TimThumb or WP Post Thumbnails

  First Steps

Also explained in this video.


  • Images are resized on-the-fly
  • Can resize images not uploaded with WordPress media uploader
  • Does not create multiple images on your server (storage)
  • Uses cached image(s)- some users prefer this rather than having to load same image in multiple sizes on a page
  • Easier to change width & height of an image (works out-of-the-box in most themes without any setup required)
  • Does require ability to write cache images on server (folder permissions)

WP Post Thumbnails

  • Image sizes have to be pre-defined in theme
  • A new image file is created and stored on upload to your server (if you have server storage limits, this is not ideal). 1 image can result in many images on server.
  • If you ever want to change an image size, you’ll have to regenerate thumbnails for all previous posts.
  • If you have existing posts, they will need to have thumbnails generated otherwise site will not have images in required sizes
  • If you switch themes, it’s likely that the images will not be sized perfectly for the next theme