How Long to Cook a Roast in a Slow Cooker

How Long to Cook a Roast in a Slow Cooker (Image: grandriver/iStock/GettyImages)

Looking for a hands-off way to cook rich, delicious pot roast? Your slow cooker is your best friend. The low heat point lets the roast cook slowly so the fats break down to make it tender and moist. Figuring out how long to cook a roast in a slow cooker comes down to several factors, including the type and size of the roast.

Heat Settings and Cooking Times

Have you ever noticed that most slow cooker recipes give two vastly different cooking times – one for the low setting and one for the high? That's because there's a significant difference in temperatures between the settings. The low setting is roughly 190 degrees Fahrenheit and the high setting is 300 degrees Fahrenheit.

Slow-cooker pot roast recipes generally recommend the low setting. The lower temperature gives the meat longer to cook and get tender as the fat melts. A 3-pound to 4-pound beef roast needs about 8 hours of cooking time on the low setting. The same piece of meat needs a little over 5 hours on the high setting.

Variety of Roast

Fatty, tough roasts like the chuck roast or round roast work best for the slow cooker. They get more moist and tender as they cook unlike leaner roasts, which tend to dry out. You can cook a chuck roast or other fatty, tough roasts for longer, and the results only get better as the connective tissues break down in the meat.

Whether or not the roast has a bone can impact cooking time. Bone-in roasts may need a little more time to cook. The bone tends to slow the cooking time since it takes longer to heat up than the surrounding meat.

Size and Shape of Roast

It's logical that larger roasts need more cooking time, but it's not just the weight or size that matters. The shape can also influence cooking time.

Imagine two roasts that both weigh 3 pounds. One is wide and flat, and the other is as thick as it is wide, almost round in shape. The wide, flat roast cooks faster because it's not nearly as thick and can cook through faster. The heat has to go through a lot more meat to reach the center of the thicker roast, which increases the cooking time.

Fullness of the Slow Cooker

You can't have pot roast without potatoes, carrots and onions. However, your slow cooker can fill up quickly with all those goodies, especially if you choose a large roast. An overly full slow cooker means everything takes longer to cook.

Try to keep your slow cooker no more than half to two-thirds full for shorter cook times. If you pack it to the top, expect your roast to take longer to cook. Buying a larger slow cooker helps shorten cooking times for those larger-roast meals.

Opening the Lid

It's so tempting to check out the roast yourself or smell the cooking food. However, each time you peek, you let the heat and steam out of the slower cooker. That lowers the temperature and increases the cooking time. You may be adding as much as 15 to 20 minutes to the total cooking time each time you open the lid.

The tightness of the lid can also impact the cooking time. Some slow cookers have a rubber seal along the lid that helps lock in the heat and steam. That can shorten the cooking time.

Testing for Doneness

The most reliable method to check for safe food doneness is internal temperature measures with a meat thermometer. Look for an internal temperature of at least 145 degrees Fahrenheit for beef and pork roasts. Another sign of doneness is a chuck roast that falls apart or is fork tender.

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