How long to roast a lamb joint
Roast a lamb joint for
25min per 450g
Plus 25 minutes (about 56 minutes per kg, plus 25). Oven at 190°C (375°F, gas mark 5).
Times by weight
| Weight | Cooking time |
|---|---|
| 1kg (2.2lb) | 1 hour 25 min |
| 1.5kg (3.3lb) | 1 hour 50 min |
| 2kg (4.4lb) | 2 hours 20 min |
| 2.5kg (5.5lb) | 2 hours 45 min |
| 3kg (6.6lb) | 3 hours 15 min |
Work out an exact weight, and when to put it in.
Oven and resting
Oven: 190°C (375°F, gas mark 5). For a fan oven, set it 10 to 20°C lower. Cooking times stay the same.
Rest for 20 minutes before carving (Q Guild).
How to tell it's done
Cook until it reaches 70 to 75°C for medium, 75 to 80°C for well done (Q Guild).
A whole leg or shoulder can be served pink as long as the whole outside surface is properly cooked. Rolled or stuffed joints must be cooked all the way through. (Food Standards Agency)
Meat keeps cooking while it rests. Take it out about 5 to 10°C below the target and let the rest finish it. (Q Guild)
US guidance: USDA's safe minimum is 145°F (63°C), with a rest of at least 3 minutes (FoodSafety.gov (USDA)). USDA's figure is a safety minimum, not a doneness guide.
Times from Q Guild, checked 2026-10-24.