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Kill A Watt Energy Monitor Review

Published on 23 January 2022

Kill A Watt is an electricity monitoring meter that tells how much electricity is being used by the device or appliance that is plugged into it. I have used mine for over a decade and it still works.

Kill A Watt is manufactured by P3 International and the one that I have is the basic version. It tells the following parameters -- current, wattage, Hz and kilowatt hour.

Kill A Watt Energy Monitor

Kill A Watt Energy Monitor


There are five buttons on the Kill A Watt meter. The first one is V for voltage, A for current, Watt for wattage, Hz for frequency and KWH for kilowatt per hour usage measurement. The LCD display is bright and shows no signs of old age, even though it is a decade old. The right-most button KWH shows the energy consumption by time used. The current rating is 15Amps. I have not tested this against heavy duty appliances such as the refrigerator, washer or dryer.

How this works

Plug in the Kill A Watt meter into a 120V outlet. By default, when this turns on, you see the Voltage setting on the LCD display monitor. In my case, the current voltage is 120. The monitor is large and bright, even after a decade.

Plug in any electrical device whose electricity consumption you want to measure and you will get the reading out. A few devices consume electricity even when not being used. Televisions, cable TV boxes and mobile device chargers almost always use up electricity when not in use.

Press the Watt button. I use this the most.

How much electricity does my MacBook charger use?

I want to know how much electricity my MacBook charger consumes. I plug in the MacBook charger into the outlet and press the W button. The reading continues to show 0. That's good, because I have seen a few older chargers consume up to 5W when idle (when the device is not plugged into the charger).

I then plug in the other end of the USB-C cable into my MacBook. The MacBook starts getting charged and the Kill A Watt's LCD display changes to almost 70W. The number is not constant because I have several programs running on my Mac. More programs would consume more energy, so there's a constant 65-70 watt usage on my MacBook when it is being charged.

Kill A Watt electricity usage by MacBook

Kill A Watt electricity used by my MacBook Pro 2020 model

Christmas string lights

I also measured each of my Christmas string lights and most of them take up the advertised wattage. The LED ones take up anywhere between 2W and 5W. The non-LED Christmas lights (incandescent) with the same length take up 40W to 50W.

Coming up

I will update this post with more energy readings from other devices in my house.

If you like this device or do not like this device, please let me know. Thank you for reading my post.

Created on 23 January 2022

TAGS: energy, meter

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