In the BestReviews test kitchen, we put our slow cookers through a 12-hour test regimen.

Each model was loaded with the ingredients for a savory pot roast with orange.

As the meat cooked, we assessed four performance categories: temperature, finished dish, “keep warm” function, and mobility. We then chose the top five cookers that you can find in our product list at the top of the page.

A slow cooker must be able to keep finished food warm without overcooking it.

The ideal temperature range for keeping foods warm is between 135°F and 155°F.

We tested each unit's temperature at the one- and two-hour mark after the machine switched (automatically or manually) to “Keep Warm" to see if it adhered to our ideal.

Slow cookers prepare foods by braising them. Braising is the slow, low-temp method of applying heat to break down tough meat fibers and weaken vegetable cell structures.

The ideal result: moist meat and soft vegetables.

A slow cooker’s temperature shouldn’t rise above approximately 180°F. Otherwise, the outside layer of meat will overcook to the point of stringy, tasteless dryness, and the inner portion will not have cooked long enough to attain its ideal creamy softness.

In the BestReviews lab, we obtained temperature readings at the following intervals: one hour, two hours, four hours, six hours, and nine hours from the start.

We noted the pace at which each product heated up and what temperature it stayed at during the cooking portion of the test.

After the test period, we checked the meat and other ingredients for the desired fork tenderness.

Each cut of beef was considered done at an internal temperature between 155°F and 170°F.

Where different parts of the cut registered at different temps, we tested for doneness by pulling apart meat fibers with a fork.

We assessed the appearance of each pot roast by looking at the color of the beef, outside and in, and the condition of the accompanying ingredients.

Perfectly braised beef is dark on the outside and pink on the inside.

The taste of each finished dish was rated based on mouthfeel, texture, and whether the dish presented a pleasing combination of flavors.

Once a dish is prepared in a slow cooker, the unit is often moved to another location for serving, such as a table or buffet.

We tested each unit for handle sturdiness, housing temperature, lid integrity, and whether liquids were prone to leak from the insert when moved.

We also considered other features and functions.

For example, some models include the ability to brown or sauté food before slow cooking.

Slow cookers range in size from 1 ½ to 8 ½ quarts. Choose the right size to fit your household.

• In general, if you’re cooking for one to three people, a four-quart model works well.

• For a family of four, opt for a four- or five-quart slow cooker.

• If you routinely cook for larger groups, look for a slow cooker with at least a six-quart capacity.

Most slow cookers are either round or oval in shape. Both shapes work well, but the best option for your kitchen depends on what meals you like to prepare most often.

If you usually cook stews, soups, or beans, both round and oval slow cookers would suit your recipes. However, if you mainly use your slow cooker to prepare whole chickens, ribs, brisket, or other large cuts of meat, an oval shape would likely be the better option.

It’s important to keep the lid on a slow cooker when you’re preparing a meal, so a clear glass lid is best.

A glass lid will allow you to check on the progress of your food without actually removing it.

Plastic and other opaque lids don’t allow you to look inside during cooking, so they’re best avoided.

A slow cooker’s insert is the removable pot that you mix your ingredients in.

Most inserts are made of ceramic or porcelain, but some slow cookers have a metal cooking pot.

These materials all conduct heat well, though ceramic and porcelain are usually easier to clean.

The exterior of a slow cooker often gets hot while in use, but you want to make sure that the handles never do.

Look for a model with large handles that stay cool and are sturdy so you can easily move the slow cooker to serve dinner.

Some slow cookers feature only a manual dial or knob control that allows you to set the appliance to low, medium, or high. They aren’t equipped with timers, so you must keep an eye on your meal and turn the cooker off when necessary.

Other slow cookers are equipped with programmable controls. Not only can you set the appliance to low, medium, or high, you can also set a timer so the slow cooker turns off at a specific time. These slow cookers usually have a “keep warm” setting as well, so your food won’t be cold if you get home after it has stopped cooking.

Depending on how you plan to use your slow cooker, you may want to choose a model equipped with other cooking settings, such as those for browning, sautéing, roasting, or steaming.

Slow cookers with these extra settings are usually more costly, but if you’re making a more involved dish, they can save you from having to clean multiple pots and pans at the end of the night.

Slow cookers are available at a variety of price points.

In general, you can expect to pay anywhere between $15 and $150, depending on the size of the cooker and its features.

• For a basic, mechanical slow cooker, expect to pay $15 to $40.

• For a higher-end, programmable slow cooker, you’ll likely pay between $50 and $150.

• Preheat your slow cooker before adding your ingredients. Giving it 20 minutes or so to warm up before you toss in your ingredients can make a big difference in the end product.

• It’s best to use fatty, tougher meats, such as short ribs, pork shoulders, chuck roasts, and lamb shanks in your slow cooker. Lean meats such as pork tenderloin can dry out.

• Don’t overcrowd a slow cooker. Only fill it half or two-thirds full.

• Dairy products usually break down in a slow cooker, so if you’re adding milk, yogurt, sour cream, or other dairy products, do it in the last 15 minutes.

• Don’t lift the lid off your slow cooker to check on your meal. The heat will escape and slow down the cooking time. Only check on your meal in the last half-hour or so of cooking.

Q. Is it safe to leave a slow cooker on while I’m out of the house?

A. Most slow cookers are designed to be safe if they’re left on unattended on your counter. To be cautious, though, check that nothing is touching your slow cooker before you leave.

Q. What features make a slow cooker easier to clean?

A. Most slow cooker inserts are removable to make cleaning easy. However, for the easiest cleaning, opt for a model with a dishwasher-safe insert.

Q. Can I take a slow cooker on the go?

A. You can prepare a meal in a slow cooker and then bring it with you to a potluck dinner so it stays warm. Look for a model with a locking lid so you can be sure it’s sealed completely. A retractable cord can also make a slow cooker more portable.