What is cheaper: Boiling water

What is cheaper: Boiling water in a kettle or a microwave?

Do you generally use a microwave or a kettle to boil water? Is boiling water in a microwave cheaper than boiling water in a kettle?

What is cheaper: Boiling water

Many people believe it is cheaper to boil water using a microwaves as it is faster. Are microwaves really more cost-effective? Is boiling water in a microwave cheaper than boiling water in a kettle?


Kettles are designed specifically for heating water, making them more efficient for this purpose. Microwaves, on the other hand, heat everything in the appliance, including the air and container, which wastes energy.

According to Tom Williams, a researcher at the National Renewable Energy Lab, kettles are 80% more efficient than microwaves. There are two main reasons for this. Firstly, most electric kettles are properly insulated. Secondly, the heating coil sits directly in the water, meaning less heat is lost to the air. While heating water in a microwave, heat escapes during the process.

Losing water while it warms up is common in a microwave. A microwaves causes the water liquid to superheat and reduces it to vapour. This leaves you with less water in the end.


While time is not a factor impacting your wallet, it is often the reason for choosing to heat water in a microwave instead of waiting for a kettle to boil the water.

Using a 3kW kettle to boil just enough water to fill one average-sized cup, will take around one minute. In comparison, heating one cup of water in a low kilowatt microwave (0.6kW) will take around two minutes, according to an article published in the Mirror.

The verdict

According to estimations by the Centre for Sustainable Energy, you can boil one cup of water within two minutes using a microwave. An electric kettle only needs around 100 seconds to reach boiling point. They found that it is cheaper to use a microwave for larger quantities of water. You will save money, however, if you use a kettle for a smaller amount for example enough for one cup of coffee or tea.

In an article published by The Guardian, testers used one litre of water to determine whether it is cheaper to boil water in a microwave or to use a kettle. The verdict was that it takes the same amount of energy to heat one litre of water no matter which method of heating you use.

Because there are other factors that will influence the electricity usage, for example the wattage of your microwave, it is worthwhile doing your own test and using the information provided here as a guideline.