How to Regenerate Thumbnails in WordPress

When you switch to a new theme, the featured images that you have used in the previous theme may not appear as desired. As a result, your blog posts look ugly and unprofessional.

Each theme has a different image ratio and dimension for the thumbnail images. By default, when you upload an image to WordPress, it creates different sizes images defined in the theme and saves them in the uploads folder. The new image sizes are only applied to the images you upload after activating the theme.

Therefore, when you switch to a new theme, the previously uploaded thumbnails images display inaccurately on your website.

To tackle this situation, you need to regenerate the new sizes for all previously uploaded images. This process is commonly known as regenerating thumbnails.

In this article, you will learn how you can regenerate thumbnails in WordPress so that your website’s images look professional without any distortion.

An Overview of WordPress Thumbnail Images

When you upload an image to WordPress, it automatically resizes it using three sets of default dimensions: Thumbnail size, Medium size, and Large size.

The default sizes for Thumbnail, Medium and Large size are 150x150px, 300x300px and 1024x1024px respectively. You can change these default sizes by navigating to Settings > Media from your dashboard.

Default Image sizes in WordPress

You can use these image sizes within your posts and pages.

Using defined image sizes in Post

It works perfectly. But, the problem comes when you switch to a theme that uses a different set of default dimensions. Once you activate the new theme, all the new uploads will use the updated set of dimensions. However, all your previous uploaded images will remain incorrectly sized and display distorted on your site. Those outdated thumbnails will look inappropriate and unprofessional to your readers.

To solve this problem, you must regenerate new sizes for all previously uploaded images.

Thankfully, there is a free plugin called Regenerate Thumbnails that automatically regenerate thumbnails for all your images. Using this plugin, you can also regenerate thumbnails for an individual image or selected images in a single click.

How to Regenerate Thumbnail Images in WordPress

Regenerate Thumbnails is far most the best plugin to generate new thumbnail image sizes on your WordPress site. Let’s take a look at how to do it.

Step 1: Install and Activate the Regenerate Thumbnails plugin

Regenerate Thumbnails is available in the WordPress repository. So, you can download it directly from your dashboard.

To install the plugin, navigate to Plugins > Add New > Search for “regenerate thumbnails”. Once you see it in the search result, click on Install Now and then on the Activate button.

Installing Regenerate Thumbnails plugin

Step 2: Regenerate Your Thumbnail Images

Once the plugin is activated, you can access the plugin by navigating to Tools > Regenerate Thumbnails.

Before you start regenerating thumbnail images, let’s have a look at the options that it offers. There are two options that you can choose before you begin using this plugin.

Regenerate Thumbnails settings

The first one enables the plugin to skip regenerating the images that are already correctly-sized. You should always keep this enabled as it saves time.

The other option is for whether you want to delete thumbnails for old image sizes. With this setting enabled, you will free up some space on your server as you no longer need those old images. As you will be regenerating all your images, I recommend keeping this setting enabled.

Now, to generate thumbnails, click on the Regenerate Thumbnails button. It will start regenerating thumbnails for all your images to match the dimensions of your new theme.

Regenerate Thumbnails Progress status

Depending upon the number of media files to regenerate and your web server’s performance, it will take a while. You will see the progress bar as it proceeds.

When it is finished, you will see a success message that informs about the total time taken, the number of images that have been successfully regenerated as well as the number of failures.

How to Regenerate Thumbnails for Specific Images

If you want to regenerate thumbnails for a single image or selected images, you can also do that using this plugin.

First, navigate to Media > Library from your WordPress dashboard. Then, move your mouse cursor over the image which you want to regenerate. You will notice a new option, “Regenerate Thumbnails”.

Regenerate Thumbnails for Specific Image

When you click on it, you will get the same settings as mentioned earlier.

Regenerate Thumbnails for a single image

You can also select multiple images and regenerate them in bulk, as shown in the screenshot below:

Regenerate Thumbnails in bulk

Regenerating images doesn’t affect your original upload. It creates additional copies of images in the newly defined sizes for correct display on your website.

It also does not delete previously uploaded image sizes. You can delete them if you are sure that you haven’t used those sizes anywhere on your website.

If your image dimension is less than the newly defined sizes, the plugin won’t generate any new copies of images.

Final Thoughts

I hope this article helped you learn how to regenerate thumbnail images on your WordPress site. It is recommended that you always run this plugin after you switch to a new theme. It will solve the image distortion issues and improves user experience.

If you found this article helpful, you can check this article to Lazy Load WordPress Images and Videos.

Have you ever run into troubles while regenerating thumbnails on your website? Do you know any other methods to regenerate thumbnails? If you have any queries or feedback, please feel free to let me know in the comments below.

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