Responsive Image Module not reducing the file size when resizing the browser (Drupal 8) I have an issue using Responsive Image Module for drupal 8 that I can't seem to solved or figure out. As shown in this screenshot the file size of the original image is 685kb. But once I started to resize to the first breakpoint which is around 1366px the file size jumps to 1023kb or 1mb. My expectations was the file size should be reduced to even smaller size. I tried the option Resize and setting different dimensions proportionally or even Scale. But I still get the same results
I guess the 685kB is your original, uploaded file and the 1MB file is generated on the webserver by GD or ImageMagick.

When your original file is heavily compressed and at the same time your JPG quality setting is very high, the generated (pixel-smaller) files can be (byte-wise) larger than your original. There is not much you can do against this except reducing JPG quality settings in Configuration &gt; Media &gt; Image Toolkit

Another option would be using a modified JPG library like MozJpeg, but this is beyond the scope of Drupal.