How much power does your computer use
article compiled by steve

Have you ever wanted to know the actual power consumption
of your computer equipment ??

Many people may wonder how much it costs to run their computer equipment, especially when the electricity bill hits the doormat or email Inbox.

There are many opinions, figures and statistics ‘out there, in cyberspace’ ….. but take care.

Don’t base your figures on the manufacturers or retailers technical specifications.

These can be misleading if they use calculations based upon the power supply output or potential output.

A quick and VERY CLEAR way to measure power consumption is with a Plug in Electricity Consumption Meter

The following description describes an excellent meter that I purchased to test how much our computer equipment was consuming.

Plug-In Electricity Consumption Monitor

Plug-In Electricity Consumption Monitor Ideal to find the electricity consumption and running costs of:

– Fridges and Freezers

– Computers and all associated peripherals

– Standby Costs of TV, DVD, computer, stereo, video, chargers etc

– Washing Machines – Find the cost of your 30, 40, 60 degree wash

– Dehumidifiers & Air Con units

– Pond pumps, Swimming pool pumps (if they have a plug)

– Televisions – CRT, LCD or Plasma

– Anything that plugs into a wall socket !


Simply plug this monitor into the wall then plug the item into the monitor and you’ll see exactly how much electricity it consumes.



Once you have this figure it’s easy to work out the running cost.

Be prepared for some surprises!





All the functions and how to use the monitor are described in detail below

What will this monitor tell you and how do you use it ?

















Take a closer look at the display

Mode 1 – Volts

Simply push the ‘Volt’ button to see the voltage of the supply.

In the average house it will show around 240v, if you have 3 phase it’ll show around 230v.

Mode 2 – Amps

Push the ‘Amp’ button to see the number of Amps being drawn.

Handy to check what fuse rating a plug should have!

Mode 3 – Watts

Push the ‘Watt’ button and you’ll see the number of watts currently being consumed.
A 60W light bulb would show around 60 watts.

Use this mode to measure household items on standby. We found the following in our house:

13 watts – Sky+ on standby

9 watts – DVD Player on standby

9 watts – Lounge Stereo on standby

9 watts – Kitchen TV on standby

7 watts – VCR on standby

2 watts – Lounge TV on standby
Also use this mode to measure the consumption of things such as:

196 watts – Complete Computer System – Flat out processing video footage

138 watts – Complete Computer System – Just Reading Emails

90 watts – Lounge TV

70 watts – Pond pump and filter

53 watts – Cold Air Fan set to ‘Fast’

5 watts – TV Arial Booster

3 watts – Radio Alarm Clock

2 watts – Telephone Base Station

2 watts – Mobile Phone Charger

1 watt – iPod charger

Mode 4 – Hz

Push the ‘Hz’ button to see the frequency of your supply.

A normal UK reading is around 50 Hz.

Mode 5 – kWh (KiloWatt Hours) used

Push the ‘KWH’ button and you’ll see the number of kWh’s consumed since the monitor was last reset.

kWh is short for KiloWatt Hour and often abbreviated to just ‘unit’.
Your electricity bill will tell you your ‘Cost per Unit’.

In this example, 3.69 kWh’s have been used since the monitor was last reset.

For someone who pays 20p per unit, the cost of the electricity would be 20 x 3.69 = 74 pence.


Real Life applications

Typically you would use this mode for 2 types of test:

1) Calculate the cost for a particular task

As an example, say you wanted to find out how much the electricity costs to do a 60 degree wash.

Reset the monitor by switching it off and on. Push the KWH button and you’ll see 0.00 showing.

Plug the washing machine into the monitor and start the 60 degree wash.

If you were to watch the kWh display you would see the 0.00 start ticking up slowly as the electricity gets consumed.

Anytime after the wash has finished you can take a look at the monitor and you will see a value that will probably be around 0.5 kWh. This means you have used half a unit of electricity (half a kWh). You can look up the cost per unit on your electricity bill and work out the cost of the wash. e.g. half a unit at 20p per unit = 10p to do a 60 degrees wash.

While the wash is running you can change mode to Watts, Amps or any other and the kWh counter will still keep counting correctly.

2) Calculate daily running costs of fridges / freezers etc

Reset the monitor then plug in your fridge, freezer, dehumidifier, pond pump, electric blanket, air conditioner, computer, printer, monitor, television etc.

Let it run for 24 hours then take the reading from the monitor. From the kWh’s used reading it’s easy to work out the running costs per day, week, month & year.

Mode 6 – Hours

When you are in the ‘KWH’ display, push the ‘Hour’ button and you’ll see how many hours ago the monitor was last reset.

Great if you forget what time of day you started a 24hr test.

In this example, the monitor was reset 10 Hours 28 minutes ago.

Mode 7 – PF Power Factor

For advanced use. When you are in the ‘Hz’ display, push the ‘PF’ button you’ll see the Power Factor.

Read about Power Factor on the Wikipedia

Mode 8 – VA

For advanced use. When you are in the ‘Watt’ display, push the ‘VA’ button you’ll see the Amps multiplied by the Voltage.

VoltAmps are Amps x Voltage

Watts are Amps x Voltage x Power Factor


Purchase this meter

I found that my local Maplin store sold these power consumption meters

A great online resource for lots more power saving items and information is



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