Lamb Leg Cook Time Calculator — Roast Timing by Weight

USDA minimum for lamb is 145°F (63°C) with a 3-minute rest. However, most chefs serve lamb at 135°F (medium rare) for the best flavor and tenderness. At 145°F it's medium. Well done at 165°F is safe but often considered overdone.

At 325°F, a bone-in leg takes roughly 18–22 minutes per pound for medium rare. A 5-lb leg takes about 1.5–2 hours. Boneless legs cook 15–18 minutes per pound and more evenly. Always verify with a meat thermometer.

Insert a meat thermometer into the thickest part away from the bone. For medium rare, pull at 125°F — it will rise to 135°F during the 20-minute rest. The meat should be deeply pink inside but not raw-looking.