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How Long to Cook a Leg of Lamb — Roast Time Calculator

Leg of lamb is one of the most impressive and most straightforward large roasts you can cook — it's incredibly forgiving, benefits from simple seasoning (garlic, rosemary, lemon), and pairs well with wine-based pan sauces. A bone-in leg of lamb runs 6–8 pounds and takes 1.5–2 hours at 325°F for medium-rare. A boneless butterflied leg, being flattened, cooks significantly faster at high heat (400°F, 40–55 minutes) and is ideal for the grill. Enter your leg weight and method for precise timing.

Most lamb enthusiasts prefer medium-rare (130–135°F) for leg of lamb. At medium-rare, the flesh is rosy and the fat has fully melted into the meat. Well-done lamb (160°F+) is noticeably drier and less flavorful — the excessive fat that makes lamb special renders out. Rest 15–20 minutes for a large leg before carving.

Frequently Asked Questions

What internal temperature should leg of lamb reach?
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.
How long does a bone-in leg of lamb take to cook?
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.
How do I know when lamb is done?
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.

Frequently Asked Questions

How long to cook a 7 lb leg of lamb at 325°F?
A 7-pound bone-in leg of lamb at 325°F: approximately 1.75–2.25 hours (15–20 minutes per pound) for medium-rare (130–135°F). Check temperature at 1.5 hours. Pull at 125°F to account for 5–10°F carryover during the 15–20 minute rest. Boneless legs of the same weight cook faster — plan 15 minutes per pound at 325°F.
What temperature should leg of lamb be cooked to?
Leg of lamb doneness temperatures: rare 125°F (red, very soft), medium-rare 130–135°F (rosy, recommended), medium 140–145°F (pink, still moist), medium-well 150°F (slightly pink), well-done 160°F+ (gray, drier). Unlike beef, lamb's fat has a higher melting point — at medium-rare it has fully rendered and coated the fibers. Medium-rare to medium is strongly preferred by most lamb cooks.
How many people does a leg of lamb feed?
A bone-in leg of lamb: 1 lb per person (a 7-lb leg feeds 6–7 people). Boneless: 3/4 lb per person (a 5-lb boneless leg feeds 6–7 people). Include a 10–15% buffer for large appetites or second servings. For Easter or Passover with many sides and appetizers, a 7-lb bone-in leg easily feeds 8 people.

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