Hi Robert, I'm not sure if you are referring to file size or pixel width.
One easy way to find this out the file size is to browse to the page in Internet Explorer, then click on File >> Save As.
Save the page to your desktop. It will also create and save a folder of images for that page to your desktop.
You can get your page's total file size by adding the file size of the html file on your desktop to the size of the folder of images IE created for you. (right click on them)
Another great source is:
http://www.echoecho.com/They have a form on the homepage that will let you check file sizes of pages, broken links, spelling errors, invalid HTML ect.
Also a great source for user stats!