Pack price
What the kitchen paid for the supplier pack, in the unit it was bought.
Kitchen costing guide
How to calculate food cost per portion
Divide the pack cost by the usable quantity to get a unit cost, multiply by the amount the recipe actually uses, total every line, then divide the batch cost by the portions it really yielded. The price on the supplier invoice is not the cost of the portion on the plate.
The formula, and one worked line
Portion cost = Σ (pack cost ÷ usable pack quantity × recipe quantity) ÷ portions yielded
5 kg of bone-in beef shin at £8.90/kg costs £44.50. Boned and trimmed it gives 3.1 kg, and a long braise takes it to about 1.92 kg cooked — so the plateable cost is £44.50 ÷ 1.92 = £23.1771 per kilo. A 140 g portion is 0.14 × £23.1771 = £3.24. Costed the quick way, at the £8.90 invoice price, the same portion reads £1.25.
Keep the unrounded figures in the working and round only what you display. The full example is worked out below.
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 35–40% of the weight out again on a collagen-heavy cut like shin. Weigh it: 3.1 kg raw comes out at about 1.92 kg cooked (a 62% cooking yield), so the cost of what you can actually plate is £44.50 ÷ 1.92 = £23.18 per cooked kilo. That is in line with USDA measurements, where one pound of bone-in shank crosscut yields about 170 g of cooked lean — roughly 37–38% of what came off the invoice.
Portion cost
At a 140 g cooked portion: 0.14 × £23.1771 = £3.2448, displayed as £3.24.
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 about 160% higher. A menu priced on the quick number is not slightly out; it is out by more than the whole margin.
Two yields, not one
Trim yield and cooking yield are separate measurements and they multiply: 62% × 62% = a combined yield of 38.4%, which is the 1.92 kg you can actually plate out of the original 5 kg. Measure each stage rather than carrying one blended figure — the AP-to-EP yield calculator does the arithmetic and shows the true usable cost per kilo.
Round money last
Every intermediate value above is unrounded: £44.50 ÷ 3.1 = £14.3548/kg, £44.50 ÷ 1.92 = £23.1771/kg, portion £3.2448. Rounding each step to the penny before the next one drags the answer, and on a batch of thirty portions the drift is real money. Round only the figure that goes on the sheet.
Invoice-to-plate audit trail
Every input in that chain came from somewhere and goes stale on its own schedule. Record where each one came from, so a wrong answer can be traced to a wrong input rather than re-derived from scratch.
| Input | Source | Unit | Recheck when | Reused by |
|---|---|---|---|---|
| Pack cost £8.90/kg | Supplier invoice, with SKU | £ per kg | Every price change or pack-spec change | Every shin dish and prep |
| Trim yield 62% | Weighed on delivery: 3.1 kg from 5 kg | % | Twice a year, and on any supplier or spec change | Raw usable cost per kg |
| Cooking yield 62% | Weighed after the braise: 1.92 kg from 3.1 kg | % | Any change to method, time or batch size | Cooked cost per kg |
| Portion 140 g | Recipe spec | g | Whenever the plate changes; spot-check on the line | Portion cost, theoretical food cost |
| Braising liquor £0.41 | Sub-recipe batch cost ÷ 24 portions | £ per portion | Any component price change | Every dish using that liquor |
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. The rule is one line: batch cost ÷ finished measured yield = the sub-recipe's unit cost. Cost it once, then use that unit cost as an ingredient in every dish that draws on it.
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
£3.24
Mash, greens
£0.68 + £0.55
Braising sauce
£0.41
Full plate cost: £3.24 + £0.68 + £0.55 + £0.41 = £4.88. That is a sum of displayed values; carrying the unrounded beef figure (£3.2448) gives £4.8848, which rounds to the same £4.88.
Turning portion cost into a menu price
Cost and selling price have to be on the same VAT footing before you divide one by the other.
On the cost side, use the price the business actually bears. If you are VAT-registered, you recover input VAT, so cost on ex-VAT prices. If you are not registered, or the VAT is otherwise irrecoverable, the real cost is the price you paid including VAT. Most food bought into a kitchen is zero-rated so the invoice is already net — but confectionery, savoury snacks, ice cream, most soft drinks and all alcoholic drinks are standard-rated (HMRC Notice 701/14), and so are non-food consumables. Check the invoice rather than assuming.
On the sales side, use net sales. Restaurant and café meals, other on-premises consumption and qualifying hot takeaway food are standard-rated; cold takeaway food is generally zero-rated (HMRC Notice 709/1). The UK standard rate is currently 20% (GOV.UK), so divide a standard-rated menu price by 1.2 — but use the treatment that actually applies to the supply rather than hard-coding 20% across the menu.
Put the shin on the menu at £16.50 eat-in. That is £16.50 ÷ 1.2 = £13.75 excluding VAT. The food cost is £4.88 ÷ £13.75 = 35.5%, a gross profit of 64.5%. For where that sits against dated UK survey evidence, see the UK food cost and GP benchmarks.
Divide the same £4.88 by the £16.50 the guest actually paid and you get 29.6%, 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
Everything on this page is a theoretical cost: what the dish should cost if the spec is followed. A stock take gives the actual cost for a period, and the gap between the two is the thing worth investigating. That gap is not all waste — over-portioning, comps, staff food, a stale yield figure and a miscounted stock line all live in it, and they need different fixes.
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?
Use the cost the business actually bears. A VAT-registered kitchen recovers input VAT, so it costs on ex-VAT prices; a business that cannot recover the VAT should use the price it paid. Most kitchen food is zero-rated anyway, but standard-rated lines exist — alcohol, soft drinks, crisps, confectionery, ice cream. Then bring the selling price down to ex-VAT before you compare the two: divide by 1.2 for a standard-rated eat-in sale.
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.
- AP-to-EP yield calculator — calculate measured trim, cooking loss and usable cost per kg.
- 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.