What is yield, and how to measure it

A chef costs a salmon dish from the price on the invoice: 15.00 a kilo, 180 grams a portion, so 2.70 of fish on each plate. The dish is priced to make a healthy margin. But the salmon arrives whole, and by the time it is scaled, filleted, skinned and trimmed, only about six of every ten kilos bought end up on a plate. The real cost of the fish on each plate is not 2.70 but 4.50, and the healthy margin has quietly disappeared.

What is yield? In a kitchen, yield is the usable part of an ingredient as a share of what was bought: the fillet from the whole fish, the peeled carrot from the bag, the cooked meat from the raw joint. It is one of the most important numbers in costing, and one of the most often ignored, because the invoice shows the price of what was bought, not the price of what was used.

This guide covers what yield is, the kinds that matter in a kitchen, how to run a yield test in twenty minutes, how yield changes the real cost of a dish, how to reduce prep waste and how to keep yields current. Every venue and figure in it is an example.

Yield is the weight, or quantity, of usable product divided by the weight bought, usually expressed as a percentage. If a five-kilo box of carrots gives four kilos of peeled, trimmed carrot, its yield is 80 per cent.

The usable part is what goes into the dish. The rest, the peel, the tops, the trimmings, the bones, the fat, is either waste or a by-product used elsewhere, such as bones for a stock.

Yield matters because the kitchen pays for everything it buys, but sells only what it uses. An ingredient with a low yield costs far more per usable kilo than its invoice price suggests, and a costing that ignores yield understates the cost of every dish that uses it.

The effect is largest on the most expensive ingredients: whole fish, meat on the bone, shellfish and some vegetables with heavy trimming. A few per cent of yield on a costly protein can decide whether a dish makes money.

There are a few kinds of yield in a kitchen. Trim yield is the usable part after peeling, trimming or cleaning. Butchery yield is the usable part after breaking down a carcass, a joint or a whole fish. Cooking yield is the weight after cooking, because most food loses water as it cooks. Recipe yield is the number of portions a recipe produces.

Each one affects the cost per portion, and a dish may involve several: a joint of beef has a butchery yield when it is trimmed and a cooking yield when it is roasted.

Butchery yield is the share of a whole piece of meat or fish that becomes usable portions. A whole salmon gives fillets, and leaves the head, bones, skin and trim; a whole lamb loin gives cutlets and leaves bones and fat. The butcher's skill, and the kitchen's, decides how much of the piece is used.

Measure butchery yield for every cut the kitchen breaks down itself, and compare it with buying the cut ready prepared. Sometimes buying whole is cheaper even after the yield; sometimes the prepared cut is the better deal.

Cooking yield is the weight of food after cooking as a share of its raw weight. A joint of beef weighing three kilos raw may weigh about two kilos once roasted, because it has lost water and fat. Rice and pasta go the other way, gaining weight as they absorb water.

Cooking yield matters whenever portions are weighed after cooking. A recipe that portions 150 grams of cooked meat needs more than 150 grams of raw meat, and the costing must use the raw weight.

Recipe yield is the number of portions a recipe makes. A sauce made from a set of ingredients might yield forty portions; a stock might yield ten litres. Knowing the recipe yield turns the cost of the batch into the cost of each portion.

Measure it, rather than assuming it. A recipe that was meant to yield forty portions but yields thirty-two, because of reduction or over-portioning, costs a quarter more per portion than the costing says.

A yield test measures yield in the kitchen. It takes about twenty minutes for most ingredients. First, weigh the ingredient as it arrives, before any preparation. Second, prepare it exactly as the kitchen normally does: peel, trim, fillet or butcher. Third, weigh the usable product. Fourth, weigh the trimmings, and note what can be used elsewhere.

Divide the usable weight by the starting weight, and the result is the yield. Write down who did the test, how and when.

One test is a start, but yields vary: between deliveries, between suppliers, between seasons and between cooks. Repeat the test three times, ideally with different deliveries and different cooks, and use the average.

Where the results vary widely, look at why. A yield that depends heavily on who does the trimming is a training issue as much as a costing one.

A five-kilo box of carrots costs 6.00, or 1.20 a kilo as bought. After peeling and trimming, the kitchen has 4.1 kilos of usable carrot: a yield of 82 per cent. The real cost of usable carrot is 6.00 divided by 4.1, or about 1.46 a kilo.

For a cheap vegetable, the difference is small per portion. Across every dish that uses carrots, every week, it is not.

A whole salmon weighing 4.0 kilos costs 60.00, or 15.00 a kilo. After scaling, filleting, skinning and trimming, the kitchen has 2.4 kilos of usable fillet: a yield of 60 per cent. The real cost of usable fillet is 60.00 divided by 2.4, or 25.00 a kilo.

A 180-gram portion therefore costs 4.50 of fish, not the 2.70 the invoice price suggests. The difference, 1.80 a plate, is the gap between a dish that earns and one that does not.

Use the usable cost, not the purchase price, in every recipe costing. The usable cost is the purchase price divided by the yield. For the salmon, 15.00 a kilo divided by a yield of 60 per cent is 25.00 a kilo.

Our guide to recipe costing: one dish from box price to plate covers the whole method. Yield is the step most often missed.

A kitchen whose costings ignore yield will see an actual food cost higher than its theoretical one every month, and may blame waste or theft for a gap that is really yield. Our guide to what food cost is, and which one you mean covers the difference between the two.

Put the yields into the costings, and the theoretical food cost moves closer to reality. The gap that remains is the one worth investigating.

Prep waste is the part of the trimmings that cannot be used: the peel, the inedible parts, the damaged pieces. Some prep waste is unavoidable, but much can be reduced by better trimming, better ingredients or using trimmings elsewhere.

Our guide to how to reduce food waste in a restaurant kitchen covers the wider methods. Measuring yield is the first step, because it shows how much waste each ingredient creates.

Trimmings are not always waste. Fish bones make stock, vegetable trimmings make stock or staff meals, the ends of a joint make a sauce or a terrine. Each use turns part of the trimmings into something the kitchen would otherwise have to buy.

Record which trimmings are used, and how. A by-product that replaces a purchased ingredient effectively raises the yield of the original.

Yields differ between suppliers. One supplier's fish may be better handled, with less damage and trimming; one supplier's vegetables may be fresher, with less spoilage. A cheaper price with a lower yield can cost more per usable kilo.

Compare suppliers on the usable cost, not the invoice price. A yield test on a sample from each is the fairest comparison.

Yields change through the year. Vegetables at the end of their season may need more trimming; fish at certain times of year may yield differently. A yield measured in spring may not hold in autumn.

Repeat the tests for the key ingredients a few times a year, and update the costings when the yields change.

Yield depends on skill. A cook who trims carefully gets more usable product from the same box than one who trims in a hurry. Training the team to trim, fillet and portion well raises the kitchen's yields directly.

Show the team their own yield results. A cook who sees that their salmon yield is five per cent below a colleague's has a clear and fair reason to learn from them.

Keep a record of every yield tested: the ingredient, the supplier, the date, the starting weight, the usable weight, the yield and who did the test. A simple sheet or spreadsheet is enough.

Use the recorded yields in every costing, and update them when new tests show a change. A yield that lives in one chef's memory is lost when that chef leaves.

Not every ingredient needs a yield test. Start with the ones that cost most, that the kitchen prepares itself and that are used in the most dishes: whole fish and meat, expensive vegetables, shellfish, fruit with heavy peeling.

A short list of ten or fifteen key ingredients, tested and recorded, covers most of the kitchen's yield risk.

Yield affects the stock count too. A count of whole fish in the cold room values the fish at its purchase price, but the kitchen will use only part of it. The count is still right, because the stock is valued as bought; the yield matters when the stock becomes dishes.

Keep the two clear: stock is counted and valued as bought, and yield turns the purchase price into the cost of each portion.

Yield and portion control work together. Yield tells the kitchen how much usable product it gets from what it buys; portion control makes sure each plate uses the amount the costing expects. A good yield wasted by generous portions is a good yield lost.

Weigh portions during prep and check them during service. A portion that drifts above its weight by a tenth costs as much as a tenth less yield.

Some products arrive ready to use: fillets, peeled vegetables, prepared sauces. Their yield is close to complete, but their price is higher. Comparing them with the raw product, after yield and labour, shows whether preparing in-house is worth it.

Include the cook's time in the comparison. A whole fish that yields a cheaper fillet after twenty minutes of a cook's work may not be cheaper at all.

Yield can shape the menu. A dish that uses the whole of an ingredient, the fillet for a main and the trimmings for a starter or a soup, raises the effective yield of the ingredient and lowers the cost of both dishes.

Design dishes that use the trimmings. A menu built with yield in mind wastes less and earns more from the same purchases.

Every new dish that uses a prepared ingredient needs a yield before it is costed. Test the yield during the dish's development, so the price is set from the real cost.

A new dish costed from the invoice price, and priced accordingly, may look profitable on paper and lose money in the kitchen.

Liquids have yields too. A stock reduces as it simmers; a sauce reduces to concentrate it; a soup loses volume. A recipe that starts with ten litres and ends with six has a yield of 60 per cent, and the cost of each portion is the cost of the batch divided by the portions the six litres make.

Measure the final volume of each batch, at least occasionally, to check the recipe yield.

Explain yield to the team in terms they can see: "we pay for the whole fish, but we only sell six tenths of it". Show the trimmings from a yield test beside the usable product.

A team that understands yield trims more carefully, uses trimmings where it can and portions accurately, because they can see what each mistake costs.

In a group with a central kitchen, yields should be measured where the preparation happens, and the usable cost passed to the venues. A venue that receives prepared portions from the central kitchen should pay for the usable product, not the raw.

Keep the yields consistent across the group, so every venue's costings are built on the same figures.

Yield should guide buying as well as costing. A supplier whose product yields more, at a similar price, is the better supplier; a cheaper product with a much lower yield is a false saving.

Share yield results with suppliers. A supplier who knows the kitchen measures the yield of their fish has a reason to send fish that yields well.

Poor storage lowers yield. Vegetables that wilt, fish that is stored badly and meat that dries out in the fridge all lose usable weight before they reach the board.

Store each ingredient as it needs, and use the oldest first. A good yield on arrival can be lost in a few days of careless storage.

Record the yield in each recipe that uses the ingredient, so the cost per portion is always calculated from the usable cost. A recipe that lists 180 grams of salmon fillet, with the salmon's yield and usable cost beside it, shows its true cost at a glance.

When the yield changes, every recipe that uses the ingredient changes with it. Keeping the yield in one place, used by every recipe, makes the update simple.

Sometimes the yield test and the portions sold do not add up: the kitchen should have got forty portions from a delivery and sold only thirty-four. The gap may be over-portioning, waste, mistakes or a lower yield than the test showed.

Investigate the gap like any variance: check the portions, the waste and the test itself before drawing conclusions.

Run yield tests on a quiet afternoon, not during prep for a busy service. A cook who is rushed trims differently, and the test should measure the kitchen's normal practice under normal conditions, with time to weigh everything carefully and write it down.

An invented seafood restaurant costs its dishes from invoice prices. Its actual food cost is several points above its theoretical cost every month, and the owner suspects waste. The head chef runs yield tests on the five most-used ingredients: whole salmon, whole sea bass, prawns, lemons and potatoes, three times each.

The salmon yields 60 per cent, the sea bass 45 per cent, the prawns 55 per cent after peeling. Recosted with the usable prices, three dishes turn out to be priced too low; two are repriced and one is changed to use fillets bought ready prepared. The bones go into a new fish soup. The next month, the actual and theoretical food costs are within a point of each other.

servearound does not hold recipes, ingredients, yields or costs, so yield tests and costings are kept in your own records; inventory tracking is coming. What it holds is the sales side that costing is checked against.

The menu report shows the units sold of every dish over any dates, which, with your own recipes and yields, gives the quantity of each ingredient the kitchen should have used, to compare with what it bought. See Analytics.

The usable part of an ingredient as a share of what was bought.

Because the kitchen pays for everything it buys but uses only part of it, so costings must use the usable cost.

Weighing an ingredient as bought, preparing it normally, weighing the usable part and dividing.

The share of a whole piece of meat or fish that becomes usable portions.

The number of portions a recipe produces.

A few times a year for key ingredients, and whenever a supplier or season changes.

The most expensive, most used and most heavily prepared.

Use what can be used, such as bones for stock, and record the rest as prep waste.

What is yield? It is the usable part of an ingredient as a share of what was bought. Trim yield, butchery yield, cooking yield and recipe yield all change the real cost of a dish, and costings that ignore them understate the cost of every plate.

Run a yield test in twenty minutes, repeat it three times and use the average. Cost every dish from the usable price, compare suppliers on usable cost, use the trimmings where you can and reduce prep waste through training, recording the yields so they outlast any one chef.