Hi Sabrina! The yield is actually how many yards of wick it takes to weigh out to 1 pound. So, for the LX21, it takes 352 yards of wick to equal 1 pound. The ROC (rate of consumption) tells you how many oz. per hour that the wick burns up. I have read on Atkins & Pearce's website that their wicks are all tested in straight paraffin wax without additives so, if you add additives (FO, Steric, etc.), it doesn't really help that much because you are using a different type of fuel. I think the ROC does give you a good idea of a starting point and wicks in different families with similar burn rates. HTH, Kim