The Guide to Featured Image Size – How to Change it in WordPress

In a modern online world, everything consists of media files. Although videos have started to take over the Internet, images are still a vital component that you can’t live without. Whatever site you open, it should have at least a few pictures attached to it. Media files enrich posts and homepages, and you will remind yourself of the importance of media files whenever you stumble upon a site without ones. They make the entire blog look more vibrant and appealing to an average visitor.

But when it comes to WordPress and blog posts, there’s a unique image type that every blogger should put more emphasis on. We are talking about featured images. If you are still not quite familiar with them, please see what is a featured image and learn how to add one in WordPress.

The guide to featured image size

Usually, featured images are controlled by the theme. Whether you are going to have one, how many size options will you get and where it is going to appear, depends entirely on your theme developer. Unfortunately, not all developers tend to give featured images enough attention. So, in some cases, you will have to make adjustments to the featured image size. In other cases, you will need an extra dimension set to accommodate a plugin, new widget or some other area of your site that you want to customize.

While registering new image sizes is a piece of cake for a WordPress developer, it can be a nightmare to a non-coder. So, in this tutorial, we are not going to show you code snippets. Instead, we will show you how basic settings work, and how to extend the functionality of featured images through a free WordPress plugin.

Basic image settings

For starters, you should know that WordPress allows you to change a few basic media settings that will affect all new images that you upload to the site. By default, every WordPress installation works with just four image sizes:

  • The original size
  • Thumbnail
  • Medium
  • Large

Basic image settings

Once you upload a new image, WordPress will store the original file without modifications done to it. After the data transfer, the system will take that original file and make all the extra dimensions that you have set up in the Media Settings. It can also add a few extra sizes that are registered by the theme that you are using which might not be visible in the media settings.

To access the Media Settings, please navigate to Settings -> Media

The thumbnail image is somewhat unique. It is squared, and no matter the dimension you have set, WordPress will center on the portion of the picture and crop it to get needed dimensions. Some themes may use this preset as a featured image.

When it comes to medium and large sizes, WordPress works a little bit different. You can specify the maximum width and height, and the system will scale down the image according to those settings, so it doesn’t get cropped. These are usually images that you will use inside posts and pages.

Why is WordPress generating additional sizes?

If WordPress didn’t generate additional image sizes, you would have to create ones manually. The alternative would be having the same image size throughout your site or designers would have to work much harder to set the dimensions of each and every image through the code. This option would also make it much more difficult to customize.

Imagine how much time would you need to open every file in a photo editor, set a custom dimension, and then upload it to WordPress?

Do you know that WordPress themes can use the same image in several different dimensions depending on the location? That would mean generating several image files every time that you’re about to upload a new image! No one would have time for that.

Change featured image size

Obviously, not all WordPress themes use the same featured image size. So, when switching between themes or simply when you want to modify one to your needs and likings, you might want to adjust the featured image size.

Change featured image size in WordPress

Maybe a smaller size will look better an accentuate the title? Maybe you want your featured image to be wider? Luckily, whatever the reason for changing the featured image size, you won’t have to code anything on your own. We are about to show you a fantastic free plugin that will help you.

Check your theme settings

Before installing any additional plugins, you should thoroughly check your theme settings. In the last few years, theme developers have been allowing modifications of many theme features. So, depending on a theme that you have, there is a chance for finding a featured image size option right in the theme settings.

Go to Appearance -> Themes -> Customize and look for the options. Also, some themes will have additional settings that can usually be found in the Appearance menu. If you can find one, you’re in luck because you can change the featured image size in just a few clicks. If not, don’t worry; the following plugin will still be more than simple enough to make the necessary changes.

Simple Image Sizes


Simple Image Sizes

When you install Simple Image Sizes, the basic media settings that we just talked about will instantly get expanded. The plugin will recognize all other image sizes from the currently active theme, and it will also allow you to create custom sizes on your own.

Once you have activated the plugin, please navigate to Settings -> Media. Among all additional image sizes, you should find the one that’s dedicated to the featured image. If you are using a standard Twenty Seventeen theme, you should find the “twentyseventeen-featured-image size” option. Here you can easily set a custom width and height for featured images.

Depending on a theme that you’re using, there might be more than just one featured image size. For example, a theme might show featured image on the front page, single posts and some widgets as well. In that case, three sizes would be needed to make the best out of the feature. Depending on how you want to personalize the featured image, change settings accordingly. Don’t forget to hit the update button, save changes and open your site to see what happened to the pictures.

What about the older images?

Usually, when changing image dimensions, WordPress makes changes just to the new ones that you are about to upload. But what about the old ones that you are already using?

Thumbnail Regeneration

Luckily, the developer of Simple Images Size was kind enough to introduce a feature that will fix this problem. On the same Media Settings page, just scroll down through the list of image dimensions. You will find a Thumbnail Regeneration feature that lets you select which thumbnails you want to rebuild. Since we’re talking only about featured images, select the same thumbnails that you edited earlier (“twentyseventeen-featured-image” size thumbnail for Twenty Seventeen theme).

If you want even more control over thumbnails, scroll a little bit more and select a post type on which you want to rebuild.

Once you’re ready, click if you want to regenerate thumbnails, and don’t forget to save changes.

Downsides of changing image sizes

While setting up the new image dimensions is quite easy with Simple Image Sizes, be careful when modifying your pictures.

If you are working on a smaller site that still doesn’t have that many photos, you can relax and regenerate the thumbnails. But note that there are sites with hundred thousands of images.

Generating a new dimension for each image may take a lot of space on your server. So before confirming the change, be sure that you know what you’re doing.

Also, WordPress doesn’t really take care of your old thumbnails. So, even if you’re not using them anymore, all those images will still sit down in the folder and take up precious hard drive space. Some image cleanup plugins can help you if you’re running a smaller site. But for larger websites with tons of photos, you will need a more professional (and unfortunately more complicated and more expensive) approach.

Wrapping up

Featured images are probably the most important media file type that you will have on your blog. Because of that, it is crucial that they look good. While having a beautiful photo or a nicely generated computer image is important, you should also take care of the featured image size.

Luckily, you don’t have to be a developer or have a complete understanding of how WordPress processes images. You just a need a simple plugin that will help you set new featured image sizes and, at the same time, rebuild the old photos that you have been using for months or maybe even years.


This guide is an introduction to mastering the art of blogging. It provides easy to follow steps to start, maintain, and grow your blog.

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