Lamb leg roast is a delicious dish that many people enjoy. However, getting lost in the confusion of lamb leg roast cooking time is easy.
Cooking time varies depending on the size of your lamb and the cooking method you use (oven or barbecue). Knowing how long it needs to cook can be tricky, so we have created this guide for you.
This blog post will explore the best ways to cook lamb leg roast, depending on your preferences. We will also discuss how long you should expect each method to take. So, you can confidently prepare your meal without worrying if it will be done in time for dinner.
A leg of lamb roast is a cut of meat that comes from the upper portion of the back legs of an animal. It’s also known as a saddle or hindquarter and can be cooked in many different ways.
Why Do You Choose the Lamb Leg?
The lamb leg roast is a versatile piece of meat that can be cooked in the oven, barbecued, or even smoked. And it’s delicious.
If you want a simple, lean roast lamb cut, go for a leg of lamb. You can buy a whole leg that is bone-in leg, part bone-in, or boneless.
A whole leg makes a beautiful centerpiece and retains flavor from the bone. A boneless leg is easier to serve and carve, or you can also choose a part-boned leg in the middle.
Butterflied lamb leg roast is a leg of lamb with the leg bone removed, and the meat opened out to form a butterfly shape. This cut is often used for barbecuing. But it can also be used to cook a roast because the meat is flat and cooks quickly.
A whole leg of lamb is usually about 2-2.75kg and will serve 6-8 people. If you cook for a smaller group, get the half leg instead.
If you are cooking a boneless lamb roast, leg, or shoulder, it should be 225g per person. For 6 people, the meat should weigh between 1.5 – 2kg. Buy a larger piece of meat than you need because the meat will shrink when it cooks.
Defrost your meat in the fridge or a cool room below 10–15C rather than at room temperature so that the outside remains cold. It is imperative to ensure that poultry is fully defrosted before cooking.
Add seasoning
There are many ways you can add to and enhance the flavor of your roast lamb. Start with something simple like a leg of lamb seasoned with rosemary and garlic.
There are many ways you can add to and enhance the flavor of your roast lamb. Start with something simple like rosemary and garlic.
If you like your lamb plain and simple, sprinkle it with salt before you cook it.
Get cooking
Preheat the oven or barbecue to the recommended oven temperature for your cut.
Put the meat on the roasting rack.
Follow the recommended roasting time for your cut’s weight.
Check the lamb roast internal temperature with a meat thermometer or instant-read thermometer.
Remove the cooked lamb roast before it reaches the final temperature as it continues to cook while resting.
Baste the lamb
Baste the lamb 2 or 3 times while it is cooking. Basting means spooning the juices from the roasting tin back on the cooking meat. Tilt the roasting container out of the oven rack so that all fat and fluids collect in one corner. Remember to shut the oven door when you baste.
Rest the meat
Once you cook the meat, put it in a warm place covered with tented foil for the time listed in the calculator. This will make it juicier and easier to carve.
Roast Lamb Cooking Time Calculator – How to Determine Lamb Leg Roast Cooking Time?
Raw Lamb in Oven. Credit: canva
Cooking time for the lamb roast is the time it takes to cook a roast. It can vary depending on the lamb cuts, your cooking method, and how well done you want your meat to be.
Roast Lamb Cooking Time and Temperature Guidelines
Weight per 500g (approximate)
Internal temperature goal
Oven Roast Lamb Cooking Time and Oven Temp
Eye of loin/backstrap, lamb round, topside roasts, mini roast, lamb rump
Oven temp. (NO FAN): 220°C
Rare (58°C): 22 min per 500g
Medium (65°C): 28 min per 500g
Well done (70°C): 32 min per 500g
Rack of lamb, four-rib roast, crown roast
Oven temp. (NO FAN): 200°C
Rare (58°C): 24 min per 500g
Medium (65°C): 33 min per 500g
Well done (70°C): 43 min per 500g
Loin (boned and rolled) easy-carve leg or shoulder
Oven temp. (NO FAN): 180°C
Rare (58°C): 19 min per 500g
Medium (65°C): 26 min per 500g
Well done (70°C): 30 min per 500g
Butterflied lamb leg
Oven temp. (NO FAN): 180°C
Rare (58°C): 12 min per 500g
Medium (65°C): 15 min per 500g
Well done (70°C): 18 min per 500g
Butterflied lamb shoulder
Oven temp. (NO FAN): 180°C
Rare (58°C): 22 min per 500g
Medium (65°C): 25 min per 500g
Well done (70°C): 29 min per 500g
Boneless shoulder lamb cooking time calculator (Boned and rolled)
Oven temp. (NO FAN): 180°C
Rare (58°C): 19 min per 500g
Medium (65°C): 26 min per 500g
Well done (70°C): 31 min per 500g
Barbecue Roast Lamb Cooking Time and Temp
Lamb round, topside roasts, lamb rump
Barbecue temp.: 200°C
Rare (60°C): 20 min per 500g
Medium (65-70°C): 25 min per 500g
Well done (75°C): 30 min per 500g
Rack of lamb
Barbecue temp.: 200°C
Rare (60°C): 20-25 min total (regardless of weight)
Medium (65-70°C): 30-35 min total (regardless of weight)
4Well done (75°C): 40-45 min total (regardless of weight)
Leg or shoulder (bone-in), easy-carve leg, shoulder
Barbecue temp.: 180°C
Rare (60°C): 25 min per 500g
Medium (65-70°C): 30 min per 500g
Well done (75°C): 35 min per 500g
Slow Cooking Time: Slow Roast Leg of Lamb Cooking Time Calculator
Generally, if using a slow cooker, we recommend simmering or slow-roasting lamb at 160–180°C for two hours.
Leg of Lamb Cooking Time Calculator UK
The great thing is that BBC UK provides a roast calculator to calculate the cooking time for various types of meat and different parts of meats, including the leg of lamb.
Simple Guides to Different Sizes of Leg of Lamb Cooking Time
Sliced Lamb Roast. Credit: canva
This simple guide calculates the approximate cooking times using the above roast calculator (medium).
2.5kg leg of lamb cooking time
First brown: 20 mins (at 220°C), then cook: 1 hrs 40 mins (at 180°C), then rest: 30 mins (in a warm place)
1.8kg leg of lamb cooking time
First brown: 20 mins (at 220°C), then cook: 1 hrs 12 mins (at 180°C), then rest: 30 mins (in a warm place)
1.4kg lamb roast cooking time Australia
First brown: 20 mins (at 220°C), then cook: 56 mins (at 180°C), then rest: 30 mins (in a warm place)
1kg leg of lamb cooking time
First brown: 20 mins (at 220°C), then cook: 40 mins (at 180°C), then rest: 30 mins (in a warm place)
500g lamb roast cooking time
First brown: 20 mins (at 220°C), then cook: 30 mins (at 180°C), then rest: 30 mins (in a warm place)
Half leg of lamb cooking time calculator
Depending on the size and weight of the half leg.
How Do You Know When the Lamb Leg Roast is Done Cooking?
When the cooking time is up, use a skewer to check your lamb’s degree of doneness. Stick it into the thickest part of the lamb meat. If it slides in easily, then your cooked lamb leg is done.
If the lamb juices are pink, then it is medium-rare. If the juice is slightly pink, it will be medium. When you want to eat well done, they should run clear. Use a meat thermometer to make sure.
The lamb will be cooked through and falling apart, so you can’t use the words medium, medium-rare, or well done.
Cooking time for the lamb roast is the time it takes to cook a roast. It can vary depending on the lamb cuts, your cooking method, and how well done you want your meat to be.
How long does a leg of lamb take in the oven?
A leg of lamb is browned and then cooked at about 180°C for about 30 minutes to one and half an hour, depending on the size of the meat.
What is the best temperature to cook leg of lamb?
Legs of lamb are usually cooked at around 180°C for 30-40 minutes. The internal temperature should reach 70°C when tested with a thermometer.
What temperature do I cook roast lamb?
You can cook a leg of lamb at any temperature between 140°F and 200°F. You will get better results if you use a meat thermometer to check that the internal temperature has reached 70°F.
Should I cover my leg of lamb with foil?
Yes, this helps retain moisture and keep the meat tender.
How long does lamb take to cook per kg?
First brown for 20 mins (at 220°C), cook for 40 mins (at 180°C), then rest for30 mins (in a warm place).
How long does a 1.5 kg leg of lamb take to cook?
First brown for 20 mins (at 220°C), cook for 40 mins (at 180°C), then rest for 30 mins (in a warm place).
How long does a 1.4 kg lamb leg take to cook?
First brown for 20 mins (at 220°C), cook for 40 mins (at 180°C), then rest for 30 mins (in a warm place).
What temperature is leg of lamb cooked in celsius?
You can cook a whole leg of lamb at any temp between 140°F and 180°F. Using an instant-read thermometer, you’ll get better results by checking that the internal temperature has risen to 70°F.
What is good to season lamb with?
Salt and pepper are the most common seasonings used to flavor lamb. Herbs such as rosemary, thyme, oregano, sage, bay leaves, garlic, onion, and lemon juice may also be added.
Do I cover lamb with foil when roasting?
Yes, this keeps the meat moist and prevents it from drying out during cooking.
