Calculating kilowatt usage

ey143

I'm trying to better understand how kilowatt usage is measured. If I have a 2 kW electric fan heater that is being used on full power setting how do I calculate how much it costs per kilowatt. I mean, if I leave the fan heater on for one hour does that mean it only cost me approximately 16p as per typical per kilowatt usage charges are this much at present?

Equally if I leave only a 25 what energy-saving light bulb on how do I know actually how much it consumes in terms of cost?

DevCoder

wattage x hours used ÷ 1000 x price per kWh = cost of electricity

DevCoder

So a 2 kw heater for 3 hours would be

2000 x 3 ÷ 1000 = 6kw/h

6 x 16p = 96p for a 2kw heater for 3 hours at 16p per kWh

ey143

Sorry I asked a completely incorrect question without giving too much thought. What I meant to ask was when any item states consumption of electricity is that consumption based on an hourly basis? So does a 3kw heater take 1h to consume 3kw even though its pulling it continuously?

Hope my question makes sense.

I_have_spoken

Watt is a unit of power, measuring the rate of energy conversion.

The kilowatt hour is a unit of energy; if the energy is being transmitted or converted at a constant rate over a period of time, the total energy in kilowatt-hours is the product of the power in kilowatts and the time in hours.

So a 3kW electric fire will consume 3kWh of energy after 1 hour

closed

if you use a 3kw kettle for an hour it uses 3kwh, if you use it for 30 minutes, it uses 1.5kwh, if you use it for 20 minutes it uses 1kwh.

The electricity bill is charged in kwh , not in kw

heaters and kettles obviously have thermostats which turn them off when upto temp, so electricity is only used when they are actively heating

a 25watt bulb would run for 40 hours on 1kwh of electricity (1000/25)

if you are paying 16p/kwh, you should shop around, and led bulbs are more efficient then cfl.

ey143

This is exactly what I thought however I couldn't understand when during the winter I was in my new freezing home and used a 2kw heater it seemed to use more than 2kw in the hour (everything else in the house was off).

Norman_Castle

ey143 wrote: »

Sorry I asked a completely incorrect question without giving too much thought. What I meant to ask was when any item states consumption of electricity is that consumption based on an hourly basis? So does a 3kw heater take 1h to consume 3kw even though its pulling it continuously?

Hope my question makes sense.

Power consumption marking are maximums given to prevent overloading. Heaters without thermostats and light bulbs tend to run at the stated maximums. Many items use much less.
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