Are Slow Cookers Really Energy Efficient?

slow cookers-do they save energy?Slow cookers, first marketed under the brand name crock-pot, are often recommended for busy cooks. You put in the food, turn it on low, and seven or eight hours later you have a delicious meal. Frugal cooks prefer slow cookers too. But are slow cookers truly energy efficient, as is often claimed?

Apparently, we’ve been misled—even compared to the oven, which is considered an inefficient cooking method. The entire oven has to be heated even for a small item, and little of the heat gets to the food. But the oven does work efficiently by cycling on and off according to the internal temperature via a thermostat. I haven’t tested mine, but online I’ve seen 12-15 minutes of use during a full hour. So while the heating elements use 1000-2000 watts an hour, most of the time they will be off and your usage is only about a quarter of that. A lot depends on your oven, its size, and how often you open it.

Slow cookers, also known by the brand name Crock Pot, don’t usually have a thermostat. It uses a small amount of wattage, but continuously. Doug Cotes over at The Dollar Stretcher calculated that to run his oven for an hour requires 600 watts. He writes:

Our slow-cooker is a large 5-quart brand with a low cooking power of 180 watts and a high cooking power of 250 watts. It’s information you find on the label. . . . the slow-cooker cooks continuously. What that means is if you cook on high with a 250 watt hour element for 4 hours, you use (4 X 250) 1000 watt hours of electricity. If you cook on low with a 180 watt hour element for 8 hours, you use (8 X 180) 1440 watt hours of electricity. No energy savings at my house. If you have a small slow-cooker with a low range that uses a 70-watt element, cooking for 8 hours only uses 560-watt hours of electricity.

Some newer models of slow cookers do have thermostats to regulate the temperature during cooking, in which case the above would probably not apply.

Of course, there are other factors that go into cooking decisions. If you are making a casserole in the oven you can bake bread or roast vegetables at the same time. If you want s hot meal as soon as you get back from work, nothing beats the slow cooker. It’s especially good if you come home at a different time each day. My husband once left a chicken in the slow cooker for three days, and it came out just fine.

Here is a different calculation with the slow cooker coming out way ahead, from the blog Organizing the Four of Us:

The verdict: 3.2 amps used in the slow cooker versus 9.665 amps drawn from the oven OR if you want to compare the figures to your electricity bill the slow cooker used .768 kWs in 8 hours and our oven used 2.320 kWs in the time taken to cook those dear potatoes

Our slow cooker draws .4 amps on the low setting (I use this setting for most of our slow cooked meals). 
.4 amps by 8 hours is a total of 3.2 amps (.768 kWs) used for the duration of our cooking time.
Thanks to reader Gail for bringing it to my attention.
I have noticed that having on the slow cooker increases the temperature of my kitchen, so I don’t like to use it in the summer. If you have a small cooker, be sure to compare costs.

Comparison of advantages of slow cookers vs. conventional ovens:

Advantages of slow cooker

  • Flexibility in the length of cooking time.
  • Can be prepared well in advance and forgotten.
  • Portable: can be removed from the kitchen in hot weather or brought to a hospital or hotel room (if permitted).
  • Easy way to use up leftovers.
  • No need for pre-cooking, although you may want to soak beans or sauté onions.
  • Great variety of recipes for one-pot meals.
  • Can be used creatively for hot cereals, puddings, cakes and more.

Advantages of oven:

  • More room to prepare several items and types of food.
  • Cooks much faster.
  • May use less energy because of quick cooking times, and the thermostat cycles the heating element off and on (see above).

If you are looking for more efficient cooking methods, try a pressure cooker or microwave.


Getting the Most Out of Your Conventional Oven

Don’t Stir the Pot: Make It in the Microwave Instead

Six Low-Tech Kitchen Tools to Save You Time and Money

My Cooking Spreadsheet

Photo credit: Janine


  1. Arg! And here I thought we were being more frugal and energy conscious. It’s still my go to for plan ahead meals.

    I wonder how it compares to having an electric stovetop on, to compare cooking soup.

    Hmm, there seems to be some data that shows that the crockpot is more efficient, I wonder if the measurements take into account the elements cycling on and off. I do know that our oven (that came with the apartment) doesn’t cycle off as often at high temps. It’s probably losing from around the door as best as I can figure.

  2. I love my slow cooker, but probably unlike most Torah-observant cooks I don’t use it for cholent. I’ll stick a brisket in there late at night and sleep peacefully knowing it will be ready in the morning. For me it’s not an energy-saver but a time saver (ironically, taking more time saves me time).

  3. Hannah,
    The only way to tell is to try in real life. Way back when, everyone in our circles were quoting that if you leave your hot water heater (dood, as Benjy is fond of pointing out)on all the time, the water stays hot and then when you use the water it takes less electricity to heat up what’s coming in. So, the wisdom went, if you only turn it on when you need hot water you have to heat up the whole thing and you’re really wasting electricity. The local electrician even verified the logic of it.
    OK, so I left mine on for a who week and wrote down the numbers. Then the next week I went back to turning it off when I didn’t need it. My weekly figure was about 60% of the non-turning off week. I did this for a few weeks and it never got close. So much for common wisdom.

  4. we almost never use ours – even for chulent, I usually prefer to start the cholent in a pot on the stove because it’s easier to make sure it’s cooked before Shabbat and then put it on the platta – we only make chulent once in a while, though – 2-3 times per winter.

  5. Kelli Brown says

    We live for ours. We use it to cook brisket, cholent, chicken, soups, stews, almost everything. We actually have two of them, we use them so much.
    But my real question is – anyone know where to find a pressure cooker in Israel (besides the Knesset)?

  6. When I was working full- and part-time the slow cooker was a lifesaver. Now we mainly use it for cholent, and I made a really yummy brisket for Rosh Hashana in it.

  7. I never got into slow-cookers. No doubt it’s good in the winter if you’ll be out all day, have no electrical problems and need food ready to eat when you get home. Otherwise, I find it efficient to cook for the week and quickly reheat food for dinner.

  8. I was looking to cook green beans and was wondering what was more efficient the crock pot or pressure cooker. When I use the crock pot I put it outside on the back porch. That way I do not heat up the house.

    • Hi Donald! Green beans should only cook for a few minutes, so the crock pot would ruin them. Even with a pressure cooker you’d need to be careful to avoid over cooking, and put water on the cover to stop the cooking after a minute or two under pressure.

  9. Elaine Schiffer says

    We are missionaries in Jamaica. I work about ten hours a day and use the crockpot at least 3 times a week. However, we operate on solar and wind so we have to be careful of the electricity. We can use line power but it costs 3 times what it does in the US. So, my question is, does anybody make one that is more efficient…if they were insulated it would make a big difference. Instead the sides are very thin.

    • Elaine, have you looked into making a solar oven? They cook slowly and don’t require electricity and are fairly simple to make.

  10. Interesting, I use my slow cooker mostly for cholent. So the equivalent oven usage wouldn’t be 1 hour of bake time, but 12 hours. I’d have to do the math to figure out just how much power the oven uses, since it doesn’t take too much to maintain a low temperature for 12 hours.

    Kelli, I got a really great pressure cooker from the Soltam outlet store — 10 liters, really comfortable to use, on sale for 350 shekels. I’ve never seen a better deal on a pressure cooker. The store is right next to the Haaretz office.

  11. Stephen Paulger says

    You have misunderstood how electricity units work and as because of this the whole article is wrong. 560 Watt hours is over 8 hours, which means you have to divide 560 by 8 to get the hourly consumption, which comes to 70W (which you’ll notice is the rating of the device). 70W is significantly lower than your claimed power consumption of an oven.

    • Hi Stephen,
      I believe the post says the same thing that you are saying. It’s based on 8 hours at 70 watts (with the smaller slow cooker). If your slow cooker uses only 70 watts an hour it will usually be more efficient than an oven–it’s important to make the calculations according to your individual appliances and usage.

  12. Interesting. I can see how they are not energy efficient. Anything that runs for 8+ hours is probably going to use a good amount of energy. If only you could hoop one up to a solar panel…

  13. Ok… that’s a load of crap.
    Electric oven uses over 2kW and depending on the thermostat type it either turns off for a period of time and then turns back on etc.. or it decreases power to regulate temperature.
    so it’s not 2kW all the time …
    Slow cookers (at least this century made slow cookers) also have a thermostat so it doesnt use the max powerr even at the warmest setting all the time… it olso has similar mechnisms as the electric oven… you have to compare real world mesurements not misguided speculations about energy use.

    in oven:
    large amount of air and the large oven itself has to be heated and maintain teperature
    ovens don’t HAVE TO (but stil can) have good insulation because of bigger power surplus to compensate energy loss to the outside of the oven
    Higher temperature difference between the surroundings and oven make for greater energy loss
    high power short time

    in slow cookers:
    small amount of air an d small portion of the unnescessary things are heated up
    slow cookers use waaaay less power per unit of time than ovens and less than their maximum raiting
    they cook for longer so longer power consumption but on less wattage
    because their power is limited they tend to have better insulation
    because of the lower temperature difference the heat transfer to the outside is lower (the dependancy of heat transfer id not linear 100*C metal in contact with 0*C air in 1h will give away more energy than 10*c metal in 10 hours.
    so energy los per watt is smaller than in oven.

    But the real power use has to be measured because there are to many variables just to guess … and everyone cites a site that has the wrong assumptions.

    • Hi Al,
      Nice to meet you.
      The post takes into account that the oven turn off and on: “So while the heating elements use 1000-2000 watts an hour, most of the time they will be off and your usage is only about a quarter of that. A lot depends on your oven, its size, and how often you open it.”
      You wrote: “Slow cookers (at least this century made slow cookers) also have a thermostat” Not according to Hamilton Beach, a leading manufacturer: Q Are slow cookers hotter than the original ones from the 1970’s?
      A Yes. Slow cookers have changed over the years to meet food safety guidelines set by the UDSA. Slow cookers do not have thermostats, so they do not have temperature ratings for Lo and Hi settings. Lo simply uses less watts and takes longer to get to the same cooked temperature. This temperature will approach boiling.” Source:
      Agree that there are many factors that go into how much energy is required to cook food. Thanks for adding your thoughts.

  14. Al Green says

    Well my slow cooker (i dont know if i can pos model) has a thermostat (not only temperature switch i,ve replaced it once already) i’ve fixed two other slow cookers and one of them could have temperature switch but the other one also had a thermostat.
    and the thermostat is used continually (not only for controlling searing function or on of for heater element)

  15. Okay, Al, I will update the post.

    A slower cooker has a thermostat , so they can cycle on and off ,,
    so very energy efficient ,, for operation,, for the size ,,