To cost a recipe in a UK kitchen, add up the cost of every ingredient at the exact quantity used, divide by the number of portions it yields, and you have your cost per portion. To check whether that price works, divide the cost per portion by the menu selling price (excluding VAT) and multiply by 100 — that's your food cost percentage, which most UK kitchens aim to keep between 25% and 35%.
That's the short answer. Below is the full method, with the real-world details that trip people up: pack sizes, waste, yield loss, and VAT.
Write out every single ingredient — including the ones people forget, like oil for frying, seasoning, garnish, and the splash of cream in a sauce. Then convert each to the unit you'll actually buy it in.
For example, a portion of mushroom soup might use:
Be honest about quantities. Guessing "a knob of butter" is where margins quietly disappear. Weigh things once and write the grams down.
This is the part most people get wrong. You don't cost an ingredient by the pack — you cost it by the gram, millilitre, or each.
Take what you paid and divide by the pack quantity:
Always use the price you actually pay your supplier, not the supermarket shelf price. And use the ex-VAT price. Most raw food ingredients in the UK are zero-rated for VAT, but some aren't — confectionery, snacks, alcohol, and hot takeaway items can carry VAT, so check your invoices rather than assuming.
Now multiply each ingredient's quantity by its cost per unit:
| Ingredient | Quantity | Unit cost | Line cost |
|---|---|---|---|
| Chestnut mushrooms | 200g | £0.0032 | £0.64 |
| Onion | 50g | £0.0011 | £0.06 |
| Butter | 15g | £0.006 | £0.09 |
| Double cream | 100ml | £0.0018 | £0.18 |
| Stock | 250ml | £0.0008 | £0.20 |
| Seasoning | 5g | — | £0.03 |
| Total | | | £1.20 |
If this recipe makes 4 portions, your cost per portion is £1.20 ÷ 4 = £0.30.
Raw ingredient cost isn't the whole story. Two things eat into it:
Trim and prep waste. If you buy whole carrots and peel them, you're paying for the peel you throw away. A carrot might lose 15–20% of its weight in prep. So if a recipe needs 800g of peeled carrot, you actually need to buy and pay for around 1kg.
To handle this, add a yield factor. If usable yield is 80%, divide your required weight by 0.8 to get the purchase weight, then cost that.
Cooking loss. Meat especially shrinks. A 200g raw chicken breast might serve as 150g cooked. If your portion is defined by cooked weight, cost the raw weight you actually started with.
Ignoring these two factors is the single biggest reason kitchens think they're making money when they're not.
Cost per portion only means something next to your selling price. The standard UK calculation is:
Food cost % = (cost per portion ÷ selling price ex-VAT) × 100
If your soup costs £0.30 a portion and you sell it for £5.50:
That's an excellent margin for a soup. Most operators target an overall food cost of 28–32%, balancing cheap dishes (soups, pasta) against expensive ones (steak, fish) so the average lands where it needs to.
Always strip out VAT before calculating. That £5.50 on the menu isn't all yours — £0.92 belongs to HMRC. Costing against the gross price flatters your margins and leads to underpricing.
Once you know your cost per portion, you can set a price to hit a target food cost:
Selling price (ex-VAT) = cost per portion ÷ target food cost %
For a £2.50 dish at a 30% target:
Round to a sensible menu number and you're done.
Costing is per-portion, but kitchens cook in batches. If your costed recipe is for 4 portions and you need 40 for a function, multiply every ingredient by 10. Keep the per-portion cost the same, but the scaled quantities tell your team exactly what to prep and order.
This is also where a prep sheet earns its keep: a printed list of scaled quantities your team can follow during service, with the costings baked in.
1. List every ingredient and exact quantity.
2. Convert pack prices to cost per gram/ml/each, ex-VAT.
3. Multiply quantity × unit cost and total it.
4. Adjust for trim and cooking yield.
5. Divide by portions for cost per portion.
6. Calculate food cost % against the ex-VAT selling price.
7. Re-cost regularly.
Doing this by hand or in a spreadsheet works, but it's slow — and the maths gets fiddly once you're juggling pack sizes, yields, VAT and batch scaling across a whole menu.
If you'd rather paste in a recipe and get the cost per portion, food cost % and a printable prep sheet straight away, PrepSheet does exactly that — it's free, runs in your browser with no signup, and your recipes save locally. You can try it here whenever you're ready.