Kettle Boiling Costs: Free Calculator + Data

A kettle in the middle of a kitchen

Are you in love with hot beverages but are worried about the cost of boiling water in your kettle?

You’re not alone! In fact, this is a very common concern among tea lovers and other people that prefer using this method over microwaves or regular pots.

Kettles are nothing new, and while they have become more technological with the passing of time, they’re still designed to fulfill a single purpose – heat up water to a boiling point. However, while their user hasn’t changed much, the cost of utilities has, and for the worse, unfortunately.

Whether you’re using a traditional kettle that needs fire, or an electric version, lowering the resources needed to reach the perfect temperature is key.

This is why, I’ve created the article below, where you’ll find a free calculator to estimate how much power you’re using in the process. I’ve also included some insightful data you’re going to love.

Keep reading to get all the answers!

The Calculator

How I’ve Estimated Kettle Boiling Costs

In order to create this calculator, I took into account several factors, such as the cost of electricity (as you know, this varies from State to State), and the amount of water you’re boiling (4 cups = 1L). I also considered the power of your kettle, which might not make sense right now, but please bear with me and it will.

By taking all these elements into account, we can reach an approximate power consumption for this appliance, so you can keep it in check and even try to work out ways to reduce it further.

How Long It Takes to Boil Your Kettle

For my fellow kettle nerds out there, let me walk you through the exact calculations I used in the tool above. If you’re as curious as me, you’ll love this detailed explanation, but if you’re not, you may want to skip this part altogether and move to the next section instead!

A kettle on a kitchen countertop
Boiling times differ depending on the kettle, but the cost might be a little more constant

Working Out the Energy Needed

If you still have your old physics book from school lying around somewhere, it’s time to go back to the basics. The first thing you need to remember is the heat capacity of water. In Joules, this can be defined as the energy required to increase the temperature of water by 1 degree Celsius.

For this particular liquid, that number is 4.2kJ/­oCkg.

After calculating this, we’ll have to know the starting temperature of the water we’re trying to boil. Under normal circumstances, room temperature should be about 20 degrees Celsius (68 °F).

Once we have this data, we need to factor in the target temperature, which, in the case of water, is 100 degrees Celsius for the boiling point.

Now that we have all the information we need, let’s crunch some numbers. To calculate how much energy is needed to make 1 cup of water reach its boiling point we must multiply (heat capacity * temperature change *volume of water).

In this case, that would be (4.2kJ/­oCkg * 80 °C * 0.25L), which results in 84kJ (kilojoules).

Working Out Time Taken

Now that we know exactly how much energy is needed to make 1 cup of water (or 0.25L) reach its boiling point of 100 °C, we can use the equation Time = Energy / Power. This will help us work out how long it will take your kettle to boil. In this particular instance, power will be measured in kW (kilowatts).

A person holding a timer in a red background
The more powerful a kettle is, the quicker it will make water boil

Since we already calculated that a cup of water needs 84 kilojoules to reach its boiling point, then we can do some simple equations. For this example, let’s consider a kettle with a power of 2000 watts, or 2 kW:

Time = Energy / Power


Time = 84kJ / 2 kW

Time= 42

By these calculations, we can conclude that when placed to boil in a kettle with 2 kW (or 2000 watts) of power, it will take roughly 42 seconds for a cup of water (0.25L) to reach its boiling point of 100 °C.

*These results may vary slightly depending on the starting temperature of the water and the wattage of your kettle, as any changes in either factor will affect the entire equation.

Why Power Doesn’t Matter

If you’ve been messing with the calculator above for a while now, you’ve probably noticed that the cost of running a really powerful kettle and one that isn’t so much so is the same. And believe it or not, this isn’t an error!

In fact, it all comes down to the time-power tradeoff.

You see, a kettle that has 2000 watts of power and takes 42 seconds to boil your water will consume as much electricity as a 200-watt model that takes 7 minutes. In theoretical terms, this means that time and power cancel each other out, which means that you’ll end up paying exactly the same amount of money for any model.

 Cost to Boil a Kettle

As I said earlier, this remains virtually the same regardless of the kettle model. The only difference in that regard will be with time, as a more powerful kettle will make water reach its boiling point considerably faster than one with lower wattage.

So, if you’re a little impatient, you might be better off buying a high-wattage appliance. Just make sure that you’re plugging the kettle into an outlet that can take the high amount of power required, as otherwise, you might end up blowing a fuse.


That about sums it up!

If you’re someone who loves drinking tea or any other kind of hot beverage, owning an electric kettle is a must. But what happens when you suspect it might be skyrocketing your electricity bills? Then, you might have to think twice about using it so often.

Luckily, as I hope this piece has helped you better understand, the wattage and model of the kettle you own will not change the cost of boiling water. The main difference will lie in how long you’ll have to wait to get the desired results.

Thank you very much for sticking with me all the way to the end. If this article proved useful and answered your most burning questions, please make sure to check out our other incredible resources below and consider subscribing to our newsletter.

I wish you nothing but the best!

— Craig.

Hi there! I’m Craig, and I’m the founder of Appliance Analysts. When it comes to appliances and anything electrical, I’ve always loved opening things up, figuring out how they work, and fixing them. This website is where I share free advice from myself and our experts to help our readers solve their appliance/HVAC problems and save money. Read more