When calculating recipe and portion costs, allowances need to be made for unavoidable waste when calculating the recipe yield. Failure to do so will result in understating portion costs. Subsequently, instead of figuring on 100% yield from a recipe, assume that only 98% will be actually used, allowing 2% for evaporation, over portioning and quality control waste. This percentage of waste will differ depending on the menu item. There is a higher allowance for waste on items prepared from scratch than on items that are purchased pre portioned. For example, if steaks are purchased pre cut, there would be zero tolerance for waste and over portioning. However, if steaks were cut in house, the yield (number of steaks) from a primal cut of meat will vary depending on the weight of the primal cut and the skill of the butcher. Once the steaks are cut and sent to the kitchen for sale, however, there would be zero tolerance for waste or quality control. Furthermore, yield calculations are most critical for more expensive items, such as meats, since these have a more dramatic impact on cost and profit outcomes.
Mutkoski, S. A., & Schurer, M. L. (1981). Meat and fish management. North Scituate, MA: Breton.