Recipe yield calculator: calculate the true cost per portion

The weight on the delivery note is not always the weight you can sell. Meat loses trim, fish loses bones and skin, vegetables lose peel and tops, and almost everything changes weight during cooking. Cost a portion from the purchased weight and the number can look precise while being wrong from the start.

The recipe yield formula

First find the usable net yield: the weight or number of portions left after preparation and cooking. Then calculate cost per usable unit: total batch ingredient cost ÷ net yield. Finally, multiply that unit cost by the amount served. Use grams for weight, millilitres for liquid and each for count, rather than mixing units.

Cost per portion = total batch cost ÷ usable net yield × portion size.

Worked example: cooked chicken

You buy 5 kg of chicken for £30. After trimming and cooking, it weighs 4.5 kg. The cost per usable gram is £30 ÷ 4,500 g = 0.667p. A 180 g portion therefore costs £1.20 in chicken. If you had divided by the 5 kg purchased, you would have called that portion £1.08 and under-costed every plate by 12p.

Do not confuse yield with portions

Yield is what the batch produces; portions are how you choose to serve it. The same 4.5 kg batch can make 25 portions at 180 g, 30 portions at 150 g, or something uneven if the kitchen plates by eye. Record both the net yield and the number of portions your team actually serves, then review them when the prep method changes.

What belongs in the portion cost

• Ingredients: use the current supplier price excluding VAT, including oil, seasoning and garnish when they are part of the standard recipe.
• Labour and packaging: add them separately if you use them in menu costing; they are not part of the food yield calculation.
• Selling price: when checking food cost percentage or gross profit, compare the portion cost with the menu price excluding VAT.
• Waste: normal trim and cooking loss belong in yield. Burnt batches, dropped plates and spoilage are waste to record separately.

How to get a yield you can trust

1. Weigh or count the raw ingredients before prep.
2. Prepare and cook them as the kitchen normally does.
3. Weigh or count the usable result, not the tray or container.
4. Repeat the check on another delivery if size or quality varies, then use a sensible average rather than one unusually good batch.
5. Update the recipe whenever the spec, supplier pack or serving size changes.

Using yields in FoxEra

For a batch or sub-recipe, FoxEra lets you record portions produced and the net yield in grams, millilitres or each. Its recipe costing uses the ingredient quantities you enter, so the important part is still the measurement: enter the usable yield and the portion size your kitchen actually serves. Software can recalculate a price change; it cannot discover an unmeasured cooking loss.

The check worth doing this week

Pick the ingredient with the highest weekly spend or the dish with the thinnest margin. Measure one normal batch from raw to usable yield, cost the standard portion, and compare it with the recipe you currently hold. Do not change a menu price from one observation alone, but do not keep an old yield just because it has always been there either.