Legacy ImageMagick Discussions Archive

Generally you can only know the image file size by writing it to memory or disk first. Some formats are predicatable in size based on the image width and height but generally this is not reliable for most image formats.

You want to write to a blob to measure the image size in memory. MagickWand has a MagickWriteImageBlob() method. There may be a similar method in MagickWand for PHP.