When to use Resize Image in Pixels
Resize any photo to exact pixel dimensions. Check the resize image dimensions you need, lock the aspect ratio, and optionally keep the file under a size limit in KB.
The best image settings depend on where the picture will be used. Pixel dimensions describe width and height; file size describes bytes. Changing one does not guarantee a particular value for the other. Keep the original, compare the result at its intended size, and choose a format accepted by the destination.