# Calculating power consumption

Hmm.. not sure whether I posted this in the right place, but I would like to ask. How do you calculate the power consumption for electrical appliances. Please try to explain as simple as possible, cause I am not that good with the terms used =X

 KISS Posts: 12,620, Reputation: 4388 Uber Member #2 Mar 31, 2009, 09:56 AM

Lets do some simple things like toasters and light bulbs. Let's leave out motors, so refrigerators are not covered.

Power is typically measured in watt-hours or killowatt*hours.
A killowatt is 1000 Watts.

Say you have a 100 W light bulm on for 10 hours per day and you'd like to know how many killowatt-hours per month.

100 W is equal to 0.01 KW; 100/1000

0.01 KW * 10 hrs = 1 KWH

Note that KW * h = KWH
and 0.01 * 10 = 0.1
so you have 0.1 kWH/day

If you wanted to know how much electricity you used in a month you would multiply the result by 30 days converted to hours.

so 0.1 kWH/day * 30 Days/month * Day/24 hrs

The hrs cancel. The days cancel. So you get

0.1 * 30 / 24 KWH/month ot X KWH/month
To find out how much this cost, you would multiply by your electric rate, say 10 cents/KWH

(0.1*30/24)/0.10/KWH

When you check the units it will be in currency.

I hope I did this right?
 hokiluki Posts: 38, Reputation: 1 Junior Member #3 Apr 1, 2009, 08:06 AM
Wow. Thanks a lot. That's exactly what I wanted.
What does this "/" mean by the way o.o
 ohb0b Posts: 215, Reputation: 65 Full Member #4 Apr 13, 2009, 02:28 AM

"/" means divided by.

100/4 means 100 divided by 4.
 KISS Posts: 12,620, Reputation: 4388 Uber Member #5 Apr 13, 2009, 02:46 PM

10 cents / KWH means 10 cents per Killo-Watt hour

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