how many candles do you need to heat a room

How many candles do you need to heat a room?

How many candles do you need to heat up a room? When it’s freezing cold, you have to be prepared. So, that’s actually a good question. Whether you’re doing survival, you spend a few nights in your off-grid cabin, or whether your room heater just broke. Heating with candles is definitely a thing that comes to your mind.

When my radiator stopped working, the question about heating with candles popped into my head. When I started my research, I was SHOCKED. There are dozens, if not hundreds of tutorials online about building a candle heater at home.

So, that’s what I tried to do myself. Together with a few calculations, I came to a conclusion.

Short version: To heat a room, you need 20 candles. According to research, the heating power of one candle is 80W. Therefore 20 candles are about the equivalent of one 1600W space heater. A candle heat source of 1600W combined is able to heat a room thoroughly. However, having 20 candles in your room is a fire hazard. Let’s cover the better alternatives.

How many watts does a candle have?

Luckily, I stumbled on a crazy science website with all kinds of different questions and answers. And that’s where I found the power rating of a single candle.

“The candle was burning 2 thousandths of a gram [of wax] each second which gives us a power of about 80 watts.”

thenakedscientist.com

To find that out, the researchers investigated petroleum-based candles. That’s the kind of wax most candles use. A candle burns about 8g of each and every out. Now, that would equal around 2.16mg of burned wax per second.

Chemists, of course, know exactly how much energy is stored in different molecules. You can simply look it up online. We know that candles consist of wax. They found that candle wax contains approximately 37 kilojoules of energy per gram.

Now, it’s easy to work out that a single candle produces 80W of power.

I’m sorry if that was too many numbers and facts for you. But anyway, now we know exactly how much power a candle has!

Does heating with candles make sense?

A single candle doesn’t change a lot. Placing three or four on your desk doesn’t do much as well.

To get the equivalent heat output of just one single space heater, you would need to light 20 candles. It sounds dangerous to me.

Now, depending on the size of your candles, they have limited burning time. Small tea candles burn for 3-4 hours, whereas standard-sized table candles last for 7-9 hours.

That means that your heating time is limited.

And after a few hours, your candles go out and you have to replace them. Ugh.

That doesn’t sound practical at all.

Here’s the recipe:

  1. Light 20 candles.
  2. Heat for 4 hours.
  3. Repeat

For heating a single room 24 hours, you would need 120 tea candles! And if you want to heat an entire home, or a cabin, let’s say with 3 rooms, you would need 360 candles!

Now think about how much that would cost you. And additionally, you have to constantly light and replace new candles.

In an absolute emergency, costs don’t matter. But you’ll just use up so many candles. It’s easier to just wear a few extra layers of clothes.

By the way, here’s a guide on the 21 cheapest ways to heat a room. And trust me, heating with candles is definitely not one of the cheapest ways (even if you initially think that it could be cheap).

Do flowerpot heaters increase the heat of a candle?

Heating with candles makes no sense. Or rather, it’s possible, but it’s totally impractical and cost-ineffective.

But still, there are hundreds of online tutorials about building a DIY candle heater that is both energy-efficient and doesn’t need many candles.

Here’s the basic setup.

candle flowerpot room heater

It basically works like this: Candles are placed below an elevated flowerpot. The heat of the candles goes up the hole of the flowerpot and creates suction at the bottom of the heater. This increases the burning rate of the candles a little because they constantly pull fresh oxygen from your room.

The flowerpot also acts as heat storage, similar to the metal body of an oil heater. It gets hot and even gives off the heat.

But it doesn’t work as well as you think. Here’s why:

You only get out what you put in. The candles that are placed below the flowerpot might produce slightly more heat because of the airflow. However, they also burn off faster. A candle can’t create “free heat”. So, you would have to refill it more often.

And in total, you would end up using as many candles as without the flowerpot method.

It’s just a fancy idea. The hot flowerpot gives the illusion that you create more heat than using plain candles. But that’s not the case.

Here’s a video that explains everything with more depth.

Candle vs. Space Heater: What’s better for room heating?

Now that we know that a candle doesn’t really make much sense, we can even go one step further and compare candles with space heaters. What’s better for heating and why?

1. Efficiency

A candle produces 80W of heat. Usually with an efficiency of around 90%. That means that 90% of the released energy is heat, whereas the rest is light. For heating, candles, therefore, have high efficiency.

From a theoretical standpoint, using a candle to heat is much better than an open fireplace, for example. With a fireplace, most of the heat goes up the chimney. Whereas with candles, the heat stays inside your room. Great!

But candles are not any better than regular space heaters. Regular space heaters have similar efficiency. Most of the electricity you put in is converted to heat.

In fact, in terms of efficiency, candles can keep up with space heaters.

2. Heating Capacity

Heating capacity is a term that describes the amount of heat that something can put out.

A candle can only produce very little heat. In fact, it produces a twentieth of what a space heater can produce.

The heating capacity of a candle is just enough to keep a tea hot. A space heater can keep a whole room toasty.

Of course, you can increase the heating capacity by just adding more candles. But that wouldn’t be a fair comparison.

A single space heater outputs as much heat as 20 candles, which makes it much more suitable for heating rooms.

3. Ease Of Use

When you want to heat a room with candles, you would have to have a large supply of them. You need to replace candles every few hours. Especially when you want to heat throughout the day, you’ll need to care for hundreds of candles simultaneously.

The worst thing is that there’s always something going wrong. If you, for example, open the door too harshly, the wind can blow out a few candles. You just constantly have to babysit them.

Compared to a regular space heater, candles are awful. You can just turn on a space heater and leave it on for hours. You don’t need to replace anything at all.

4. Safety

Candles are a fire hazard. I don’t think there’s anything I need to add to this point. Especially when you have kids and pets at home.

However, in an emergency, and when you have no alternative, you have to use them. I suggest to place them in spots, where kids can’t reach them. And to have a fan running on low to distribute the heat. Then, you are pretty safe. There will be no spots where the heat accumulates. And your kids can’t play around with them.

Space heaters are very safe. Most of the accidents that happen with space heaters are caused by misuse. For example, when you try to dry clothes on a space heater. Of course, it overheats and catches fire.

But as long as you use a space heater correctly, it’s absolutely safe. Especially nowadays, where they have all kinds of safety features like tip-over protection and automatic shut-off timers.

5. Power outage

Now, some people would say that in a power outage, candles are the last resort to keep your home warm. Yes, that’s right. But only if you’re not prepared.

There are space heaters that don’t need any electricity. Propane heaters use propane gas to produce heat. You can just hook up a propane bottle to your propane heater and it will heat for many many hours.

I suggest to always be prepared for the worst, and a propane heater is essential to keep warm in an emergency. Here’s my favorite propane heater (click to view my review).

It’s a model that I would trust even when the world ends. No joke.

Conclusion

You need 20 candles to heat a room. However, that doesn’t mean that using candles is a good idea. You will constantly have to refill candles because they burn off every few hours. To heat a room for 24 hours, you will need 120 tea candles. And on top of that, you will constantly need to take care of candles that go out because of the wind.

Heating with candles is not a practical idea. For emergencies, I’d rather recommend heating using a regular propane heater. It’s just way more effective. You don’t need to constantly change the propane bottle (it lasts for a long time!) and it’s cheaper than buying candles over and over again.

Read this next, so you can decide which type of heater is best for you: Infrared vs. Oil Heater (21 Pros and Cons)

About the Author

Daniel Hirsch

Daniel is an electrical engineer, blogger, and author. He studied electrical engineering and information technology and decided to blog about heaters after working in the temperature sensing industry.