How much is it costing me to run my lights per hour or per month

cannafan;1944445 said:

I've made a formula here for determining electric use per hour with lighting.
I know that you can calculate kilowatt-hour from watts and hours. You can't convert watt to kilowatt-hour unit since watt and kilowatt-hour unit represent different quantities

Here's what I have:

HOW MUCH DOES IT COST ME PER HOUR OR PER MONTH TO RUN MY LIGHTS?

So, let’s do this for a 400W hps light on 12/12 light schedule:

To convert watts to kwh hour do the following:

kilowatt-hour = watt × hour / 1000
400w x 12 hours divided by 1000 = 4.8 kwh

Now determine the cost per hour of 4.8kwh (or 0.480)

kilowatts X unit cost (your local cost per kwh) = cost per hour
My local unit cost is approx. .153 per kwh:

0.480 x 0.153 = 0.07344 per kwh
.07 cents per kwh x 12 hours = .84 cents per 12 hour cycle
.84 x 30 days = $25.20 per month to run a 400W hps light

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