Cooked vs raw weight: how much shrinkage to allow on roast joints
Raw weight to buy = the cooked weight you want to serve ÷ (1 − roasting loss): at a 30% loss, a 150 g cooked portion of beef needs 214 g raw, and every kilo of raw joint gives 700 g on the board. The 30% is the assumption in ChefSums' costed roast beef dinner (220 g raw topside a portion, about 154 g cooked), not a measured figure for your oven, so weigh your own joint before and after and use that.
Raw weight needed for a cooked portion
| Cooked portion | 20% loss | 25% loss | 30% loss | 35% loss | 40% loss |
|---|---|---|---|---|---|
| 100 g | 125 g | 133 g | 143 g | 154 g | 167 g |
| 120 g | 150 g | 160 g | 171 g | 185 g | 200 g |
| 150 g | 188 g | 200 g | 214 g | 231 g | 250 g |
| 180 g | 225 g | 240 g | 257 g | 277 g | 300 g |
| 200 g | 250 g | 267 g | 286 g | 308 g | 333 g |
Method: raw = cooked ÷ (1 − loss). The loss percentages are a range to read across, not published figures for particular cuts. Loss depends on the cut, its fat cover, the oven temperature and, most of all, how far you cook it.
What the cooked weight does to the cost
Cost a roast on what you serve, not what you bought. At £10.99 a kilo raw (the topside price on our roast beef dish), the cost per cooked kilo is:
| Roasting loss | Cooked kg from 1 kg raw | Cost per cooked kg | Cost of a 150 g cooked portion |
|---|---|---|---|
| 20% | 0.80 | £13.74 | £2.06 |
| 25% | 0.75 | £14.65 | £2.20 |
| 30% | 0.70 | £15.70 | £2.36 |
| 35% | 0.65 | £16.91 | £2.54 |
Method: cost per cooked kg = raw price per kg ÷ (1 − loss). Price from the roast beef dinner page, where its date and supplier are listed.
Whole chicken: the bone comes first
A whole bird loses weight to bone before it loses any in the oven. In USDA Agriculture Handbook No. 102, Food Yields (1975), an oven-ready chicken gave 58% raw meat with skin (range 50–62%) and 47% without skin (item 582, US samples). Roasting loss then comes off that. Full figures: whole chicken yield.
Measure your own in four steps
- Weigh the joint raw, trimmed and tied, as it goes in.
- Roast to your normal spec and rest it as you would for service.
- Weigh it again before carving. Loss = 1 − cooked ÷ raw.
- Do it three times and use the average. Put the figure on the spec sheet and in the yield calculator.
Questions chefs ask
How much does beef shrink when roasted?
It depends on the cut and how far you cook it. ChefSums' roast beef costing assumes 30%; weigh your own joint before and after to get your figure.
How much raw beef do I need for 10 people?
At 150 g cooked each and a 30% loss: 10 × 150 ÷ 0.7 = 2.14 kg raw. Our costed roast uses 2.2 kg for ten.
Should I cost on raw or cooked weight?
On the cooked weight you serve. The raw price per kilo understates the plate cost by the whole of the roasting loss.
Sources
More chef questions: Food cost % by venue type · Menu price multiplier table · Pub food and drink GP mix · Portions per kg · Kitchen energy cost per dish · Kitchen staff cost 2026/27 · Sunday roast cost per cover · Prep par and shelf life · UK wholesale staple prices
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