Resize image proportionally with CSS?

Is there a way to resize (scale down) images proportionally using ONLY CSS?

I'm doing the JavaScript way, but just trying to see if this is possible with CSS.

To resize the image proportionally using CSS:

img.resize {
    width:540px; /* you can use % */
    height: auto;
}

Control size and maintain proportion :

#your-img {
    height: auto; 
    width: auto; 
    max-width: 300px; 
    max-height: 300px;
}

If it's a background image, use background-size:contain.

Example css:

#your-div {
  background: url('image.jpg') no-repeat;
  background-size:contain;
}

Try

transform: scale(0.5, 0.5);
-ms-transform: scale(0.5, 0.5);
-webkit-transform: scale(0.5, 0.5);

You can use object-fit property:

.my-image {
    width: 100px;
    height: 100px;
    object-fit: contain;
}

This will fit image, without changing the proportionally.

Notice that width:50% will resize it to 50% of the available space for the image, while max-width:50% will resize the image to 50% of its natural size. This is very important to take into account when using this rules for mobile web design, so for mobile web design max-width should always be used.

UPDATE: This was probably an old Firefox bug, that seems to have been fixed by now.

To scale an image by keeping its aspect ratio

Try this,

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

Revisited in 2015:

<img src="http://imageurl" style="width: auto; height: auto;max-width: 120px;max-height: 100px">

I've revisited it as all common browsers now have working auto suggested by Cherif above, so that works even better as you don't need to know if image is wider than taller.

older version: If you are limited by box of 120x100 for example you can do

<img src="http://image.url" height="100" style="max-width: 120px">

<img style="width: 50%;" src="..." />

worked just fine for me ... Or am I missing something?

Edit: But see Shawn's caveat about accidentally upsizing.

The css properties max-width and max-height work great, but aren't supported by IE6 and I believe IE7. You would want to use this over height / width so you don't accidentally scale an image up. You would just want to limit the maximum height/width proportionately.

img{
    max-width:100%;
    object-fit: scale-down;
}

works for me. It scales down larger images to fit in the box, but leaves smaller images their original size.

I believe this is the easiest way to do it, also possible using through the inline style attribute within the <img> tag.

.scaled
{
  transform: scale(0.7); /* Equal to scaleX(0.7) scaleY(0.7) */
}

<img src="flower.png" class="scaled">

or

<img src="flower.png" style="transform: scale(0.7);">

Use this easy scaling technique

img {
	max-width: 100%;
	height: auto;
}
@media {
  img { 
  	width: auto; /* for ie 8 */
  }
}

img {
    max-width:100%;
}

div {
    width:100px;
}

with this snippet you can do it in a more efficient way

We can resize image using CSS in the browser using media queries and the principle of responsive design.

    @media screen and (orientation: portrait) {
img.ri {
    max-width: 80%;
  }
}

@media screen and (orientation: landscape) {
  img.ri { max-height: 80%; }
}

You always need something like this

html
{
	width: 100%;
	height: 100%;
}

at the top of your css file

Try this:

div.container {
    max-width: 200px;//real picture size
    max-height: 100px;
}

/* resize images */
div.container img {
    width: 100%;
    height: auto;
}

image_tag("/icons/icon.gif", height: '32', width: '32') I need to set height: '50px', width: '50px' to image tag and this code works from first try note I tried all the above code but no luck so this one works and here is my code from my _nav.html.erb:
<%= image_tag("#{current_user.image}", height: '50px', width: '50px') %>