How to cook a leg of lamb

Whether it’s a Sunday roast, a midweek slow cook or a festive dinner for family and friends, a roast leg of lamb is a delicious and versatile joint of meat that will wow your guests with minimal effort.

In our expert guide, we cover everything from how long to cook the meat and what size leg to buy, to how much lamb you’ll need per person. Cook it properly and you’ll have a melt-in-the-mouth roast that everyone will love.

Keep scrolling for our step-by-step recipe and discover which herbs and spices will enhance the flavour of your lamb.

How to cook a leg of lamb

1. Take the lamb out of the fridge for at least an hour before cooking so it can get to room temperature.
2. Set the oven to 220°C/200°C fan/gas mark 7.
3. Weigh the meat to calculate the cooking time – it’s approximately 20 minutes per 450g/lb, plus an extra 20 minutes if you like your lamb medium done.
4. Drizzle with olive oil and rub all over the meat before seasoning generously with salt and pepper.
5. Place the lamb into a roasting pan and put it into the preheated oven.
6. Cook for 20 minutes before turning the oven down to 190°C/170°C fan/gas mark 5 and continuing to cook until it’s done.
7. Take it out of the oven, loosely cover with foil and let it rest for around 15 to 20 minutes before carving and serving.

What is the cooking time for a leg of lamb?

Once you know the weight of the meat, you can work out roughly how long it will take to cook. The total cooking times for a leg of lamb (medium) are as follows:

• 750g 1 hour 5 minutes
• 1kg 1 hour 15 minutes
• 1.5kg 1 hour 40 minutes
• 2kg 2 hours 5 minutes
• 2.25kg 2 hours 30 minutes
• 2.50kg 2 hours 50 minutes
• 2.75kg 3 hours

If you prefer your meat well done, you can alter the cooking times to 30 minutes per 450g/lb, plus an extra 30 minutes.

Make sure you also check the cooking times listed on the packaging, or ask the butcher if you’re not buying from a supermarket.

Cooking times can also vary depending on how well your oven sticks to its temperature. In our tests, we've found some ovens that overheat by 30ºC more than the set temperature, which is enough to turn a perfectly tender joint into a crispy mess.

If you're looking to replace your oven, take a look at our built-in oven reviews, freestanding cooker reviews and range cooker reviews.

Does lamb leg get more tender the longer you cook it?

Lamb will become tender when cooked using a slow cooking method. If you opt for a shorter, high-heat approach, it will need careful monitoring to ensure the lamb stays succulent.

Remember that cuts with more fat – shoulder, shank and leg, for example – are better suited to slow cooking. If lamb is cooked steadily over a prolonged period, this allows time for the connective tissue in the meat to break down.

What size leg of lamb do I need?

If you’re trying to calculate how much you’ll need to cook for any guests, a good rule of thumb is 400g plus 200g per person. Below is an idea of roughly what weight you'll need to feed everyone at your dinner table.

• 750g-1kg Serves two
• 1-1.5kg Serves four
• 1.5-2kg Serves six
• 2.25-2.75kg Serves eight

Where to buy a leg of lamb

Lamb is widely available from nearly every supermarket or butcher in the UK and Ireland. If you're not sure where to go, see our round-up of the best and worst supermarkets.

• Aldi sells half legs of fresh lamb, starting from £12.49/kg. It doesn't offer home delivery, but you can click and collect groceries from selected stores. 
• Asda sells its own-brand lamb, with a half leg costing £12.98/kg at the time of writing. It offers same-day or express home delivery (typically around £8.50). For click and collect, many stores offer a same-day express collection slot (within 4 hours) with a £3.50 fee.
• Morrisons offers a selection of fresh whole lamb legs starting at around £15.70/kg. Morrisons’ online delivery charges typically range from around £1.50 to £6, depending on your location, order value and slot time.
• Sainsbury's stocks a wide range of own-brand options costing from £15.70/kg for a whole leg.
• Tesco has its own-brand options starting from £16/kg for a half leg and £15.70/kg for a whole leg.

Crown your roast by reading our advice on how to make Yorkshire puddings.

What to add to a leg of lamb

While a well-cooked leg of lamb will taste fantastic on its own, fresh herbs and the right accompaniments can add a delicious depth of flavour. 

Here are some of the best herbs, spices, sauces and condiments to pair with lamb:

• Aioli A creamy, garlic sauce that will taste best served with lamb and potatoes.
• Baharat seasoning or curry powder Use as a dry rub or mix into stews or other wet dishes.
• Black pepper Create a mustard and black pepper crust, pair with a black pepper sauce or simply season with black pepper before roasting.
• Chimichurri Made of finely chopped parsley, minced garlic, olive oil, oregano and red wine vinegar, fresh and vibrant chimichurri sauce can be served alongside lamb or used as a marinade before cooking.
• Cumin Cover your lamb with cumin (ground or seeds) before cooking to create a crust.
• Curry Lamb goes perfectly in a curry, particularly a rogan josh, jalfrezi or bhuna.
• Garlic Slather garlic butter or stud garlic cloves into the meat before cooking.
• Gravy Use the juices from the cooked lamb to make a homemade gravy.
• Gremolata Garnish with this tangy green sauce made up of chopped parsley, lemon zest and garlic.
• Mint and mint sauce Pair roast lamb with a mint sauce or jelly, sprinkle fresh mint leaves into a side salad or make a mint marinade.
• Mustard Rub English or wholegrain mustard into the lamb before roasting to leave a spicy crust.
• Oregano Mix with olive oil, garlic, salt and pepper and rub over the meat before roasting.
  
• Rosemary The classic combination. Stud the sprigs into the meat before cooking or add to a marinade or butter.
• Tomato relish Serve as a condiment with any lamb dish.
• Thyme Simply add the stalks and all to the pan when cooking.
• Yoghurt/tzatziki Serve on the side, in a gyro or drizzled over sliced lamb.

Best red wines: serve your lamb with one of our top-rated picks for a perfect pairing.

How to slow roast a leg of lamb

To slow roast a leg of lamb, all you need to do is lower the heat and lengthen the cooking time. We also advise covering the lamb with foil to help the meat retain its moisture.

1. Take the lamb out of the fridge for at least an hour before cooking so it can get to room temperature.
2. Set the oven to 170°C/140°C fan/gas mark 3.
3. Weigh your lamb to calculate the correct cooking time – add around three hours to the cooking times listed above. For example, five to six hours for 2kg.
4. Drizzle with olive oil and rub all over, before seasoning generously with salt and pepper.
5. Place the lamb into a roasting pan, cover loosely with foil and put into the preheated oven.
6. Remove the foil 45 minutes before it’s done so the meat can brown.
7. When the meat is cooked to your preference, take it out of the oven, loosely cover it with foil and let it rest for 15 to 20 minutes before carving and serving.

Alternatively, use one of our best slow cookers.

Can you air fry a leg of lamb?

Yes, you can air fry a half leg or mini leg of lamb if it fits comfortably in your air fryer. A smaller joint usually works best.

A recipe by BBC Good Food suggests cooking garlic and oregano lamb leg in an air fryer and serving it with crispy new potatoes. To try it for yourself, follow these steps:

1. Take the lamb out of the fridge around 30 minutes before cooking. Make small incisions in the meat and slide in slivers of garlic, then rub with olive oil, chopped oregano, salt and pepper.
2. Heat your air fryer to 200°C, then place the lamb in the basket, pour over half the lemon juice, and arrange seasoned baby new potatoes around it.
3. Air fry for 15 minutes, then lower the temperature to 180°C and cook for another 45 minutes, turning the lamb halfway through.
4. Transfer the lamb to a warm plate, cover loosely with foil and rest for 10 minutes. You can also sprinkle the potatoes with grated cheese and lemon zest, then air fry for 5–8 minutes more until golden and crisp.
5. Drizzle the lamb with any resting juices, garnish with a sprig of oregano and serve with lemon slices.
   

Check in with our guide to the best air fryers to see which models we recommend.

More roast lamb recipes

• BBC Good Food's roast leg of lamb recipes – many of these recipes include anchovies for a salty twist, and several of them can be cooked in under two hours. You can also check out leftover lamb recipes to ensure that none of your roast goes to waste.
• Jamie Oliver's roast leg of lamb recipes – Jamie uses a marinade made up of rosemary, garlic, olive oil and lemon zest to flavour the lamb and advises cooking the joint on the hot bars in the oven rather than in a roasting pan.
• Nigella Lawson's roast leg of lamb recipes – like Jamie, Nigella rubs a leg of lamb with a marinade. But she uses rosemary, oregano, lemon, orange, garlic, olive oil and salt, which once cooked will form a soft, fresh crust on the top of the joint. The recipe also advises cooking the meat in half an inch of water.
• Mary Berry's roast leg of lamb recipes – this crowd-pleasing recipe takes around five hours, so you’ll need to start earlier in the day. Seasoned with garlic, paprika and thyme, the lamb is then cooked with ratatouille-style vegetables and covered with foil to keep it moist.

See our round-up of all our best food and drink.