Homemade Liquid Laundry Detergent Recipe

I know that this blog is dedicated to bath and body products, but since I share recipe on how to make your own soap this recipe for liquid laundry detergent qualifies to be shared.  This recipe for Homemade Liquid Laundry Detergent originally appears on the Fan of Stuff, but I found it through a site I follow called Totally Tutorials.  It seems like a very simple recipe - only 3 ingredients, but I find it confusing about how much soap you need.  It calls for 1/2 bar of grated soap, but what is the originally weight of the bar of soap?  4 oz?  The picture looks deceiving.  If anyone out there knows, please share. I would be interested to know so that I can try this recipe.