Custom Thumbnail Sizes in WordPress
If you’re uploading pretty big images for full-width post thumbnails or large post background images then resizing the thumbnails for use on other parts of the site is a must.
Let’s say, for example, your post thumbnails are 900px wide. You don’t want them that big for performance reasons if they’re only going to be shown at 300px wide (maximum). Here’s how to resize (this does leave an unlimited height which is proportional to the original size):
add_image_size('post-thumb-mini', 150); add_image_size('post-thumb-small', 300); add_image_size('post-thumb-medium', 600);
You can also crop the thumbnail to the desired size if unlimited, proportional height isn’t what you’re after.
add_image_size('post-thumb-mini', 300, 200, true); // Hard crop mode add_image_size('post-thumb-mini', 300, 200); // Soft crop mode
Hard Crop Mode
This cuts the image off at the specified height and doesn’t crop proportionally. If you specify
300, 200, true it will be shown at exactly that size.
Soft Crop Mode
This proportionally resizes the image and doesn’t cut off or distort any part of the image. If you specify
300, 200 it will be shown at roughly that size