Leg of lamb yield: how much is usable after prep (AP to EP %)
Leg of lamb: about 72% usable going roasted bone-in leg to boned lean and fat, with a published range of 71–72%. That is a cost factor of 1.39: for every kilo you need ready to use, buy 1.39 kg as purchased.
Yield by preparation stage
| Stage | Average | Range | What is lost | USDA item |
|---|---|---|---|---|
| Roasted bone-in leg → boned lean and fat | 72% | 71–72% | Bone | 1396 |
| Roasted bone-in leg → boned lean only | 58% | 56–69% | Bone and fat | 1397 |
| Roasted boneless leg → lean only | 86% | 75–88% | Fat | 1398 |
| Roasted bone-in shoulder → boned lean and fat | 75% | 73–77% | Bone | 1402 |
These figures start from the roasted joint, so add your own roasting loss on top. Trimming the fat as well as the bone takes a bone-in leg from 72% down to 58% of its cooked weight.
What the yield does to the cost
| Usable leg of lamb needed | Buy (as purchased) at 72% |
|---|---|
| 1 kg | 1.39 kg |
| 5 kg | 6.94 kg |
| 10 kg | 13.89 kg |
Use 72% in the yield calculator →
Yield source: USDA Agriculture Handbook No. 102, Food Yields Summarized by Different Stages of Preparation (Matthews and Garrison, USDA Agricultural Research Service, 1975), Table 1, items 1396, 1397, 1398, 1402 (US samples of lamb legs and shoulders, roasted). Your own case is the real number: weigh it in the yield calculator.
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