Hello friends,

Ever wondered if it is possible to change the different image sizes in WordPress without having problems with the generated thumbnails after that?

Then I have to calm you down as this is possible and it is also extremely easy to achieve.

All you have to do is install and activate the Regenerate thumbnails WordPress plugin and with just one click (yes, one) all your thumbnails will be fixed, according to the new sizes that you have set up for the different images.

Why is this plugin necessary?

Let’s assume that you have decided to add a new theme and it requires you to have different sizes for your image thumbnails. And before I continue with this post I have to clarify that a “thumbnail” for WordPress is the generated image with a specific size (set under Settings – Media). There you have (by default) a thumbnail size (for the smallest image), medium and large sizes.

Each of these three are considered thumbnails. Why? Because when you upload an image to the WordPress media library, the system creates different thumbnails based on these three default sizes so that you can insert them into your posts or pages or custom content types.

The original image size is not altered – only these new files (the thumbnails) are created and used.

So if you go to Settings – Media and change some of them and then click on the “Save changes” button then the next image that you upload to your WordPress media library will be accompanied by its respective thumbnails with their new image sizes.

However your already uploaded images will continue to use the old thumbnail sizes and that is not desired. You have to either re-upload them (something that is absolutely not acceptable unless we are speaking for a couple of images) or to use a high-quality solution that will regenerate these files once again and apply the new sizes correctly. Such solution is the Regenerate Thumbnails WordPress plugin.

How to use it?

As usual search for it in wordpress.org or add it via the “Add New” plugin section in your WordPress dashboard. Then activate Regenerate Thumbnails.

After this head to Settings – Media and apply the desired image sizes for the three default image thumbnails and save these changes.

Next head to Tools – Regen. Thumbnails

This is the primary place to use the plugin. In this section you are provided with some simple explanation why you need to use it and when. Regenerate Thumbnails also reminds you of the possibility to generate new thumbnails for each file individually by going to the WordPress Media Library. There will be a new link for each image and when clicked upon only its thumbnails will get regenerated – nothing else. This is quite handy for future changes that are not that drastic (for example only a specific image should have thumbnails with different sizes). It also saves time and load on your server.

But this is the optional usage. We are still on the Tools – Regen. Thumbnails section in your WordPress dashboard and we want to regenerate ALL thumbnails.

So now you need to click on the big “Regenerate All Thumbnails” button and sit back and relax. The process could take some time but in the end your images will be displayed correctly once again.

And if something goes wrong?

Usually I have no such experience with this plugin. But in case your hosting server gets too loaded or something else occurs, all you have to do is to apply the regeneration process individually by going to your Media library and locating the specific image/images (as described above).

So this is it friends!

Happy thumbnail regeneration and see you soon!

PS: Don’t forget to share your thoughts on this wonderful plugin.