How to Add Custom Image Sizes to the Dropdown in WordPress

When you upload an image to WordPress, you can choose the image size from a dropdown from the media section. There are typically a few predefined sizes. Namely:

  1. Thumbnail (150×150)
  2. Medium (325×225)
  3. Large (1024×766)

There might be some others as defined by your theme or plugins. Often however, you want a specific image dimension that fits well with your theme. It isn’t always easy to crop them in advance because of the different ways that screen DPIs function. What might be a reasonable size on your screen (a high DPI device like Microsoft’s Surface for example) could turn out to be huge when finally uploaded onto your site. As a result, you might need to constantly resize your images to custom dimensions.

Old Way – Forced to Use a Custom Size

Under regular circumstances, unless your desired image size exactly matches one of the options in the dropdown box, you’re forced to manually enter a custom image size. For example, by clicking on the “Edit” pencil icon on an image in the visual editor and choosing “Custom Size” like this:

Manual Entry of Custom Image Dimensions in WordPress

Here, you can specify the custom dimensions in the two boxes for width and height. If it’s just a one-off image dimension, then it’s fine. But if these dimensions apply to every single image that you upload to your blog, it can get very tedious. What we need to do is have a new custom image size so that we can just select it from the drop down box like “Large”, “Medium” etc.

New Method: Adding a  Custom Image Dimension to the Drop Down Box

Open up your functions.php file, or your custom plugin for PHP code and add the code below. If you don’t know how to add code like this, check out my tutorial on adding code snippets to WordPress. Here’s what you need to enter:

function setup_new_image_size() {
    if ( function_exists( 'add_image_size' ) ) {
        add_image_size( 'new-image', 550, 0, false );
add_action( 'after_setup_theme', 'setup_new_image_size' );

function add_image_size_to_media($sizes){
    $custom_sizes = array(
    'new-image' => '550 Image'
    return array_merge( $sizes, $custom_sizes );
add_filter('image_size_names_choose', 'add_image_size_to_media');

Replace the parts in bold with your desired image size and the name you want to show in the drop down box. Save your changes. Now the next time you upload an image, you should see a new entry in the image dropdown box with your name and custom dimensions as shown here:

Custom Image Sizes Added to Media Dropdown in WordPress

And so it works! Now there’s no need for you to constantly type in the custom dimensions for each and every image that you upload to WordPress. Just choose your new selection and you’re ready to go!

If you have a large number of images on your blog, and you exclusively use WordPress, you can speed things up by opting for specialized WordPress hosting instead of regular shared hosting. Here are some price comparisons to help you out.

About Bhagwad Park

I've been writing about web hosting and WordPress tutorials since 2008. I also create tutorials on Linux server administration, and have a ton of experience with web hosting products. Contact me via e-mail!

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