1 lb of solid wax still weighs 1 lb when its melted. The difference is the volume--the amount of space melted wax takes up in the pour pot. The volume of 1 lb of melted wax is approximately 20 fluid oz. Fluid oz denotes volume Oz denotes weight Example: 200 lbs of bricks weighs the same as 200 lbs of feathers, BUT the volume is quite different. 200 lbs of bricks take up about 1/2 pallet, however 200 lbs of feathers will probably fill a small warehouse. Do you see the difference? While its good to know the volume of melted wax, the weight is still the same. You base your measurements of FO on weight not volume. HTH.