After changing wordpress theme, the old posts of your starts showing different thumbnail dimensions. This is because your new theme uses different thumbnail dimensions than your previous theme. New thumbnail dimensions applies only to images you upload after new theme activation. This same thing also happens when you change any of your thumbnail dimensions from “Settings -> Media.”
While facing this situation you might have tried things like changing the thumbnail dimensions from the Settings page. But sadly nothing worked for you to overcome this situation. The solution to this situation is to regenerate your old thumbnails according to new dimensions.
For wordpress users this becomes easy using the “Regenerate Thumbnails Plugin.” Using this plugin you can regenerate thumbnails of all image uploads, individual image uploads, or even specific image uploads.
Steps to Regenerate Thumbnails
Regenerate all thumbnails uploaded on your blog
- Install and activate the “Regenerate Thumbnail” plugin.
- Now goto Tools–>Regen. Thumbnails
- Here you will find button labeled “Regenerate All Thumbnails.”
- Pressing this button will regenerate all the thumbnails uploaded on your blog according to dimension defined in Settings –> Media page.
Regenerate thumbnail for individual or multiple image uploads
- Goto Media –> Library
- Hover over the an image’s row and you will find Regenerate Thumbnail as an option for individual uploads.
- Also you can select specific multiple images using the checkboxes and Regenerate them from “Bulk Actions” dropdown box above.
Note: The “Bulk Actions” dropdown option is available for WordPress 3.1 and above only.
“Regenerate Thumbnail” plugin does not modify your original images or deletes your old thumbnails. It just creates another copy of thumbnail according to size defined in the Settings –> Media page. This plugin is also helpful if your theme has featured post with thumbnail.