Explainer
Does a slow cooker waste electricity?
No, a slow cooker is one of the most energy efficient ways to cook, because it uses a low wattage heating element, little more than a light bulb on its low setting, and although it runs for hours, the total energy is usually less than cooking the same dish in an oven.
By the Lush Editorial Team·Researched & Compared
No, a slow cooker does not waste electricity; it is actually one of the most energy efficient ways to cook. Although it runs for many hours, which makes people assume it must use a lot, it draws very little power, especially on its low setting, where the element uses not much more than a bright light bulb. Because energy use is power multiplied by time, a low power appliance running for a long time still uses a modest total, usually less than cooking the same dish in a conventional oven for a shorter time. The slow cookers in our best slow cookers guide are among the cheapest appliances to run for a full meal.
It draws very little power
The key fact is that a slow cooker is a low wattage appliance. It cooks by gently heating food over a long time, so its heating element is small and draws only a little power, far less than a hungry appliance like an oven, kettle, or microwave. On the low setting in particular, the draw is very modest, comparable to a light bulb or two. This low power is the whole reason it can be left on safely for hours: it is not pouring energy in, but trickling a gentle heat. So the long running time is offset by how little it uses at any moment.
Long time, low total
The thing that confuses people is the running time, but energy is power multiplied by time, and a small power over a long time can still be a small total. A slow cooker drawing a little power for eight hours can use less total energy than an oven drawing a lot for one or two hours to cook the same stew. The oven also heats a large cavity and loses heat, while the slow cooker heats just its small insulated pot. So although the slow cooker runs far longer, its gentle draw means the total energy for the meal is usually lower, not higher, than the faster but hungrier oven.
Insulated and sealed
A slow cooker is also efficient because it is insulated and lidded. The ceramic pot and the lid trap heat and moisture, so once it is up to temperature the element only needs to supply a little heat to keep it there, and not much escapes. This is unlike an oven, which heats a big air space and loses heat whenever opened, or a stovetop pot that vents steam and heat continuously. The slow cooker’s contained, insulated design means the modest energy it uses mostly goes into the food and stays there, which is part of why it cooks so economically over its long run.
Compared with the oven
For the kind of dishes a slow cooker makes, stews, braises, soups, and tough cuts cooked long and low, it is generally cheaper to run than the oven. An oven cooking a casserole for a couple of hours draws a lot of power and heats a large cavity, while the slow cooker does the same job with a trickle of power in its small pot. Even over many hours, the slow cooker usually wins on total energy. It also does not heat up the kitchen the way an oven does, which can be a bonus in summer. So for its intended dishes, the slow cooker is the thriftier choice.
Keeping it efficient
A slow cooker is already efficient, but a couple of habits help. Resist lifting the lid during cooking, since each peek lets out heat and makes the element work to recover, lengthening the cook; the lid should stay on until near the end. Match the cooker size roughly to the amount you cook, so you are not heating a large pot for a small meal. Use the low setting for long, gentle cooking where you can, and the dish will still cook beautifully while sipping power. Beyond that, there is little to do, because a slow cooker’s low draw makes it inherently economical.
The short answer
So a slow cooker does not waste electricity; it is one of the most economical ways to cook. It draws very little power, on low not much more than a light bulb, and although it runs for hours, the total energy is usually less than cooking the same dish in an oven, because its gentle draw and insulated, lidded pot keep energy use low. For stews, braises, and tough cuts cooked long and slow, it is the thriftier choice, and the only real tip is to keep the lid on so it does not have to work to recover lost heat.
Common questions
Does a slow cooker use a lot of electricity?
No, very little. A slow cooker is a low wattage appliance, drawing only a little power, on the low setting not much more than a bright light bulb. Although it runs for hours, energy is power multiplied by time, so a small draw over a long time still adds up to a modest total, usually less than cooking the same dish in an oven. It is one of the most economical ways to cook.
Is it cheaper to use a slow cooker or an oven?
Usually a slow cooker, for the stews, braises, and tough cuts it is made for. An oven draws a lot of power and heats a large cavity for a couple of hours, while a slow cooker uses a trickle of power in its small insulated pot, so even over many hours its total energy is generally lower. The slow cooker also does not heat up the kitchen the way an oven does, which can be a summer bonus.
Does running a slow cooker all day cost a lot?
No. Because its element draws so little power, even a full day of slow cooking uses a modest amount of energy, often less than a shorter oven cook of the same dish. The long running time sounds expensive but is offset by the very low draw, and the insulated, lidded pot keeps heat in so the element only tops up gently. The exact cost depends on your rate, but it is one of the cheaper ways to cook a meal.
Why is a slow cooker energy efficient?
Because it combines a low wattage element with an insulated, lidded pot. It cooks gently with a small draw, and the ceramic pot and lid trap heat and moisture, so once hot the element only supplies a little heat to maintain it and not much escapes. Unlike an oven that heats a big air space or a stovetop that vents steam, the slow cooker's contained design puts its modest energy into the food and keeps it there.
How can I make my slow cooker use even less electricity?
It is already efficient, but keep the lid on during cooking, since each peek lets out heat and makes the element work to recover, lengthening the cook. Match the cooker size to the amount you cook so you are not heating a large pot for a small meal, and use the low setting for long gentle cooking where you can. Beyond that, its low draw makes it inherently economical with little else to do.