I published an updated version of this article for 2019 here.
This tutorial shows you how to change WooCommerce product image sizes, to make your online shop look outstanding.
This process actually is very straightforward:
First you login to your WordPress admin area.
Go to "WooCommerce" -> "Settings" in the menu on the left. Usually, the "WooCommerce" menu item appears below the "Comments" item.
To change the WooCommerce product image size, scroll down on the "Settings" page until you see the following:
Here you can change the WooCommerce image size for specific needs:
Catalog Images - the medium sized thumbnails used in all product loops (e.g. categories, related products, up sells, cross sells, etc.).
Single Product Image - The largest thumbnails used on the product details page
Product Thumbnails - they're used in product galleries on the single product pages, the cart, and widgets.
(Descriptions coming from the WooCommerce documentation.)
After you changed the WooCommerce product image sizes, you need to regenerate the thumbnails.
Therefore you can use a free plugin called Regenerate Thumbnails by Viper007Bond. Simply go to the "Plugins" menu item and install it from the repository.
Once you installed it, you can go to "Tools" -> "Regen. Thumbnails" in the admin menu and click the "Regenerate All Thumbnails" button.
There you go!
If you experience any issues, leave a comment below.
Make sure you upload properly-sized product images to your WooCommerce. Using the wrong dimensions will make the images look bad, even when you configured the right sizes.