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How Many Watts? Power Consumption Explained

Curious about the cost of powering your PVR, set-top box, Home Hub and other household equipment?

We covered watts and power consumption in Show 30. We'd encourage you to take a listen to the MP3 of the show.

As promised in the show, here's a handy table of costs, plus some tips on how to bring down your electricity bills.


Listen to our audio feature covering Watts, Power Consumption and Energy:

Play Show button Download show now button


Cost of running appliances and gadgets

Interested in finding out how much power your home technology and appliances are costing you a year? We've used a standard power meter to identify the cost of running your gadgets and equipment.

Household appliances

Product Notes Watts Cost per hour Daily usage (hours) Estimated cost a year
60 watt lightbulb Standard bulb 60 £0.007 5 £11.89
Energy-saving bulb (Philips) Equivalent to a standard 60 w bulb 11 £0.001 5 £2.18
Kettle Average kettle 1800 watts 1800 £0.195 0.25 £17.83
Washing Machine Average cycle (2000w heat, 500w spin, 250  wash) 700 £0.076 2 £55.48
Fridge Average fridge consumes 35 watts 35 £0.004 24 £33.29


This page was actually put together as a result of a stack of requests to find out how much power the BT Home Hub uses, and how much it costs to run this router each year. Here are some numbers for the Home Hub and other computing gadgets.

Product Notes Watts Cost per hour Daily usage (hours) Estimated cost a year
LCD Monitor 17" Sony 75 £0.008 8 £23.78
Desktop PC Average 60w idle, 120 loaded 90 £0.010 8 £28.53
Router - BT Home Hub v1.0 / 1.5 wi-fi enabled 8 £0.001 24 £7.61
Router - BT Home Hub v2.0 10 watts (7 watts powersave) 10 £0.001 24 £9.51
Homeplug Powerline adapter D-link Ethernet Devolo Hs85 3 £0.000 24 £2.85
Printer (idle) Estimated 3w 3 £0.000 24 £2.85


TV and Video

Product Notes Watts Cost per hour Daily usage (hours) Estimated cost a year
TV - LCD (Sony Bravia KDL32S3000) When on 115 £0.012 4 £18.23
On standby 0.6 £0.000 20 £0.48
PVR (Humax PVR9200TB) When on 20 £0.002 4 £3.17
On standby 6 £0.001 20 £4.76
Sky+ (Thomson 160) When on 24 £0.003 4 £3.80
On standby 12.2 £0.001 20 £9.67
BT Vision Box When on 22 £0.002 4 £3.49
On standby 21 £0.002 20 £16.64
Top Up TV Anytime (Thomson DTI-6300) When on 18.2 £0.002 4 £2.88
On standby 17.3 £0.002 20 £13.71
DVD Recorder (SONY RDRGX120) When on 17 £0.002 4 £2.69
On standby 3.5 £0.000 20 £2.77


Other Equipment

Product Notes Watts Cost per hour Daily usage (hours) Estimated cost a year
Nokia mobile charger Nokia 6033, screen on 4 £0.000 24 £3.80
iPhone 3G charger Charging with screen off 2 £0.000 24 £1.90


How these results are calculated:

We've calculated these prices based on the rates of a standard UK Electricity provider. Here's what we've used:

Provider: Scottish Power (Tariff: Fixed Price, London)
Rate: 10.857 pence per kilowatt-hour
Rate last checked: 1st August 2011


How to calculate the cost of equipment usage:

It's easiest to take the example of the good old 60 watt electric lightbulb.

How many watts? 60. The watt is a measurement of power - so you can say 60 watts of power are required to make this lightbulb light up.

The measurement of watts is only meaningful when calculating cost, if you use watt-hours (how much to light the bulb for an hour).

Your electricity provider will bill you by the kilowatt-hour (kWh), and that's what your electricity meter records.

A 60 watt lightbulb left switched on for one hour is equal to 0.06 kWh (divide 60 watts by 1000 to get the kW) - so you multiply 0.06 kWh by your provider's kWh price, to get the cost.

E.g: 60 watt bulb for one hour = 0.06 kWh , multiply by a rate of £0.10 per kWh... is £0.006


Listen to our audio feature covering Watts, Power Consumption and Energy:

Play Show button Download show now button


Recommended Products:

Want to keep an eye on your kilowatt-hours? We recommend the following meters:

Efergy BoxEfergy Energy Saving Meter

This records your home's electricity consumption and converts it into a monetary value, based on the cost price of your electricity. This is recorded by day, week and month, and updates every six seconds, so you can easily see the cost of turning on the TV or making a cup of tea. A great product, which we covered in Show 19.

The Efergy energy-saving meter is available from Maplin and Ethical Superstore

See our review of the Efergy meter

Energy Meter SocketPlug-in Energy Monitor

Plug this into a spare electrical socket, and you can test how much juice a piece of equipment is eating. Typically, these measure voltage, amps, watts , volt-amps, hertz and power factor.

Pictured here is the plug-In Mains Power and Energy Monitor from Maplin Electronics


Your questions answered

Q. Does a shaver socket use power when there's nothing plugged in?

If you have a shaver socket that uses an isolation transformer (most do), and it doesn't have an on-off switch (most don't), then yes, the shaver socket will use a minimal amount of power (we estimate 1 or 2 watts) when there's nothing plugged in.


Q. How much does it cost to recharge batteries?

After a question from a listener in Show 60 - We finally solved the "are rechargeable batteries cheaper?" question. See our Rechargeable vs Normal Batteries maths


Got a comment or question? Please post in our Technical Discussion forum


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Got a question about power consumption that we can answer in our next podcast?
Call 020 8133 4567 or send us a message

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