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What does it do

A Kill-A-Watt meter monitors whatever is plugged into it for how much power being drawn by the device connected. If you suspect an appliance is using more power than it should be, you can monitor it for a few days or even a month and see exactly how many kwh are being drawn. Using your latest electric bill you can calculate the cost per kwh and determine how much the device costs on a monthly basis to run.

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This is really useful for optimizing crypto mining rigs to find a good balance of performance and power usage.

How much does it cost?

They used to cost around $30 but have dropped considerably over the last few years. You can currently get one for under $20.

Does it work?

I have two of them I have used for a many years and while I cannot be 100% sure, I feel very confident they are accurate. Monitoring Ethereum mining rigs provided a very good test on it's accuracy and backed up the numbers I received from the device.

There is a newer version of the device

The newer version of the device is pretty much the same thing does the calculations on the device for you. I wouldn't spend the extra $7+ as it only takes 2 seconds to calculate the cost based on your kwh rate and what the device reports but it is available if you are interested.

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Internet Enabled Kill-A-Watt Meter

Some users have modified their Kill-A-Watt meter with an arduino board to enable Internet reporting. Not something I would do, but very interesting.

Where can I get one?

I haven't seen these sold locally but Amazon sells them for less than $20.

Review: 9/10

I really love the device, it works really well and appears to be very accurate. It would be nice to have remote Internet reporting built in, but there are more expensive version of the product that does this. For less than $20 it can save you a lot of money. Highly recommended.