Roast leg of lamb: how much it costs to make, per portion
Roast leg of lamb costs £3.12 a portion in ingredients (£24.92 for a batch of 8), from UK pack prices dated 25 October 2026. To reach 68% GP, the UK food benchmark, it needs to sell for at least £11.68 including 20% VAT (£9.74 without).
Roast lamb for a Sunday menu: boneless leg studded with garlic and thyme, roasted pink and carved eight ways, with mint sauce and gravy. Costed from JJ Foodservice and Morrisons prices read on 25 October 2026.
The lowest price is the one that just reaches 68% GP, the UK food GP benchmark (UKHospitality × Christie & Co, 2022: 65.9–69% food GP across every segment). It covers the ingredients at a normal margin, not staff, rent or energy, and most cafés, pubs and takeaways charge more for simple dishes. Check what places near you charge. GP is worked out on the ex-VAT price.
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Ingredients and cost, 8 portions
| Ingredient | Pack price | Pack size | Used | Cost |
|---|---|---|---|---|
| Boneless lamb leg | £14.69 | 1000 g | 1600 g | £23.50 |
| Garlic | £3.49 | 1000 g | 20 g | £0.07 |
| Fresh thyme | £1.79 | 100 g | 10 g | £0.18 |
| Rapeseed oil | £9.49 | 5000 ml | 20 ml | £0.04 |
| Table salt | £8.99 | 12500 g | 10 g | £0.01 |
| Ground black pepper | £22.99 | 1750 g | 2 g | £0.03 |
| Mint sauce | £0.70 | 180 g | 180 g | £0.70 |
| Gravy granules | £24.99 | 5000 g | 80 g | £0.40 |
| Batch total | £24.92 | |||
| Per portion (÷ 8) | £3.12 | |||
Cost per line is pack price × (amount used ÷ pack size), the same sum the tool runs. Change one pack price and every line that uses it moves.
What it really costs: waste and staff time
| Ingredients | £3.12 |
| Waste allowance, 5% (trim, ends, the odd one binned) | £0.16 |
| Staff time: 15 min hands-on for the batch of 8 at £12.71/hr + 25% on-cost | £0.50 |
| Food, waste and staff per portion | £3.78 |
At the lowest price (£9.74 ex VAT) that is 39% of the price, before rent, energy and everything else. Many UK sites aim to keep food plus staff (prime cost) at or under 60–65% of sales. The staff line counts hands-on prep only, not unattended cooking, and uses the April 2026 National Living Wage; put your own rate, minutes and waste in the calculator's real cost section or the prime cost calculator. Every dish side by side: the UK dish cost index.
Method
- Stab the lamb all over and push in slivers of garlic and thyme; rub with oil, salt and pepper.
- Roast at 200 °C for 20 minutes, then at 170 °C until the centre reaches 60 °C for pink, about 50 minutes more.
- Rest for 20 minutes, carve into eight portions and serve with mint sauce and gravy.
Costing notes
Cooked weight. USDA figures give about 86% lean meat from a roasted boneless leg once the cooked joint is trimmed of fat (lamb leg yield). Roasting loss comes before that, so weigh your cooked joint once and set the portion count from it.
Where the prices came from
JJ Foodservice collection prices (single-unit price, no multi-buy tiers) and Morrisons shelf prices, read on 25 October 2026. Morrisons lines are used where JJ Foodservice listed no equivalent that day; wholesale is usually lower, so treat those lines as cautious. Prices are as listed; JJ does not label VAT on most lines, and most raw food is zero-rated in the UK while alcohol and some ingredients carry standard-rate VAT. Your supplier's price is the one that matters: open the recipe and type it in.
- Boneless lamb leg: Boneless lamb legs, box approx 8-11 kg, priced per kg (MEA404), per kg, £14.69 collection — JJ Foodservice, accessed 2026-10-25
- Garlic: Fresh garlic (VEG784), 1 kg, £3.49 collection — JJ Foodservice, accessed 2026-10-25
- Fresh thyme: Fresh thyme (VEG962), 100 g, £1.79 collection — JJ Foodservice, accessed 2026-10-25
- Rapeseed oil: KTC rapeseed oil (OIL110), 5 litres, £9.49 collection — JJ Foodservice, accessed 2026-10-25
- Table salt: JJ table salt (SPI019), 12.5 kg, £8.99 collection — JJ Foodservice, accessed 2026-10-25
- Ground black pepper: JJ ground black pepper (SPI596), 1.75 kg, £22.99 collection — JJ Foodservice, accessed 2026-10-25
- Mint sauce: Morrisons Mint Sauce (retail), 180 g, £0.70 shelf price — Morrisons (retail), accessed 2026-10-25
- Gravy granules: Dinaclass original gravy mix, 2 x 2.5 kg (SAU538), 5 kg, £24.99 collection — JJ Foodservice, accessed 2026-10-25
More costed dishes: pub and restaurant classics
- Shepherd's pie — £1.58 a portion
- Fishcakes — £2.05 a portion
- Garlic bread — £0.32 a portion
- Halloumi fries — £2.27 a serve