Hi smk1970

it depends on whether you use the manufacturer’s quoted power consumption or you actually measure it yourself. You may find the two differ especially on cheaper light bulbs.

Using a 12 watt, a 60 watt light bulb and a TV quoted as taking 1 watt on standby as an example

multiply the wattage by the number of hours per day in use let’s call it 8 hours

lamp 12 watt x 8hrs = 96 watt hours

lamp 60watt x 8 hours = 480 watt hours (or Wh)

tv 1x 8 = 8 watt hours

then multiply that figure by the number of days in use, for example every day would be 365 days let’s assume 300 days

12W lamp 96x 300 = 28,800 Wh

60W lamp 480x 300= 144000 Wh

1W tv 8x300= 2400 Wh

divide Wh by 1000 to get kWh

multiply that by your KWh rate which is on your statement (don’t forget to add vat at 5% if the rate is quoted exc vat)

Lets day your rate is 15p a kWh inc vat

12W lamp will cost 28.8x15p=£4.32

60W lamp will cost 144x15p=£21.60

tv cost 2.4x15p=£0.36

Or to put it another way, every watt costs 8.76 x 15p (or your rate per kWh) if used for 24 hours 365 days

The examples used above are not meant to be an accurate guess as to what your actual devices use, I used a range to illustrate. My old tv used over 2W in standby, the newer one less, but I don't leave anything in standby apart from essentials like routers. It's not practical to switch certain things off as much as I'd like to....

it depends on whether you use the manufacturer’s quoted power consumption or you actually measure it yourself. You may find the two differ especially on cheaper light bulbs.

Using a 12 watt, a 60 watt light bulb and a TV quoted as taking 1 watt on standby as an example

multiply the wattage by the number of hours per day in use let’s call it 8 hours

lamp 12 watt x 8hrs = 96 watt hours

lamp 60watt x 8 hours = 480 watt hours (or Wh)

tv 1x 8 = 8 watt hours

then multiply that figure by the number of days in use, for example every day would be 365 days let’s assume 300 days

12W lamp 96x 300 = 28,800 Wh

60W lamp 480x 300= 144000 Wh

1W tv 8x300= 2400 Wh

divide Wh by 1000 to get kWh

multiply that by your KWh rate which is on your statement (don’t forget to add vat at 5% if the rate is quoted exc vat)

Lets day your rate is 15p a kWh inc vat

12W lamp will cost 28.8x15p=£4.32

60W lamp will cost 144x15p=£21.60

tv cost 2.4x15p=£0.36

Or to put it another way, every watt costs 8.76 x 15p (or your rate per kWh) if used for 24 hours 365 days

The examples used above are not meant to be an accurate guess as to what your actual devices use, I used a range to illustrate. My old tv used over 2W in standby, the newer one less, but I don't leave anything in standby apart from essentials like routers. It's not practical to switch certain things off as much as I'd like to....