Whenever we upload an image on WordPress media library, it generates additional copies of that image with different dimensions. It helps in creating an optimized version of a website as one can load small size copy of the same image in case of loading a thumb is required. By default it generates 3 different sizes as thumbnail, medium and large for an uploaded image. Now if you want to change the default value of these sizes, the option is available on settings page but it will not change the dimension of already uploaded images. You need to either create a copy of the images manually or regenerate the thumbnails for older uploads by following the below steps.
First of all, if you want to change the default dimension of the image, follow these steps,
To change the Thumbnail Image size for future uploads:
Step 1 : Go to your WordPress Dashboard => head over to the Settings section => click on Media menu => you will see a window of Media Settings as shown below :
Step 2 : In Media Settings window, customize the thumbnail size & Save Changes.
Above steps will set a new dimension for auto generated media files in WordPress. Now it is time to regenerate the thumbnails with new dimension for the older uploads. Follow the steps below,
To apply modified thumbnail image size to previous uploads :
To achieve this, you can use Force Regenerate Thumbnails plugin. It allows you to delete all old images size and REALLY regenerate the thumbnails for your image attachments. Follow the below guidelines for the same :
Step 3 : Go to your WordPress Dashboard => head over to the Plugins section => click on Add new menu => you will see a window of Install Plugins.
Step 4 : Search for “Force Regenerate Thumbnails” or download the plugin from this page.
Step 5 : Click on Install.
Step 6 : Activate the Regenerate Thumbnails Plugin.
Step 7 : Go to your WordPress Dashboard => head over to the Tools section => click on Force Regenerate Thumbnails menu => you will see a window of Force Regenerate Thumbnails => Click on Regenerate All Thumbnails. A window will appear regenerating the thumbnails as shown below :
It will take some time to regenerate the thumbnails.
You can also resize selected images simultaneously with the help of Force Regenerate Thumbnails plugin. To achieve this, follow the guidelines as below :
Step 1 : Go to your WordPress Dashboard => head over to the Media section => click on Library menu => you will see a window of Media Library as shown below :
Step 2 : Tick the ckeckboxes of the images which you want to resize to thumbnail size.
Step 3 : Under Bulk Options, select Force Regenerate Thumbnails.
To achieve similar results, you can also use another free plugin named Regenerate Thumbnails. It can generate thumbnails in bulk without deleting the older ones to avoid any image URL break (if hard coded URL used).
Did you find this article helpful? Share your thoughts about such scenario where you unintentionally deleted all your older thumbnail images and recovered the same using such plugin.