By default, all the image thumbnail options are disabled, but you can choose what size you want to use and is based on whatever Blog Style and Layout you choose. You get three options to choose but only one is needed. However, if you think at some point in time you might change your blog’s style, you can enable the other options so that when you make the change, your blog will display the adjusted featured image size for each post.
NOTE I should mention that if you choose not to create thumbnails, any photo you upload will be used in the size and orientation that you originally uploaded.
- Go to Appearance >> Customize >> Thumbnail Options
- Make your choice from the listings of thumbnail options
- Click “Save & Publish“
Featured Image Size Reference
This will help give you a sizing reference if you decide to enable any of the options below. If you leave them unchecked, any featured image you upload for a blog post will be the size and orientation you upload.
- Standard creates featured images at 750×475 pixels
- Centered creates featured images at 1140×625 pixels
- Full Post Thumbnail creates images at 1140×500 pixels – this is for the full post if you want a consistent size across all posts.
Depending on the blog layout you choose, I recommend using the best photos as possible when uploading and to make sure they are at least the sizes mentioned above. Images will be cropped, so that is something to also remember when deciding on what kind of photos you plan to upload.
Re-Generate Thumbnails
There may be times you need to re-create your featured images with the cropped settings, either from the theme or from the WordPress Media Settings. The most popular plugin to use is called Regenerate Thumbnails.
This let’s you re-create the corrected sizes…providing your original image uploads are large enough they can be cropped correctly.