The most common types of electricity meters are single-rate digital meters, variable-rate digital meters and dial meters.

Single-rate digital electricity meters

Electricity meters measure energy use in kilowatt hours (kWh). A single-rate meter has one set of numbers to refer to.

1. Write down all the numbers before the decimal point, from left to right.

2. Ignore any numbers after the decimal point (which may be shown in red).

Dial electricity meters

This type of meter shows a series of clock-style dials with numbers from zero to nine. Each dial turns in the opposite direction to the dial before it.

Some meters show a series of clock-style dials

1. To take a reading, start with the left dial and write down the number indicated by the pointer on each dial, moving towards the right.

2. If the pointer is between two numbers, record the lower of the two. If the pointer is between nine and zero, record it as nine.

3. Ignore any red dials.

Variable-rate electricity meters

Economy 7 or White Meter meters have two displays (or the ability to switch between two different displays) with readings for daytime and night energy use. The display marked 'low' or 'night' shows how many units of off-peak electricity you've used. The display marked 'normal' or 'day' shows how many units of peak electricity you have used.

1. To take a reading, write down the numbers from both displays, ignoring any figures in red.

Economy 7 meters have the capacity to display two readings

2. Economy 10 meters have an additional display to record the electricity you use during three different time periods instead of two - including daytime use.

Find out more about Economy 7 and Economy 10 in our energy tariffs explained guide. We've also got practical tips on reading your gas meter.

Finding your electricity supply number

If you're switching electricity suppliers, your new company will supply electricity using your existing meter and cabling. If your exact meter can't be located during switching - if you live in a new-build property, for example - we'll ask you for your meter point administration number (MPAN), also known as your 'supply number' or 'S' number.

This is a unique number that identifies the correct meter at your property and is different to the serial number printed on the meter itself.

You will find your MPAN on your electricity bill, not on the meter itself. Look for a large 'S' and a grid of numbers. The bottom row of numbers (13 digits) is all we need to ensure that your switch happens as smoothly as possible. If you can't find it, you should contact your current electricity supplier.

Once you've found your MPAN, compare energy prices with us and start your switch today.

Cut your energy bills with Which? Switch

The average saving when switching gas and electricity is £191 - compare gas and electricity tariffs now to find the best deal for you.

This figure is the average estimated annual saving for customers who applied to switch suppliers through Which? Switch between 1 January 2014 and 30th June 2014.

More on energy...

• Find out how to read your gas meter
• Read our tips on moving house and energy supplier