Check my math here but I think I have this right.


I have a 400 Watt HPS that I run 24 hours a day.

I get charged basically a dime per kilowatt hour from my electric company.

So we take 24 hours in a day times 30 days in a month.

So I run the light 720 hours a month.

Now the 400 watts becomes .4 kilowatts.

Multiply 720 times .4 and you get 288 which is the number of kilowatt hours my light uses.

Now multiply that times the cost of one kilowatt/hour of electricity and you get $28.80 per month.

I always figured mine cost double that. Good to know.