File Size
Athough you have the same measurement of image, but saving in different file formats will have different file size. For example, a 500 X 500 pixels in JPG format will be only 10 KB, but the file size maybe 1 MB and above if you saved them in PSD or TIF format.

Not just the sharpness & clearness we have to think about when saving files,  In some cases, we also need to think about the
file size, especially when sending emails or building webpages.

Let's try out our self, first get a image or picture from your pc, then save them in different file formats. After that compare the file size.

File > Open (choose the zebra image):
select the zebra image and click the open button.
As you can see, the image is in PSD file format:
Then File > Save AS:
After saving in all formats, click on the button to see the [Details].