Yield: what a kilo actually costs on the plate
If you cost a dish using the price you paid per kilo, the number is wrong. It is wrong in the same direction every time and usually by more than people expect, because you do not serve what you buy. You serve what survives trimming, boning, peeling and cooking.
Yield is the usable weight divided by the weight you paid for. Buy a 4 kg whole fish, fillet it, and you might have 1.8 kg of skin-on fillet — a 45% yield, which means the real cost of that fillet is the purchase price divided by 0.45. If the fish came in at 40 a kilo, the fillet costs you about 89 a kilo. Cost the dish at 40 and every portion is quietly losing money. The same applies to a striploin that needs its fat cap and side chain off, to leeks where you use the white, to anything that gets peeled.
A yield test only needs doing once per item, then revisiting when the supplier or spec changes. Weigh it as it arrives, break it down the way you really do in service rather than slowly for the test, weigh the usable product and the trim separately, and divide. Doing it the way you really work matters, because a yield measured by someone taking twice the usual care is not the yield you will get on a Friday.
Cooking loss sits on top of that. A hard roast can take 20 to 30% of the weight, and a braise still shrinks the portion even if less of it ends up on the tray. If the menu promises 200 g on the plate, you are not cutting 200 g raw. Both losses have to be in the costing or the number is fiction.
The other half of the picture is that trim is not worthless, and counting it as pure loss overstates your cost. Bones and frames become stock, meat trim becomes staff meal or a braise, vegetable offcuts go to soup. None of it is free, because it all takes labour, but none of it is zero either. The kitchens that handle this well are the ones where the yield test and the specials board are the same conversation.
