More Monitors = More Cost To Electricity?

[anyboy9005]

Hello I've been using a laptop for a long time but I've been thinking of adding a second monitor, and wanted know how big could electricity bills go up by due to a second monitor?

 

[Scottray]

A standard 24 inch LCD monitor consumes maybe 20W. So let's say you using it 4 hours per day. Then we can approximate the electricity charge as:

20W * 4 hour/day * 30 days * $0.10 KWhours * 1KW/1000W = 20 * 4 * 30 * 0.10 / 1000 = $0.24 for a month

I used $0.10 KWhours as my electricity rate. Plug in your own rate. Overall, monitors are pretty low power devices. Not much additional electricity usage.

 

[Solandri]

If your electricity rates are the U.S. average of 11.5 cents/kWh, then each Watt a device uses turns out to be almost exactly $1 worth of electricity over a year if the device were left on 24/7. So a 20 Watt monitor left on 24/7 for a year would use about $20 worth of electricity (exact figure is $20.16).

From there you can divide by how often the monitor is on.

If you use the computer about 8 hours a day, that's 1/3 of a day. So you just divide $20/3 = $6.67 for the year.
If you use the computer only 2.5 hours a day, that's about 1/10 of a day. So $20/10 = $2 for the year.

If your electricity rates are higher or lower, you just multiply by the ratio. So if your electricity rates are 20 cents/kWh, then you just multiply by 20/11.5 = 1.74. And the $20 if left on 24/7 for a year turns into $34.80.