I usually send 8x10 photos and have never seen it weigh over 2 oz (approximately 57 grams). It depends, of course, on the type of envelope you use and what else you put in the package. The post office should be able to help you out too.
If you're just looking for a conversion, use [url=http://www.google.com/search?btnG=1&pws=0&q=56+grams+in+ounces]Google[/url]... just type the conversion in.

I'd say take it to the post office and have them weight it. they can give the exact amount of weight. {up}

RYAN-J 8)

hey guys im wanting to send 2x 6x8 photos to cody simpson i am from australia and i know that shipping costs 98 cents per oz but i dont know how to calculate with oz only grams how much do you think 2 6x8 photos in my sase will weigh do you think it will be more then 25 grams please some one help !!! :)