The Best Slow Cookers

A slow cooker promises to be a little fantasy grandmother who sits in the kitchen all day cooking for you, but use the wrong cooker and that dream could fizzle. A cooker might run hotter than expected, drying out the food or turning it mushy, or slower than you want, so dinner isn’t ready when you are. Then there can be issues with hot spots, which make food cook unevenly. And what if operating your machine is so confusing that you have to pore over the manual each time you use it?

A well-designed slow cooker excels in covered, moist-heat cooking, also known as braising. This technique is beneficial for meat—usually tough, cheap cuts that tenderize through long, gentle cooking. When connective tissue, which is made mostly of collagen, is cooked beyond 140 degrees, it begins to break down into gelatin, the protein that makes for tender meat. Collagen breaks down most efficiently in a moist environment at temperatures around 200 degrees. This lower-than-boiling temperature range is also good for developing deep, complex flavors in soups, stews, and sauces. 

Most slow cookers come with two settings: low and high. The two settings give cooks flexibility: You can either cook for a shorter span on high or about twice as long on low. Generally the choice is about convenience, not flavor or texture, though delicate foods often require the low setting. Frequently we have found that slow cookers reach the same final temperature on either setting but take longer to do so on the low setting than they do on the high setting. 

 We wanted a slow cooker that would deliver a properly cooked meal and be simple and intuitive to use. Previous testing taught us that glass lids were a must so that you can see progress without opening the lid, which lets heat escape and slows down cooking. We also prefer oval- and rectangular-shaped crocks, which can accommodate large roasts; provide abundant surface area to successfully slow-cook rice, grains, and beans; and generally offer more versatility than round crocks. A generous 6- to 7-quart stated capacity was a must—the same capacity as the Dutch oven we’d otherwise use for similar tasks. Few slow cookers actually hold as much as their stated capacity, but we’ve found them to be adequate for all tasks regardless. 

There are two main styles of slow cookers, as we found out when we dismantled a duplicate set of cookers with the help of Gregory Thiel, a postdoctoral associate in mechanical engineering at the Massachusetts Institute of Technology. 

Traditional slow cookers have thick, heat-retaining ceramic vessels that absorb and transmit heat gradually. They’re warmed by a thin heating element strip made of nickel and chromium (or “nicrome”) that wraps around the vessel like a belt. When the cooker is on, this wire heats up more or less powerfully depending on the wattage and the setting. Other models feature a thin, nonstick-coated metal crock (usually aluminum) that sits on an electric heating element in the base that acts like an enclosed burner. 

There are pros and cons to each style. Metal crocks are lightweight and more durable, unlike ceramic crocks, which can crack if dropped or sharply struck. The metal crocks also let you sauté and brown food right in the crock, no separate skillet needed. You can’t brown or sauté in ceramic crocks; you must brown food in a skillet on the stove and transfer food to the slow cooker. 

While it’s convenient to sauté food right in the cooker, it’s important to note that metal models typically slow-cook much faster than ceramic models: first, because they are often starting hot after sautéing, and second, because thin metal heats up faster and more efficiently than thick ceramic, especially when the entire metal crock bottom rests on a large heating element. As a consequence, with a metal crock, if you don’t pay close attention, you can easily overcook food. It’s important to check for doneness much earlier than indicated in most recipes, which are usually developed in ceramic slow cookers. 

• Digital, Programmable Controls: We much preferred digital programmable cookers, which let us choose our desired cooking time and high or low setting to cook our meal, showed us a countdown to doneness, and also automatically switched to “warm” when the preset cooking time was up. 
• Simple, Intuitive Controls: A few models were a pleasure to use, with controls that were unambiguous and buttons that clicked satisfyingly and lit up when pressed and indicated that cooking had started. 

• Internal Temperature Sensor and Control: Our temperature tests revealed that better slow cookers had internal temperature sensors and controls. That meant that they cooked more gently and successfully than slow cookers without temperature controls (which simply keep heat fully on until food boils at 212 F, with predictably rubbery, overcooked results). Cookers with sensors kept food at a braising temperature, just below boiling, so the foods cooked gently and became tender while retaining their juiciness. Note: You can’t see this feature when you’re shopping, but our testing results (using a temperature probe suspended in water in the slow cooker over hours of cooking on low and high settings) clearly indicated which models had internal controls and heated gradually to cook more gently and successfully. 
• Large, Stay-Cool Handles: Crocks with handles that were easy to grasp securely and stayed cool were easier to use. 
• For Traditional Models—Good Insulation: Traditional slow cookers can sometimes heat unevenly, with hot spots around the belt-shaped heating element that surrounds the ceramic crock. When we dismantled all the crock pots, we found that the traditional slow cookers that performed best had thick, heat-resistant padding and foil heat shields packed inside. The other traditional models were empty except for the heating element. The insulation buffered the crocks from contact with the heating elements, preventing hot spots and promoting even cooking. It also explained why some of those models, including one of our favorites, tended to run a bit slower.

• Attached Temperature Probe: One model had an attached probe that accurately measured the temperature of food cooking inside the slow cooker. While it’s possible to slow-cook successfully without this feature, we appreciated that the probe let us monitor food safety and cooking progress without opening the lid. This is important because slow cookers typically cook very gently, and every time you open the lid to stir or check food, you lose considerable heat, which lengthens the cooking time. The model that came with this temperature probe had three ports in the lid with tight silicone gaskets that kept heat in but allowed us to insert the probe in different locations as needed. The probe stored neatly in the handle when not in use, so we didn’t risk losing it. 
• Latching Lids and Silicone Gaskets: Since we often take a slow cooker to a potluck or other occasion, we liked models that had latching lids and silicone gaskets around those lids, which helped prevent leaks in transit. 
• “Hold Temperature” Feature: One model can hold food at your desired temperature for up to 24 hours. This feature lets you use the slow cooker to reheat leftovers, as a fondue pot, or as a yogurt maker. While the manufacturer claims this also allows you to use it as a sous vide cooker, it lacks a propeller to circulate water around the food, which you’d find with dedicated sous vide immersion circulators. 

• Analog Controls: Unless you really want a very simple, inexpensive slow cooker and you plan to be around while it’s cooking, avoid models with analog controls (that is, simple knobs that switch the cooker to on, off, high, low, or warm). These may seem less confusing than digital controls, but they don’t indicate progress (showing remaining cooking time), and they won’t switch over to keep warm when cooking is done, so you run the risk of overcooking your food. 
• Overcomplicated Displays: You really shouldn’t need the manual after the first time you use a slow cooker. We wanted intuitive controls, but several models had so many buttons with such confusing layouts that our testers couldn’t tell if they’d set them correctly or even whether they were on.