Pack price
What the kitchen paid for the supplier pack, in the unit it was bought.
Kitchen costing guide
Food cost per portion, without the guesswork.
The price on the supplier invoice is not the cost of the portion on the plate. The useful calculation connects pack price, usable yield, recipe quantity and portions.
The working calculation
Start with the cost of the usable amount, then divide the recipe batch by its yield.
portion cost = Σ (pack price × recipe quantity ÷ usable pack quantity) ÷ portionsThree numbers need to stay visible
Usable yield
What remains after trim, cooking, reduction or other real preparation loss.
Recipe quantity
The amount that actually goes into the batch, not the amount that arrived on the invoice.
A practical before-service check
Update one ingredient
Change the pack price or yield using a real supplier update, not a made-up average.
Find the linked recipes
A prep or ingredient can sit inside several dishes. The affected family matters more than one isolated calculation.
Review the decision
Check the new portion cost, menu price, portion size and any prep sheets that now need printing.
Worked example: braised beef shin
The gap between the invoice price and the plate cost is not small. On this dish it is more than double.
Butchery yield
5 kg of bone-in shin at £8.90 per kilo is £44.50. Boned and trimmed, it gives 3.1 kg of usable meat — a 62% yield. That makes the usable raw cost £44.50 ÷ 3.1 = £14.35 per kilo, not £8.90.
Cooking loss
A long braise takes roughly 30% of the weight out again. 3.1 kg raw comes out at 2.17 kg cooked, so the cost of what you can actually plate is £44.50 ÷ 2.17 = £20.51 per cooked kilo.
Portion cost
At a 140 g cooked portion: 0.14 × £20.51 = £2.87.
Cost it the quick way — 140 g at the invoice price of £8.90 per kilo — and you get £1.25. The real figure is 130% higher. A menu priced on the quick number is not slightly out; it is out by more than the whole margin.
Cost the sub-recipe once, use it everywhere
Most of what a kitchen serves is not a single ingredient. It is a prep that goes into a dish, and a prep inside that prep. Cost each one as a batch, divide by its yield, and treat the result as an ingredient with a price per portion.
The braising liquor for that shin: a 750 ml bottle of red wine at £5.20, mirepoix £1.30, tomato purée £0.35, thyme and bay £0.40, and beef stock made from the bones you already paid for in the 5 kg pack, costed at £2.59. That is £9.84 for a batch yielding 24 portions, so £0.41 a plate.
Do that once and the number is reusable. When the wine goes up, one batch cost changes and every dish that draws on it changes with it — provided the link is recorded somewhere other than the head chef's memory.
Beef 140 g
£2.87
Mash, greens
£0.68 + £0.55
Braising sauce
£0.41
Full plate cost: £2.87 + £0.68 + £0.55 + £0.41 = £4.51.
Turning portion cost into a menu price
Only one of these two numbers has VAT in it, and it is not the one on the invoice.
Food bought into a kitchen is mostly zero-rated, so your £4.51 is already a net figure. Food eaten on the premises is standard-rated at 20%, so the menu price is not. The two have to be brought onto the same footing before you divide.
Put the shin on the menu at £16.50. That is £16.50 ÷ 1.2 = £13.75 excluding VAT. The food cost is £4.51 ÷ £13.75 = 32.8%, a gross profit of 67.2% — inside the 30–35% band most UK kitchens work to.
Divide the same £4.51 by the £16.50 the guest actually paid and you get 27.3%, which would put the dish in a band it has never been in. The dish did not improve; you measured it against money that belongs to HMRC.
Where portion costs quietly drift
Over-portioning
Serving 150 g against a 140 g spec is 7.1% more beef, or just over 20p a plate on this dish. Forty covers a week is £8.20 a week and £426 a year, from one dish and one scoop.
Yields recorded once and never retested
Yield moves with the season, the supplier and the person holding the knife. Reweigh the trim on a delivery twice a year rather than trusting a figure someone wrote down in 2023.
Pack size changes without a price change
The invoice total looks the same because the pack got smaller. Cost per usable kilo went up and nothing on your sheet noticed.
Prep waste treated as free
Peelings and trim are already paid for; that is what the yield percentage captures. But a batch of sauce that splits and gets binned is a second cost, and it belongs in wastage, not in the portion cost.
Freebies, staff food and comps
They do not change the portion cost, but they change the food cost percentage, because the food left the kitchen and no sale came back. Track them separately so the dish is not blamed for them.
Common questions
Is food cost percentage the same as portion cost?
No. Portion cost is the money spent on the ingredients for one portion. Food cost percentage compares that cost with the selling price: portion cost ÷ ex-VAT menu price × 100.
Should I use pack price or usable yield?
Use the pack price together with the usable quantity. If a 5kg pack produces only 4.2kg of usable product, the recipe cost should reflect the 4.2kg, not the label weight alone.
Do I include VAT in the portion cost?
No. Most kitchen food is zero-rated so the invoice is already net. Bring the selling price down to ex-VAT — divide by 1.2 for standard-rated eat-in food — before you compare the two.
How do I cost an ingredient that shrinks when cooked?
Apply the loss to the batch, not to the portion. Divide the batch cost by the cooked weight it actually produced, then multiply by your plated portion size.
Why can a correct spreadsheet still be wrong?
The formula can be correct while the inputs are stale. An old pack size, yield assumption or shared-prep link can quietly move every affected dish.
Keep reading
- Restaurant menu pricing — turning a portion cost into a price the menu can carry.
- Yield percentage and trim waste — how to measure the 62% rather than guess it.
- Costing a sub-recipe — batch sauces, stocks and butters rolled into a dish cost.
- Prime cost for a UK restaurant — where portion costs sit once labour joins them.
- Food stock take and actual food cost — the count that proves your portion costs are real.
Run one real recipe, then cost the whole menu.
PrepSheet's free tools let you test a dish. If the real job is finding low-margin dishes across the menu, the Food Cost & Menu Pricing template keeps the recipes, target GP and pricing decisions in one working pack.