This is Why Your WordPress add_image_size() Isn't Working
If you've ever tried to use the WordPress add_image_size()
function to create custom thumbnail sizes for your website, you may have run into some frustrating issues where the new thumbnail sizes just aren't showing up.
This is a really common problem that a lot of WordPress users and developers face, and it can be tricky to troubleshoot. But don't worry, we're here to help you get to the bottom of it.
In this article, we'll cover the most common reasons why add_image_size()
may not be working as expected, and provide you with step-by-step solutions to get it fixed.
Understanding add_image_size()
Before we dive in, let's quickly review how the add_image_size()
function works in WordPress.
add_image_size()
allows you to define custom image sizes that will be generated whenever you upload a new image to your WordPress media library. These custom sizes can then be used throughout your website, such as in your post thumbnails, gallery layouts, and more.
The function takes three arguments:
- Name: The name you want to give to the custom image size. This is how you'll reference the size later on in your theme or plugins.
- Width: The desired width of the image in pixels.
- Height: The desired height of the image in pixels.
You can also include two optional arguments:
- Crop: A boolean value (true/false) that determines whether the image should be cropped to the exact dimensions you specified, or if it should be resized to fit within those dimensions.
- Jpg_quality: An integer value between 0-100 that sets the quality of the JPEG image.
Here's an example of how you might use add_image_size()
:
add_image_size( 'custom-thumb', 300, 200, true );
This would create a new image size called "custom-thumb" that is 300px wide and 200px tall, and the image would be cropped to those exact dimensions.
Okay, now that we have the basics covered, let's dig into the common reasons why add_image_size()
might not be working as expected.
Reason 1: The function wasn't added at the right time
One of the most common reasons add_image_size()
doesn't work is that the function was added at the wrong time in the WordPress loading process.
The add_image_size()
function needs to be called before WordPress generates the initial image sizes. This typically means you need to add it in your theme's functions.php
file, or in a plugin that loads before your theme.
If you add the add_image_size()
function too late in the process, WordPress will have already generated the initial image sizes and won't create the new custom size you defined.
Solution: Make sure you're adding your add_image_size()
calls in the right place. The ideal spot is usually in the functions.php
file of your theme, or in the main file of a custom plugin.
Reason 2: The image wasn't regenerated after the size was added
Even if you've added the add_image_size()
function correctly, WordPress won't automatically regenerate your existing images to include the new custom size.
This means that any images you uploaded before defining the new size won't have the custom thumbnail available.
Solution: To generate the new custom thumbnail sizes for your existing images, you'll need to use a plugin like Regenerate Thumbnails or Bulk Resize Images. These plugins will go through your media library and generate the new custom sizes for all your existing images.
Alternatively, you can use a WordPress function called add_filter('intermediate_image_sizes_advanced', ...)
to programmatically add the new custom size to your existing images. Here's an example:
// Add the new custom size to the intermediate image sizes
add_filter( 'intermediate_image_sizes_advanced', function( $sizes ) {
$sizes['custom-thumb'] = array(
'width' => 300,
'height' => 200,
'crop' => true,
);
return $sizes;
});
This will add the "custom-thumb" size to your existing images, but it won't generate the new sizes for you. You'll still need to use a plugin like Regenerate Thumbnails to actually create the new thumbnails.
Reason 3: The image size isn't being used
Even if you've successfully added the new custom image size and regenerated your existing images, the size still may not be showing up on your website.
This is because you need to actually use the new image size in your theme or plugin code. Just adding the size doesn't automatically make it available for use.
Solution: Once you've added the new custom size, you'll need to update your theme or plugin code to reference and use the new size.
For example, if you're using the size in a post thumbnail, you might update your code like this:
the_post_thumbnail( 'custom-thumb' );
Or if you're using it in a custom image gallery, you might do something like this:
wp_get_attachment_image( $attachment_id, 'custom-thumb' );
The key is making sure you're using the exact name you specified when you called add_image_size()
.
Reason 4: The image size isn't being filtered correctly
In some cases, the new custom image size might be getting added correctly, but it's not being included in the list of available sizes that WordPress provides.
This can happen if you're using a plugin or theme that is filtering the available image sizes in a way that's excluding your new custom size.
Solution: To troubleshoot this, you can add the following code to your theme's functions.php
file or a custom plugin:
// Add the custom image size to the available image sizes
add_filter( 'image_size_names_choose', function( $sizes ) {
$sizes['custom-thumb'] = __( 'Custom Thumbnail', 'your-text-domain' );
return $sizes;
});
This will ensure that your new custom size is properly added to the list of available image sizes that users can select when inserting an image in the WordPress editor.
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Reason 5: The image size isn't being applied correctly
Finally, it's possible that the new custom image size is being generated, but it's not being applied correctly to the actual image.
This can happen if you have custom image processing or optimization plugins installed that are overriding the default WordPress image resizing behavior.
Solution: To troubleshoot this, you can try disabling any image optimization or processing plugins you have installed, and see if that resolves the issue. You can also try regenerating your images using a plugin like Regenerate Thumbnails to ensure the new size is being applied correctly.
If you're still having trouble, you can try adding the following code to your theme's functions.php
file or a custom plugin:
// Force WordPress to use the custom image size
add_filter( 'post_thumbnail_html', function( $html, $post_id, $post_thumbnail_id, $size, $attr ) {
if ( $size == 'custom-thumb' ) {
$image = wp_get_attachment_image_src( $post_thumbnail_id, 'custom-thumb' );
$html = '<img src="' . $image[0] . '" width="' . $image[1] . '" height="' . $image[2] . '" />';
}
return $html;
}, 10, 5 );
This will ensure that WordPress uses the custom image size you've defined, even if other plugins or themes are trying to override it.
Putting it all together
By following these steps, you should be able to get to the bottom of why your add_image_size()
function isn't working as expected. Remember, the key things to check are:
- Make sure you're adding the function at the right time, before WordPress generates the initial image sizes.
- Regenerate your existing images to include the new custom size.
- Ensure you're actually using the new custom size in your theme or plugin code.
- Check that the new size is being properly filtered and included in the list of available sizes.
- Verify that the new size is being applied correctly to the images.
If you're still having trouble, don't hesitate to reach out to the WordPress support community or consider using a tool like Flowpoint.ai to help identify and fix any technical issues that may be impacting your website's conversion rates.