How to Add Additional Thumbnail Size Images in WordPress

A short tutorial on how to create additional thumbnail sizes for WordPress. Create and Generate Thumbnails for WordPress.

In order to create custom thumbnails for WordPress theme you need to ensure that you have Thumbnail Support Enabled. 

In your functions.php file you should this:

add_theme_support( 'post-thumbnails' );

To add additional sizes you need to add this

add_image_size( ‘name-of-size’, width, height, crop mode );

These are some examples of crops you can do to your images. 

add_image_size( 'sidebar-thumb', 120, 120, true ); // Hard Crop Mode
add_image_size( 'homepage-thumb', 220, 180 ); // Soft Crop Mode
add_image_size( 'singlepost-thumb', 590, 9999 ); // Unlimited Height Mode

After this you need to generate your Thumbnail with a plugin called: Regenerate Thumbnails

If you want more info on this tutorial check these out: