Cooking times for roast lamb vary according to the size of the roast, how well done you like your lamb and cooking temperatures. Recommended cooking temperature for leg of lamb is 325 degrees F and for crown roasts and rib roast is 375 degrees F. The cooking times listed here are based on these recommended temperatures. Use the approximate cooking times, in combination with a meat thermometer, to determine when the meat is done. The meat will continue to cook for a few minutes after being removed from the oven, so remove the lamb from the oven at a temperature a few degrees less than you prefer.


Doneness

The degree of doneness of roast lamb can be determined by firmness of touch, appearance of meat and by the internal temperature. Internal temperature is the best way to determine when the lamb is done. On a meat thermometer, medium rare lamb registers 145 degrees F, medium is 160 degrees F, and well done is 170 degrees F.

Leg of Lamb

A whole leg of lamb, roasting at 325 degrees F, will take approximately 20 minutes per pound for medium rare, 25 minutes per pound for medium, and 30 minutes per pound for well done.

Leg Shank Half

A leg shank half weighing approximately 3 to 4 pounds, roasting at 325 degrees F, will need to roast 25 to 40 minutes per pound for medium rare, 30 to 40 minutes per pound for medium, and 35 to 45 minutes per pound for well done.

Leg Sirloin Half

A leg sirloin half weighing approximately 3 to 4 pounds will need to roast 25 minutes per pound for medium rare, 35 minutes per pound for medium, and 45 minutes per pound for well done at 325 degrees F.

Crown Roast

An unstuffed crown roast should be roasted at 375 degrees F. Allow 25 minutes per pound for medium rare, 30 minutes per pound for medium and 35 minutes per pound for well done.

Rib Roast

A rack of lamb or rib roast should be roasted at 375 degrees F. Allow 30 minutes per pound for medium rare, 35 minutes per pound for medium and 40 minutes per pound for well done.

References and Resources

Lamb Cooking Times