Why most costings are wrong
Kitchens cost ingredients at invoice price per kilo and ignore the losses from peeling, trimming, bones and cooking. Then they cost the dish once at launch and never again — so food looks cheaper to produce than it is. This covers costing one portion accurately; the food cost % guide turns that into GP and a menu price.
02Costing, step by step
- List every ingredient — including oil, finishing butter, salt, garnish, sauces.
- Take pack cost and pack size from the latest invoice.
- Unit cost = pack cost ÷ pack size. £72.50 for a 5kg case = £14.50/kg.
- Apply yield: quantity to buy = quantity needed ÷ yield %. At 50% yield, buy 2kg for every 1kg served.
- Line cost = quantity to buy × unit cost.
- Add the lines for the batch, divide by portions.
Worked example: short rib, 10 portions
| Ingredient | Pack | Unit cost | Needed | Yield | To buy | Line |
|---|---|---|---|---|---|---|
| Beef short rib, bone-in | £72.50 / 5kg | £14.50/kg | 1.8kg | 50% | 3.6kg | £52.20 |
| Maris Piper potatoes | £12.00 / 25kg | £0.48/kg | 1.5kg | 80% | 1.88kg | £0.90 |
| Butter | £6.80 / 1kg | £6.80/kg | 0.25kg | 100% | 0.25kg | £1.70 |
| Double cream | £4.20 / 1L | £4.20/L | 0.2L | 100% | 0.2L | £0.84 |
| Carrots | £9.00 / 10kg | £0.90/kg | 1kg | 85% | 1.18kg | £1.06 |
| Red wine (cooking) | £6.00 / 75cl | £8.00/L | 0.5L | 100% | 0.5L | £4.00 |
| Stock, mirepoix, herbs | from stock sub-recipe | £3.50 | ||||
| Oil, seasoning, garnish | allowance | £1.50 | ||||
| Batch (10 portions) | £65.70 | |||||
| Per portion | £6.57 | |||||
At £26 on the menu, the ex-VAT price is £21.67 — a food cost of 30.3%. The short rib is 79% of batch cost: that's the line to watch when prices move. Example prices only.
Yield, waste and sub-recipes
Yield is the share of what you buy that reaches the plate. Ignore it and trimmed, peeled or boned ingredients are under-costed — sometimes by half. Run a yield test: weigh on arrival, prep as normal, weigh the usable portion, divide. 5kg of carrots yielding 4.25kg after prep is 85%. Test across deliveries and chefs, average it, retest on a new supplier or spec.
Cost stocks, sauces, dressings, doughs and pickles as standalone sub-recipes with a cost per litre or kilo. Update one sub-recipe and every dish that uses it updates with it.
05The 14-allergen matrix
The 14 UK-regulated allergens: celery · cereals containing gluten · crustaceans · eggs · fish · lupin · milk · molluscs · mustard · tree nuts · peanuts · sesame · soya · sulphites. A matrix lists all 14 against every dish so staff can answer fast. Extract (C = contains, ? = check supplier spec):
| Allergen | Short rib | Fish & chips | Mushroom risotto | Sticky toffee |
|---|---|---|---|---|
| Celery | C | C | ||
| Gluten cereals | C | C | ||
| Eggs | C | ? | C | |
| Fish | C | |||
| Milk | C | C | C | |
| Mustard | C | |||
| Sulphites | C | ? | C | ? |
The "?" entries are deliberate — batter beer, pudding dates and some hard cheeses may contain sulphites or egg, and only the supplier's product spec confirms it. Build the matrix from recipe specs and supplier specs, never memory; update it the day anything changes; date every version; account for cross-contact (shared fryers, boards, garnishes); and train front of house to use it.
06How Chef's Intelligence helps
"Flag every allergen across this menu and build me the matrix. Mark anything you can't confirm from the recipe."
Output: a filled-in costing sheet with the margin-damaging lines highlighted, and a matrix with unconfirmed items flagged for spec checks. The matrix is a food safety document — a person checks and signs it off.
07Questions
How do I calculate recipe cost?
Per ingredient: unit cost × (quantity needed ÷ yield). Sum the batch, divide by portions.
What is yield percentage?
The usable share after prep or cooking — found by weighing, not guessing.
Must restaurants have an allergen matrix?
The law requires accurate allergen information; it doesn't mandate a format. A matrix is the most practical way to deliver it.
Zone 02
Menu & Product Dev · 7 skills · £29/mo
Dish development, recipe bibles, costing, allergens and tasting menus. Full Suite £89/month.