Thermal Cooker vs Slow Cooker: Which is Better?

As a single Dad who has 3 kids and runs his own business making a healthy, tasty and nutritious dinner can be difficult. Slow cookers and thermal cookers allow you to prep dinner in the morning and have it cooked and ready when the kids get home from school.

While thermal cookers and slow cookers are similar in that they cook food at a low heat over a long period of time, but they work in different ways and there are pros and cons to each.

Thermal cookers and slow cookers both work by slowly cooking food and keeping it hot over a long period of time. Thermal cookers you use a stove to heat food to boil and then the insulated container


I wanted to do the research to see which type of cooker I should buy.

TL;DR Summary


How They Work

Thermal Cooker

  • Unpowered and portable
  • Insulated to keep food hot all day. Food slowly cools down over time
  • Pre-heat food to boiling temperature first

Slow Cooker

  • Powered – must be plugged in
  • Uses heating element to keep food at constant temperature
  • Food can be put in cold/raw

Both thermal cookers and slow cookers cook food over a long period of time, but how they do it is different.

A slow cooker is connected to power and uses a heating element inside the device to cook the food at a constant temperature – usually around 79–93°C (174–199°F).

A slow cooker needs to be constantly connected to power in order to cook food and to keep it warm. If it loses power the food will stop cooking and may spoil before you get to eat it.

A thermal cooker on the other hand doesn't use any power but is rather just keeps the food hot by using vacuum insulation similar to how a Hydro Flask bottle works.

You first heat up the food on the stove, usually to boiling point, then place the food inside the thermal cooker which uses it's vacuum insulation to keep the food hot.

The heat of the food then cooks it slowly over time.

According to A Heart Full of Joy their thermal cooker kept the contents of their food above 160ºF (71ºC) for 8.5 hours and kept it above 140ºF (60ºC) for up to 15 hours!


Thermal Cooker

Around $70-$200 (most around $160-$180)

Slow Cooker

Range from $20-$150 (lots of affordable options)

When it comes to price there is a HUGE different between the thermal cooker and the slow cooker.

I actually expected the thermal cooker to be cheaper because it doesn't have any electrics or moving parts but it turns out slow cookers are way cheaper than thermal cookers.

Thermal cookers started at around $68-$70 but most of the options out there are around $150-$180. This isn't cheap and if you're on a budget this may be too expensive for you.

Slow cookers on the other hand were much affordable. The cheapest slow cooler I saw was this super affordable one on Amazon and it was less than $15 at the time of writing. There were also a lot of different options under the $30 mark, including the popular brand “Crock pot” which you can see on Amazon here.

Not all slow cookers are cheap and higher quality slow cookers with more features cost a lot more and are similar in price to a thermal cooker. But generally speaking most people can get a good enough slow cookers for $20-$50 but will need to spend around $150-$180 to get a good thermal cooker.

Energy Usage and Cost To Run

My next thought was maybe slow cookers are expensive to run and a thermal cooker would save you a lot on electricity.

So while thermal cookers cost more upfront maybe they save you money over time the more you use them. Because they don't require power to run they must save you in electricity costs right? Wrong!

I looked into how much electricity a slow cooker uses and it turns out it isn't much at all. They generally only draw between 75-210 Watts of power depending on whether they are on low, medium or high.

Over the course of 6-10 hours they will only use roughly 450-2,100 Wh. Depending on how much you pay for electricity this means to cook an entire meal in a slow cooker from 6-10 hours will only cost between 4-65 cents. Not even $1.00.

But what about thermal cookers? Don't they use no power to run at all?

While thermal cookers themselves don't draw power you do first need to heat your food up to boiling temperature before putting it in your thermal cooker.

Given that stoves usually use around 2,000 Watts of power to cook your food. If it takes you 30-60 minutes to cook your food and bring it to boil you're looking at 1,000-2,000 Wh of power.

This is basically identical power usage to a slow cooker. But the power is just used all at once to heat the food up whereas the slow cooker uses the power over the course of the day.

So a thermal cooker doesn't seem to save any money when it comes to how much electricity you use.

So Why Buy a Thermal Cooker vs a Slow Cooker?

Given that slow cookers are significantly cheaper than thermal cookers and they have similar energy usage what is the benefit of buying a thermal cooker over a slow cooker?

Why bother?

Doesn't Use Power, So You Can Feel Comfortable Leaving It All Day

For a lot of people leaving something with a heating element going all day when you're not home sounds dangerous.

While slow cookers are considered safe to leave on all day without a fear of fire I can understand these concerns.

I live in an older style house and lets just say the electrical wiring isn't the best. Leaving on a slow cooker all day in my house would stress me out.

However, because a thermal cooker doesn't use any power at all I don't have to stress about the potential for fires in the device itself or in the walls of my house (due to bad electrical wiring).

Also, because it is so well insulated the outside of the thermal cooker doesn't even get hot to touch. So I can leave it on any surface or bench and not have to worry about it.

It's Portable, You Can Take It Anywhere

Another benefit of the fact that thermal cookers don't need to be plugged in is that you can take them anywhere with you.

You could take it to work with you to eat for lunch, or dinner if you're having a late night. You can take it on a picnic with you or I could even prep it in the morning at home and take it with me in my off-grid campervan and have a nice cooked meal ready to go at dinnertime.

Truthfully, this idea of taking it away with me in my campervan is one of the main reasons I'm considering a thermal cooker over a slow cooker.

You Can Cook Using Gas, Perfect for Off-Grid or Camping

Slow cookers require constant electricity in order to work. However, thermal cookers just require you to heat up your food in the inner pot first.

This can be done using either a gas or electric stove. So if you're off grid and don't use a lot of electricity or you have a gas stove then this is a perfect option.

Again coming back to my campervan. I've got a gas stove which means I can prep dinner in the morning and heat it up then put it in my thermal cooker and leave it all day and it'll be ready for either lunch of dinner time.

It Can Be Used To Store Cold Things, Including Ice Cream

While thermal cookers are primarily used to keep food hot and cook food slowly the vacuum insulation can also be used to keep things cold for a really long period of time.

You can make ice cream, store it in the freezer in the inner pot and put it in the insulated outer pot and take it with you. It's actually one of the best ways to keep ice cream frozen.

The ice cream will stay frozen all day and will still be cold to eat a night time after dinner.

You can also use thermal cookers to keep ice frozen for days at a time. Below you can see a video where I was able to keep ice in a Hydro Flask (which uses the same insulation) for OVER 3 DAYS!

Given a thermal cooker is even bigger I estimate it could keep ice even longer and would outperform most coolers.

They Can Be Used To Transport Hot Food On The Go

Thermal cookers are actually one of the best ways to keep food hot on the go.

Because they use vacuum insulation they are great at keeping food hot for a long period of time.

You don't have to cook food in them but you can preload them with already cooked food and it will keep it hot for a couple of hours (or even longer).

So you can use a thermal cooker to transport food to a friends house, take it to a backyard bbq or a picnic and still have hot food to eat when you're ready.

It can also be great for keeping food hot at a party. It's a pretty versatile piece of cooking equipment.

Best Thermal Cookers

Why Buy a Slow Cooker vs Thermal Cooker

A thermal cooker has a lot of benefits over a slow cooker. It's more portable, can also be used to keep things cold and it doesn't use any power to run.

So why bother buying a slow cooker over a thermal cooker? What are the benefits and who is a slow cooker better for?

Much More Affordable

One of the major benefits of a slow cooker over a thermal cooker are just how affordable they are.

If you're on a budget you may not be able to afford to splurge on a thermal cooker costing upwards of $150. But there are so many slow cooker options that only cost $20-$30, which is much better for people on a budget.

Given they don't actually use much energy they remain a fairly cost effective way to cook meals.

Easier To Use

Because slow cookers have an active heating element prepping and cooking meals can be easier than a thermal cooker.

For a lot of recipes you just throw in the ingredients, spices and liquid/water and then shut the lid and turn the slow cooker on.

With thermal cookers you need to bring the food to boil on the stove first, sometimes leaving for 30+ minutes before transferring into the thermal cooker.

If you're in a rush you might not have time for this.

But a slow cooker you can just throw everything in and turn it on. It makes it quicker and easier to cook meals.

More Recipe Options

Because slow cookers have an active heating element there are more types of meals you can cook in a slow cooker compared to a thermal cooker.

Many of them come with racks so you can put in a chicken or roast and slow cook it over the course of a day. This isn't something that's possible with a thermal cooker as it requires the food to be extremely hot when you load it up.

Cook Smaller Quantities Of Food

Slow cookers can effectively cook smaller meals all day long without issue.

However, thermal cookers rely on the thermal energy already in the food to keep it hot. If you have a smaller meal there is less energy and food can cool down too quickly.

For small meals you really need a small thermal cooker, which is an extra expense. But with a slow cooker you can easily cook small meals just like you can cook large meals. The size of the meal isn't an issue.

This is more convenient for single people or couples who only want to make smaller meals.

Keep Food Warm Above 140ºF (60ºC) For Long Periods of Time

Under 140ºF (60ºC) is considered the “danger zone” where bacteria can easily grow.

Because a slow cooker has an active heating element many models will work to keep your food warm for an extended period of time, even up to 24+ hours.

While a thermal cooker can keep food hot for 8+ hours and even keep it above 140ºF (60ºC) for up to 15 hours the food will cool down slowly over time and sometimes it can enter the danger zone too early and your meal can spoil.

You don't have to worry about this with a slow cooker as it'll use electricity and it's heating element to keep the food hot all day long, until you turn it off.

The Best Slow Cookers

Thermal Cooker vs Slow Cooker: Which Is Better?

So when it comes to thermal cookers vs slow cookers which one is actually better and which one should you buy?

Well neither is objectively “better” than the other but each of them have pros and cons.

A thermal cooker is great for people who want to take their food on the go, like to cook with gas or don't want to leave a heating element running all day long when they aren't at home. They can also be used to keep things cold, so they are versatile.

Slow cookers are great for people who are on a budget and who are making most of their meals at home and don't need to take them on the go. Slow cookers also make food prep easier so are better for people who are extremely time limited.

It's up to you to decide whether the portability and flexibility of a thermal cooker outweighs the cost savings and ease of use that a slow cooker gives you.

Both thermal cookers and slow cookers work great and can be an amazing addition to your kitchen. Choose which one best suits you and I hope you enjoy it.