How much is this costing me?
In this post I will teach you how to calculate your power consumption and figure out how much your devices are costing you. You will need a meter that can display either volts and amps or wattage. The most popular among miners seem to be the kill-o-watt meter, but since I'm working with USB powered SBC's, I'm using a USB power meter from ebay.
Figuring out wattage
If your meter can display wattage, then you can skip this step. For everyone else, you will need to get the volts and amps reading and put them into the following equation:
Amps * Volts = Watts
So If my Raspberry Pi 3 is using .86 amps at 5 volts, it's using 4.3 watts
.86 * 5 = 4.3
Figuring out costs
For the next step, you will need to know what the utility company is charging you per kilowatt hour. This information should be on your monthly bill. I'm charged $0.10 per kWh which is pretty standard in the United States. So, to figure out the total cost you will need this equation:
(watts / 1000) *operation hours *cost per kWh
For the Raspberry Pi example, I'm using 4.3 watts at $0.10 per kWh. I'll be running the Pi all month which is around 720 hours. Don't forget about the order of operations when doing the math (Parentheses, Exponents, Multiplication/Division, Addition/Subtraction)
(4.3 / 1000) * 720 * .10
0.3096
After rounding up, the Raspberry Pi is using $0.31 USD per month. If you're mining, you can use this information to determine if you're turning a profit. Hopefully this bit of information will help you pick the best coin for your mining endeavors. Good luck and happy mining.