October 23, 2011

Does it Cost More to Use a Kettle or a Microwave?

I use an electric kettle to make tea.    Our kettle is an Aroma Kettle.  I'm not sure of the exact model but it is similar to the one pictured on the right.  I used to heat water in the microwave to make tea.   At some point I switched to using a kettle instead.   I can't even remember why I switched.  

I was curious to find out exactly how much power a kettle uses versus a microwave so I decided to test it.

The test

I boiled one cup of water with the electric kettle and I heated one cup in the microwave.   I measured the electricity used in both using my kill-a-watt meter.   It was a fairly simple test and the results are straight forward.  

First the Microwave:

I guessed that the microwave would use 0.0167 kWh.   Its a 1000 Watt microwave and if I run it for 1 minute then thats 1/60 of an hour.   Running a 1000 Watt device for 1/60 of an hour equates to 1/60 kWh or 0.0167.   I measured it to be sure..

I hope you can see that well enough.  Sorry the picture isn't that great but the lighting isn't good due to the kitchen cabinets overhanging the AC outlets.   The kill-a-watt meter shows 0.02 kWh consumption.   Thats close to the 0.0167 rounded up.

The electric kettle

I really had no idea how much power the kettle would use.

The kill-a-watt meter shows that it used 0.05 kWh.


The electric kettle uses approximately 2.5 times as much electricity to heat water as does our microwave.

Kettle = 0.05 kWh
Microwave = 0.02 kWh

Winner = Microwave

How much does this matter?

0.05 kWh is not a lot of electricity.   If I used the kettle to make a cup of tea every day of the year then that would equate to 0.05 kWh x 365 days x 11¢ per kWh = $2.01 electricity per year for the kettle.    THe microwave would use $0.80.    I'm spending about $1.20 more per year using the kettle than the microwave to heat my cup of tea.

[edit:  fixed references to 0.167 to properly read 0.0167]

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