg" src="flower.jpg">
	</div>

css:

.container{
  width: 100px;
  height: 100px;
}


.flowerImg{
  width: 100px;
  height: 100px;
  object-fit: cover;
  /*object-fit: contain;
  object-fit: scale-down;
  object-position: -10% 0;
  object-fit: none;
  object-fit: fill;*/
}

You can accomplish this with pure CSS and complete browser support, both for vertically-long and horizontally-long images at the same time.

Here's a snippet which works in Chrome, Firefox, and Safari (both using object-fit: scale-down, and without using it):

figure {
  margin: 0;
}

.container {
  display: table-cell;
  vertical-align: middle;
  width: 80px;
  height: 80px;
  border: 1px solid #aaa;
}

.container_image {
  display: block;
  max-width: 100%;
  max-height: 100%;
  margin-left: auto;
  margin-right: auto;
}

.container2_image2 {
  width: 80px;
  height: 80px;
  object-fit: scale-down;
  border: 1px solid #aaa;
}

Without `object-fit: scale-down`:

<br>
<br>

<figure class="container">
  <img class="container_image" src="https://i.imgur.com/EQgexUd.jpg">
</figure>

<br>

<figure class="container">
  <img class="container_image" src="https://i.imgur.com/ptO8pGi.jpg">
</figure>

<br> Using `object-fit: scale-down`:

<br>
<br>

<figure>
  <img class="container2_image2" src="https://i.imgur.com/EQgexUd.jpg">
</figure>

<br>

<figure>
  <img class="container2_image2" src="https://i.imgur.com/ptO8pGi.jpg">
</figure>

Another solution without background image and without the need for a container (though the max sizes of the bounding box must be known):

img{
  max-height: 100px;
  max-width: 100px;
  width: auto;    /* These two are added only for clarity, */
  height: auto;   /* as the default is auto anyway */
}

---

If a container's use is required, then the max-width and max-height can be set to 100%:

img {
    max-height: 100%;
    max-width: 100%;
    width: auto; /* These two are added only for clarity, */
    height: auto; /* as the default is auto anyway */
}

div.container {
    width: 100px;
    height: 100px;
}

For this you would have something like:

<table>
    <tr>
        <td>Lorem</td>
        <td>Ipsum<br />dolor</td>
        <td>
            <div class="container"><img src="image5.png" /></div>
        </td>
    </tr>
</table>

This example to stretch the image proportionally to fit the entire window. An improvisation to the above correct code is to add $( window ).resize(function(){});

function stretchImg(){
	$('div').each(function() {
	  ($(this).height() > $(this).find('img').height()) 
		? $(this).find('img').removeClass('fillwidth').addClass('fillheight')
		: '';
	  ($(this).width() > $(this).find('img').width()) 
		? $(this).find('img').removeClass('fillheight').addClass('fillwidth')
		: '';
	});
}
stretchImg();

$( window ).resize(function() {
	strechImg();
});

There are two if conditions. The first one keeps checking if the image height is less than the div and applies .fillheight class while the next checks for width and applies .fillwidth class. In both cases the other class is removed using .removeClass()

Here is the CSS

.fillwidth { 
   width: 100%;
   max-width: none;
   height: auto; 
}
.fillheight { 
   height: 100vh;
   max-width: none;
   width: auto; 
}

You can replace 100vh by 100% if you want to stretch the image with in a div. This example to stretch the image proportionally to fit the entire window.

Are you looking to scale upwards but not downwards?

div {
    border: solid 1px green;
    width: 60px;
    height: 70px;
}

div img {
    width: 100%;
    height: 100%;
    min-height: 500px;
    min-width: 500px;
    outline: solid 1px red;
}

This however, does not lock aspect-ratio.

I have used table to center image inside the box. It keeps aspect ratio and scales image in a way that is totally inside the box. If the image is smaller than the box then it is shown as it is in the center. Below code uses 40px width and 40px height box. (Not quite sure how well it works because I removed it from another more complex code and simplified it little bit)

.SmallThumbnailContainer {
  display: inline-block;
  position: relative;
  float: left;
  width: 40px;
  height: 40px;
  border: 1px solid #ccc;
  margin: 0px;
  padding: 0px;
}

.SmallThumbnailContainer {
  width: 40px;
  margin: 0px 10px 0px 0px;
}

.SmallThumbnailContainer tr {
  height: 40px;
  text-align: center;
}

.SmallThumbnailContainer tr td {
  vertical-align: middle;
  position: relative;
  width: 40px;
}

.SmallThumbnailContainer tr td img {
  overflow: hidden;
  max-height: 40px;
  max-width: 40px;
  vertical-align: middle;
  margin: -1px -1px 1px -1px;
}

<table class="SmallThumbnailContainer" cellpadding="0" cellspacing="0">
  <tr>
    <td>
      <img src="https://www.gravatar.com/avatar/bf7d39f4ed9c289feca7de38a0093250?s=32&d=identicon&r=PG" width="32" height="32" alt="OP's SO avatar image used as a sample jpg because it is hosted on SO, thus always available" />
    </td>
  </tr>
</table>

Note: the native thumbnail size in this snippet is 32px x 32px, which is smaller than its 40px x 40px container. If the container is instead sized smaller than the thumbnail in any dimension, say 40px x 20px, the image flows outside the container in the dimensions that are smaller than the corresponding image dimension. The container is marked by a gray 1px border.

The cleanest and simplest way to do this:

First some CSS:

div.image-wrapper {
    height: 230px; /* Suggestive number; pick your own height as desired */
    position: relative;
    overflow: hidden; /* This will do the magic */
    width: 300px; /* Pick an appropriate width as desired, unless you already use a grid, in that case use 100% */
}
img {
    width: 100%;
    position: absolute;
    left: 0;
    top: 0;
    height: auto;
}

The HTML:

<div class="image-wrapper">
  <img src="yourSource.jpg">
</div>

This should do the trick!

This helped me:

.img-class {
  width: <img width>;
  height: <img height>;
  content: url('/path/to/img.png');
}

Then on the element (you can use javascript or media queries to add responsiveness):

<div class='img-class' style='transform: scale(X);'></div>

Hope this helps!

Use Object Fit on both div and img to scale image

<div class="box"><img src="image.jpg"></div>

.box {height: auto;
object-fit: cover;} 

img { height: 100%; object-fit: cover; }

This worked for my needs, doesn't flatten out the image while setting height limitation, it overflows instead.

.top-container{
       width:50%;
    }
.img-container {
        display: flex;
        justify-content: center;
        align-items: center;
        height: 40vh;
        width: 100%;
        overflow: hidden;
    }
    
    .img-container img {
        max-width: 10%;
        max-height: auto;
        transform: scale(10);
    }

<div class='top-container'>
 <div class='img-container'>
  <img src='image.jpg'>
 </div>
</div>

.boundingbox {
    width: 400px;
    height: 500px;
    border: 2px solid #F63;
}
img{
    width:400px;
    max-height: 500px;
    height:auto;
}

I'm editing my answer to further explain my soluton as I've got a down vote.

With the styles set as shown above in css, now the following html div will show the image always fit width wise and will adjust hight aspect ratio to width. Thus image will scale to fit a bounding box as asked in the question.

<div class="boundingbox"><img src="image.jpg"/></div>