The WordPress featured image field is a very powerful tool within WordPress. Even the best tools can be improved on though. Many times it can be very helpful to give a set of recommend dimensions to the user. Giving this information can help the client adjust their image to make sure it looks exactly as they are picturing when they upload the image.
Our goal is to take the default Featured Image field label
and add a bit more information to it.
Here’s the code, and I hope this helps!