Well that completely depends on their age. I had six babies from birth and their weights were similar but a few were different. I have weight charts on all of them for the first two years of their lives. It's not quite done on a monthly basis but you will get the gist.
This is the runt of the litter:
Flame-1.jpg - Image - Photobucket - Video and Image Hosting
And the biggest of the litter:
Spencersweight.jpg - Image - Photobucket - Video and Image Hosting
This one is a girl from the same litter, the first two are boys. Presley is your 'average' size gpig:
Presleysweight.jpg - Image - Photobucket - Video and Image Hosting
But as I said it completely depends on the pig.