I am developing a theme which uses different image sizes. So I will be adding 7 image sizes, are they too many? Could that break anything like the image size selector, other parts of the interface or upload performance?

Also, is it a bad practice to remove the default image sizes from the theme for example adding following to the theme?

unset( $sizes['thumbnail']);
unset( $sizes['medium']);
  • Simply set the default sizes to 0 in the settings. This skips those built in sizes. So no need to use unset(), which is not a good idea.
    – kaiser
    Commented Feb 26, 2013 at 12:43
  • @kaiser Thanks. I'm trying to use your plugin but having trouble with it. I posted question about that, could you please have a look at that? Here: wordpress.stackexchange.com/questions/88442/…
    – jay
    Commented Feb 26, 2013 at 13:05
  • Seen it - done that.
    – kaiser
    Commented Feb 26, 2013 at 14:18

2 Answers 2


For each image size, WordPress creates unique image on image upload. Than, when you register 7 image sizes, and upload single image, 8 unique images will appear in your wp-content/uploads directory. Is this too much for small blog with 100 posts to have 800 images on the server? But having 1000 posts? It depends.

Another point of view - page load speed. When displaying another page of your site, seeing the same image but in new different size (thus no cached in my browser), I have to download that image again and that makes page loading slower and user experience poorer.

When you remove default sizes, I guess that after chaning theme from yours super cool one to another even more super cool one, user will have to recreate all thumbnials in order to have thumbnails on default size available again. This might not be an issue, there are plugins for that, but again, when having 1000 images on my site, this task would be really resource demanding.

  • Thanks for the answer. Exactly thats what I think too, that too many copies of an image will add additional load on server, thats why I asked this question. If I try to resize the large image into smaller size with CSS, it looks like stretched. Is there any alternative for that (eg. any plugin etc? )
    – jay
    Commented Feb 26, 2013 at 9:18
  • Maybe you can give binarymoon.co.uk/projects/timthumb a try, but still, its creating images on the server and user has to download all them. So This wouldn't be a ideal solution neither. Commented Feb 26, 2013 at 9:20
  • 1
    OMG, not TimThumb :( - Kaiser and Bueltge have alternatives that work within WP standards: Dynamic Image Resize and WordPress Image Resizer.
    – brasofilo
    Commented Feb 26, 2013 at 9:22
  • Doesn't the Timthumb do exactly same thing? It creates an additional size and uploads on the server?
    – jay
    Commented Feb 26, 2013 at 9:22
  • 1
    I disagree with this, loading the proper size is way more effective for page speed than caching and re-sizing images via HTML or CSS, it does not even compare.
    – Wyck
    Commented Feb 26, 2013 at 20:17

The only downside to adding lots of images is space and upload CPU use. In most every case storage space is cheap, especially since the images are smushed.

The initial CPU load will be heavier when the image is uploaded and processed so take that into consideration, typically this is a fraction of your servers time and inconsequential.

The upside is that you load the proper size, and that far out-ways bad practice of re-sizing via CSS or HTML which you should never do. Also with proper sizing your output exactly what you want.

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