Let me see if I can paint a picture... you have two measuring cups, side by side. In one, you have 8 ounces of water. In the other, you have 8 ounces of feathers. Both are equal in volume. But, in weight, they are VERY different. Apply this to candle wax, FO, etc. 8 ounces in volume is NOT equal to 8 ounces in weight. This is what we mean when we say that 1/2 oz of FO, by volume, isn't the same as 1/2 FO by weight. Or as Stella said, 8 ounces of wax. As far as what Grama said, when you freeze water, it expands. The chemical changes something goes through when it changes from one state to another (solid to liquid, liquid to solid, etc) change things a bit. So, if you melt 16 ounces, by weight, of wax you get 20 ounces, by volume, of melted wax. (I'm not sure if soy wax gives you 20 ounces, by volume. I'm just using this as an example). Did that help or simply make it worse?