The power’s gone out. Your backup systems have failed, and the cold is setting in.
But you don’t plan on freezing to death. Instead, you’re going to improvise.
Luckily, you’ve got some old candles lying around. We know they generate warmth, but is it enough to heat a room? Well, that depends.
Candles have limited heating power. They’ll never be as functional as an electric or gas space heater, but you can maximize your chances of success in a cold-weather survival scenario if you know how to use them properly.
How Much Heat Can a Candle Produce?
To determine if a candle can heat a room, we need to examine its capacity for heat production.
We know that heat is measured in British Thermal Units or BTUs. On average, a candle will put out between 75 and 85 BTUs per hour. To heat one square foot of your home, you need about 34 BTUs per hour. That means, in theory, a candle should be able to warm 2 or 3 square feet of space.
Let’s say you’re in a room of 100 square feet. According to the math, you would need around 3,400 BTUs per hour to heat the space effectively.
That’s approximately 50 candles. Unless you’re summoning up a demon army, it’s unlikely you have that many candles lying around.
Is there a way to make a candle produce more heat? Absolutely not. You can add additional candles for more heat, but you cannot increase a single candle’s BTU power.
Learn the limitations of candle heaters before you put too much stock in this method.
What to Expect From Candle Heaters
Don’t expect a miracle. Candle heaters should be able to heat a small enclosed area and help you avoid freezing to death. However, they cannot become a comfortable heat source for you to use all winter long. Candles just don’t put out that much heat.
Candle heaters also work with varying degrees of efficiency in different situations. The general rule is that the colder a space is, the more time and energy it takes to heat it, and the less efficient your candle heater will be. Add poor-quality insulation and window drafts into the mix and they become even weaker.
There are a lot of wild claims about candle heaters. TikTok and YouTube are full of videos demonstrating their miraculous powers, but it’s important to remain objective.
There haven’t been any verifiable controlled experiments or published scientific articles on candle heater efficacy. With that in mind, they’re okay for emergencies—just don’t rely on them entirely.
Learn about one engineer’s experiments with candle heaters and what a real expert has deduced.
The Science Behind Candle Heaters
So, how exactly does a candle heater work? You’ve probably noticed that the air directly above a candle flame is much hotter than the air beside it. That’s because heat always rises, and cold air moves to take its place. So, your candle’s heat rises and disappears immediately as it burns.
As it reaches the ceiling barrier, heat radiates outward—you can’t even feel it up there, so it’s completely wasted. This is why space heaters work so much better than candles. They not only have more BTU power but all their power is blown directly in your face. In contrast, candle power drifts up and away.
But what if you could trap the heat closer to the ground? You’d definitely be able to feel warmer. A candle heater does just that. You place the candle heater over the flame, and it absorbs the heat. It essentially traps warmth from the candle’s flame, and that heat radiates out toward you.
Candle heaters are made from clay or terracotta pots. Clay is fireproof and has a high thermal mass, so it absorbs heat more effectively than other materials. The pot acts like a storage battery, releasing heat into the surrounding air over time. The pot will stay warm even after the candle goes out, increasing the time you get to spend not freezing.
Here’s a step-by-step process explaining exactly how a candle heater works:
- Light the candle, and it immediately begins to give off heat.
- Place the pot over the candle.
- Heat is transferred to the air inside the pot via convection.
- The warm air is absorbed into the pot’s thermal mass.
- The pot gives off warmth slowly via radiation.
Learn how heat transfers to understand how a candle heater can warm the air around it.
How to Make a Candle Heater
A candle heater is one of the best emergency heating devices because you can make it from everyday household items. You can also buy one, but that defeats the purpose. It’s good to know how to make a candle heater when you’re in a jam, and much better to save your cash and buy a more functional non electric heating device.
Here’s what you’ll need to make a basic candle heater:
- Clay pot (thermal mass)
- Generic short candles (heat source)
- Ceramic plate (base)
- Two bricks (allows airflow)
You can substitute these items with other non-flammable objects if you don’t have them. For example, you could use a muffin tin or cake pan instead of a ceramic plate as a base. And instead of setting the heater on bricks to allow airflow, you could use leftover tile.
You don’t even need any specific candles—you can substitute them for your own DIY candles and get a similar effect.
Here’s how to assemble a candle heater:
- Put your plate on the ground or table to act as a base. The dish will hold your candles and prevent them from setting the carpet ablaze.
- Arrange the bricks around the plate. The bricks will support the weight of the pot and allow airflow to reach your candles.
- Place your candles on the plate and light them up.
- Flip the pot upside down and set it on the bricks. If your clay pot has a bottom hole, cover it with another plate to prevent heat from escaping.
- Now, sit back and wait. As the candles burn, they will heat the pot. You should be able to get your hands toasty in a few minutes.
There are some variations of this method, but most won’t be any more functional. However, there might be some credence in using two nesting clay pots rather than one. You attach the pots with a bolt, nuts, and washers.
Theoretically, two pots will have a higher thermal mass than one alone and could retain heat for longer.
Check out this video and learn how to make a double-pot candle heater.
Tips for Using a Candle Heater
Not all spaces are suitable for heating with candles. Most are quite unideal, but there are a few ways to optimize your space for maximum heat retention and get the most out of your candle heater. What does that look like in practice?
Choose a Smaller Area
Heat has a bad habit of radiating away when you’re trying to get warm. The more room your heat has to wander, the more it dissipates and the colder you’ll feel. The smaller the space, the less heat dissipates and the warmer you’ll feel.
You can use this to your advantage by moving into the smallest space possible. Instead of sitting in your bedroom, sit in the bathroom or a closet.
Spread the Heat
You might already have a heat fan on your wood stove or fireplace. If that’s the case, take that sucker off and put it on your pot. It won’t work wonders, but it will help the heat blow toward you instead of radiating in all directions.
Learn how a heat-powered fan on your clay pot heater improves heat distribution.
Insulate Your Space
That troublesome heat is trying to escape again. Shut all the windows and doors in the room to block it.
It’s wise to gather up clothes, blankets, and towels at this point. Hang them over windows and around the room to add an extra insulation layer. You can even roll up a towel and place it beneath the crack in the door. Every step counts here, as even a few degrees can help you survive.
Stock Good Candles
One candle won’t necessarily put out any more BTUs than another. However, some candles burn for longer. The type of wax plays an important role here. Beeswax candles burn the longest, while soy comes in second place. Paraffin has the shortest burn time, but it is the cheapest.
Paraffin is refined from coal or petroleum and can produce soot. You don’t want to breathe in too much soot, so it may be better to go with beeswax.
Short multipacks like the Hyoola Beeswax Tea Candles are an affordable option. You can fit several beneath a clay pot for maximum warmth, plus they’ll give off a combined 48 hours of burn time.
Read more in our guide to the best candles for a power outage.
Watch Your Flame
Your candle flame can go out even if you have adequate oxygen flow. If this happens, you won’t immediately notice a change in the pot’s temperature because its thermal mass will continue to give off heat. To avoid lapses in warmth, check underneath your pot periodically to ensure all your candles are lit.
Add More Heat
When we’re cold, we tend to get lethargic. Don’t let that happen. Your body puts out more warmth than the candle, even at rest.
But body temperature increases significantly with exercise, and up to 80% of the energy you generate with movement is given off as heat. Don’t huddle around the candle silently. Get up, do some jumping jacks, and help the room get hotter.
Dangers of Using a Candle Heater
So, now you know how to make and use a candle heater.
But should you be using one? It depends on who you ask.
Your local survivalist club will probably love the idea, but the fire department will gasp in horror. The fire brigade in London went so far as to put out an official warning against using clay pot candle heaters, and for good reason.
Dozens of people had to be evacuated after a clay pot candle heater caught a UK apartment on fire in 2022. Meanwhile, hundreds of people worldwide lose their property and lives from candle-fueled fires yearly. There are quite a few dangers to consider, and you should weigh them carefully before lighting up your heater.
There may be a small risk of inhaling chemicals from paraffin wax. Some studies show paraffin gives off carcinogens like toluene when burned, but other studies have refuted this. Research in this area is conflicting, and we don’t really know the truth.
Since you’ll be in an enclosed space with little ventilation, any possible risks will be compounded. In light of this, simply burning beeswax or soy candles may be safer.
Research is not so conflicting regarding the dangers of a house fire. Remember, you’re working with an open flame. Any open flame can cause a fire, even if you cover it with a clay pot. To help mitigate the danger, you can move the clay pot toward the center of the room and away from any flammable materials. However, you’re still technically at risk.
The pot itself can get incredibly hot. The exact temperature will vary depending on the conditions around it, but people have reported being able to cook on top of their heaters. If it’s hot enough to fry an egg, it’s hot enough to fry your skin.
Putting a candle under a clay pot will also increase the temperature around the wax. This can cause it to melt more quickly than usual, and it can wind up all over the base. Melted wax could even spill out of the base and burn you. If it gets hot enough, the melted wax can ignite and cause a wax fire. Wax fires can lead to massive pools of burning wax and even fireballs.
Discover how candle wax can potentially cause fires and explosions.
Massive wax fireballs are only cool in the movies. In reality, they prove very dangerous. If you encounter fireballs, don’t put water on them. Water will only make the fire spread. Instead, treat this like an oil fire. Put it out by smothering it or spraying it with an extinguisher.
The clay pot itself can also be a hazard. If it contains any moisture, the water will expand exponentially as the pot heats up. The pot can crack, break, or even explode because of this expansion.
So, what’s the bottom line here? During a wintertime power outage, anything goes—including home heating with candle power.
But while a candle can help heat a room, you should consider it a last resort. It’s a dangerous method and doesn’t work that well. Your safety is critical, so weigh the threat of impending cold weather against the risk of candle heaters to make your decision.