WordPress automatically creates multiple versions of every uploaded image. These versions, commonly called thumbnails, are used throughout your website to display images in different sizes.
If you change your theme, modify image size settings, or update how images are displayed on your website, existing thumbnails may need to be regenerated.
Table of Contents
How WordPress Handles Images
Whenever you upload an image, WordPress automatically creates several resized versions.
You can view the default image size settings by navigating to:
Settings → Media
By default, WordPress generates:
| Size | Default Dimensions |
|---|---|
| Thumbnail | 150 × 150 px |
| Medium | 300 × 300 px |
| Large | 1024 × 1024 px |
Depending on your theme, additional image sizes may also be generated automatically.
Important
Changing image size settings affects only newly uploaded images.
Images that were uploaded before the change will keep their old thumbnail sizes until they are regenerated.
Changing Image Sizes
Step 1
Navigate to:
Settings → Media
Step 2
Modify the dimensions for:
- Thumbnail Size
- Medium Size
- Large Size
Step 3
If you want square thumbnails regardless of the original image proportions, enable:
Crop thumbnail to exact dimensions
Step 4
Click:
Save Changes
Editing Images in the Media Library
Individual images can also be edited directly from the Media Library.
Step 1
Navigate to:
Media → Library
Step 2
Select the image you want to edit.
Step 3
Click:
Edit Image
Available Options
You can:
- Crop images
- Resize images
- Rotate images
- Scale images
- Adjust thumbnail settings
Applying Changes
After making your edits, click:
Save
to apply the modifications.
Using WordPress Media Settings
If you want all future uploads to use different dimensions:
Step 1
Navigate to:
Settings → Media
Step 2
Specify new values for:
- Thumbnail Width and Height
- Medium Width and Height
- Large Width and Height
Step 3
Optionally enable:
Organize my uploads into month- and year-based folders
Step 4
Click:
Save Changes
Using the Regenerate Thumbnails Plugin
Installing the Plugin
Step 1
Navigate to:
Plugins → Add New
Step 2
Search for:
Regenerate Thumbnails
Step 3
Click:
Install Now
Step 4
After installation, click:
Activate
Regenerating Existing Thumbnails
Step 1
Navigate to:
Tools → Regenerate Thumbnails
Step 2
Review the available options.
Skip Regenerating Existing Correctly Sized Thumbnails
This option is enabled by default.
- Enabled: Only missing or incorrectly sized thumbnails are regenerated.
- Disabled: All thumbnails are regenerated.
For most websites, leaving this option enabled is recommended because it reduces server load.
Delete Thumbnail Files for Old, Unregistered Sizes
This option removes thumbnail files that are no longer used.
Benefits:
- Frees up disk space
- Removes obsolete image sizes
Warning
Before enabling this option, make sure old thumbnails are no longer being used by your website.
If an old thumbnail is still referenced by your theme, plugin, or content, it may stop displaying correctly after deletion.
Update Post Content to Use New Sizes
If available, this option updates image references inside posts and pages to use the newly generated image sizes.
Step 3
Click:
Regenerate Thumbnail, Medium, Large Image File Sizes
or the equivalent regeneration button displayed by the plugin.
Step 4
Wait for the process to complete.
The duration depends on:
- Number of uploaded images
- Server performance
- Number of generated image sizes
Large websites may require several minutes.
Completion Message
Once the process finishes, you should see:
All Done
When Should You Regenerate Thumbnails?
Thumbnail regeneration is recommended when:
- Changing WordPress themes
- Updating image dimensions
- Installing a theme that creates custom image sizes
- Removing unused image sizes
- Fixing incorrectly displayed images
- Migrating a website
Summary
To regenerate thumbnails in WordPress:
- Adjust image dimensions under:
Settings → Media
- Install and activate the Regenerate Thumbnails plugin.
- Navigate to:
Tools → Regenerate Thumbnails
- Choose the desired options.
- Start the regeneration process and wait for completion.
Regenerating thumbnails ensures that all existing images match your current theme and media settings, helping maintain a consistent appearance across your website.