Units of electricity are used to measure the amount of energy that has been consumed at a property. Units of electricity are measured in kilowatt hours (kWh’s). Therefore one unit of electricity is equal to one kilowatt hour (kWh) of electricity used. Your electricity supplier will charge you an amount in pence for each unit (kWh) of electricity used.
(You are also charged a small fixed daily rate known as the standing charge. Read more about this in our Energy Bills Explained section).
What is the Cost of a Unit of Electricity in the UK?
This depends on the energy supplier and tariff that you are on. In 2015, rates in the UK typically vary between 9 pence per unit and 14 pence per unit. (Note that simply been on the lowest unit rate is not always the best option as you should also consider the standing charge and additional tariff features such as fixed rate periods, discounts and the service provided by each energy supplier. Our Energy Tariff Calculator will assess these factors for you).
How are Units of Electricity Measured?
Electricity meters are relatively straightforward compared to gas meters. This is because the number displayed on your electricity meter is in kilowatt hours (kWh), or Units. Therefore simply subtracting your old electricity meter reading from your current meter reading will tell you have many units you have used.
Current Meter Reading: (15th Mar 2015): 16480
Previous Meter Reading (15th Feb 2015): 16144
Units of Electricity Used: 336 kWh’s
What is a Unit of Electricity?
As explained previously, units of electricity are measured in kilowatt hours (kWh’s). One unit of electricity is equal to one kilowatt hour (kWh) of electricity used. So what is a kilowatt hour?
A kilowatt hour is equal to 1 kilowatt (or 1000 watts) of power being consumed continuously over a period of 1 hour. The amount consumed by an appliance or electrical item depends on the wattage of the appliance. The exact wattage figure will be displayed on all of your electrical appliances. Lets take a look at some examples below:
Toaster (1000 Watts or 1 Kilowatt kW)
- Let start with an example of a toaster rated at 1000 Watts. 1000 watts is the same as 1 kilowatt (kW).
- Used for 1 hour, this toaster will therefore use 1000 watts (1 kilowatt) of electricity. That’s 1 kilowatt of electricity used over the period of one hour. This is a Kilowatt Hour, or a Unit.
- You will therefore be charged for 1 unit of electricity on your energy bill. At a rate of £0.12 pence per unit, you will incur a £0.12p charge for using the toaster for 1 hour.
Oven (2000 Watts or 2 kW)
- A typical electric oven may be rated at around 2000 watts, or 2 kilowatts (2 kW)
- Used for 1 hour, the oven will use 2 kilowatts or power, or 2 units.
- Charged at £0.12 pence per Unit, you will be charged £0.24 pence for using the oven for 1 hour.
- Alternatively this could be viewed as using 1 unit of electricity every half an hour.
Electric Shower (8000 Watts or 8 kW)
- Electric showers are one of the biggest electricity consumers in the home typically with power ratings between 8 and 10 kW.
- 1 hours use will consume 8 kilowatt hours of electricity or 8 units.
- At a electricity rate of £0.12 pence per unit, thats £0.96 pence per hour (around £29 per month). In a property with 4 people, this could be adding up to a significant proportion of your electricity bill.
- Another way to look at this, is that you use 1 unit of electricity for every 7.5 minutes that the shower is in use.
Regular Halogen Light Bulb (60 Watts)
- Regular light bulbs (the non-energy efficient types), typically use between 40 watts and 60 watts of power. A higher wattage will mean a brighter bulb. In this example, we will look at bulb with a power consumption of 60 watts.
- 60 watts of power is equal to 0.06 kilowatts. (60 / 1000 = 0.06)
- Used for one hour this will therefore consume 0.06 kilowatts, the same as 0.06 units of electricity.
- 0.06 units charged at 0.12 pence per unit = £0.0072 pence. That’s less than 1 pence for an hour of use. (0.06 x 0.12 = £0.0072)
- This bulb would take 16.6 hours to use 1 unit of electricity. (1 / 0.06 = 16.6 hours)
Energy Efficient LED Light Bulb (5 Watts)
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