Leg of Lamb Cooking Time by Weight

per 500g: 20 min pink, 25 min medium, 30 min well done (at 180°C fan) at 180°C (fan 160°C / 356°F, gas mark 4).

A roast leg of lamb is a real occasion dish, and like roast beef, the timing depends on how pink you like it. Sear it first, then roast at 180°C (fan) using the per-500g guide, and always rest it well.

Times by doneness

Per 500g at 180°C fan, after the initial sear: about 20 minutes for pink, 25 for medium, and 30 for well done. A meat thermometer beats the clock — pull the joint at roughly 55°C for pink, 65°C for medium, 72°C for well done, remembering it climbs a few degrees as it rests. A whole leg can safely be served pink; rolled joints should be cooked through.

Method

1. Bring the lamb to room temperature and heat the oven to 220°C.
2. Roast at 220°C for 20 minutes to brown, then reduce to 180°C (fan 160°C).
3. Roast by weight for your preferred doneness.
4. Rest, loosely covered, for 15–20 minutes before carving.

How to tell it's cooked

• Use a thermometer before resting: pink about 55°C, medium about 65°C, well done about 72°C
• The temperature rises a few degrees as it rests
• Juices run pink for medium, clear for well done

Times by size

Food safety: A whole leg of lamb can safely be served pink in the middle once the outside is well browned. Rolled or boned-and-rolled joints, and any lamb mince, must be cooked all the way through to 75°C. Rest before carving and cool leftovers quickly.