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Gas meters and electricity meters - what you need to know

By Sarah Ingrams

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Gas meters and electricity meters - what you need to know

Find out how gas and electricity meters work, how you can spot if yours is faulty and how you can use your electricity meter to save money.

Everything you need to know about your gas meter and electricity meter, including how to save money and how smart meters differ. Plus, we reveal how to check if your gas and electricity meter is faulty, as your energy company could owe you money.

Gas and electricity meters are the key to you getting accurate bills, as they measure the amount of energy you use. Learning how to read your gas meter and electricity meter, and finding out how they work, will help you be more in control of your energy bills - and could help you save money in the long term. 

Some suppliers ask you to provide regular meter readings, some get automatic readings by using smart meters, while others estimate your bills or send staff to read the meter for you.

But whatever your meter or supplier, regularly reading your gas and electric meters will make your bills as accurate as possible. And you'll also need to read your meters if you move home or switch gas or electricity supplier.  

Don't pay your energy firm more than you should - find out if you could save money with our energy switching site, Which Switch. Compare gas and electricity prices.

How to identify your gas meter and electricity meter 

Not sure what type of gas and electricity meter you have? Scroll through the images to see the main types of gas and electric meters in the UK. 

Standard gas and electricity meters

There are lots of different types and designs of gas and electric meter. But all should clearly display a set of numbers indicating your latest energy usage.

They also have a unique identification number - a Meter Point Reference Number (MPRN) for gas and a Meter Point Administration Number (MPAN) for electricity - which will be displayed on your bills.

Your energy supplier must read your meter every two years, but we recommend you submit your own meter readings every three months. Take a note of the reading and the date when it was taken. If you can't find a pen and paper, take a photo using your smartphone. 

Find out some simple ways to save money - go to how to save on your energy bill.

Is your energy meter faulty?

A Which? investigation (see Which?, March 2016) discovered that hundreds of thousands of gas and electricity meters in Great Britain could be faulty - meaning customers could be owed a lot of money. We've analysed Government figures, our own survey results and looked at confidential industry reports to investigate the scale of the problem. 

Meters running too fast or slow

Gas meters approved under UK law must be within 2% accurate and electricity meters within +2.5% and -3.5% accurate. 

Government figures show:

  • On average, 24% of the gas meters tested every year since 2006 (21,243 meters tested in total) were faulty
  • 7% of the 2,345 electricity meters tested since 2003 were faulty, installed incorrectly or not an approved type

These are disputed gas and electricity meters – only tested because an error is already suspected – so the figures are not representative of Great Britain’s 53 million meter population as a whole.

We’ve also seen three confidential National Grid reports that suggest the figures could be between 14% and 18%. National Grid said its figures were also not representative of the overall meter population.

Meters telling the wrong time

There are 3.9 million households in Great Britain on a time-of-use tariff, such as Economy 7, which get cheaper electricity at certain times. 

But we’ve found that 16% of Which? members on one of these tariffs have found their meter clock is wrong (survey of 427 Which? members in Spring 2014). 

If that was true across the whole population, it would mean that 624,000 meters could be wrong. We’ve heard from people who have been overcharged hundreds of pounds due to this type of fault.  

What to do if you suspect your gas meter or electricity meter is faulty

Unusual bills or meter readings are usually the best clue to a faulty meter. If you’re on a time-of-use tariff, you should be able to check the clock on your meter or see if the rate changes when it should.

If you suspect your meter is faulty, then you should record regular meter readings to help prove your case. You could also try turning off all your appliances and watching the meter. It shouldn’t still be registering significant amounts of energy.

And it's worth investing in an energy monitor to view your real-time energy use. Although this isn’t a fool-proof way of checking meter accuracy, it can be a good guide if you already have suspicions.   

Your gas meter and electricity meter rights

Energy suppliers have a legal obligation to ensure all gas and electricity meters are accurate. If you suspect your meter is faulty, first contact your supplier – it is required to investigate.

Meters can be tested at your home or sent away to an independent laboratory. The actual testing is free but suppliers can charge for the cost of removing and replacing your disputed meter. Find out more in our consumer rights guide to faulty meters.

Things you probably didn't know about gas meters and electricity meters 

Did you know you’ll probably get more gas for your money if you live at sea level rather than at the top of a mountain? And did you know you’re likely to get a better deal if your gas meter is outside? Here we look at how gas is really measured.

Calorific value (CV) calculations

The calorific value – or heating value – of gas varies depending on where in the country you live. It also varies from day to day. The country is divided into 13 different charging areas (known as local distribution zones) and customers’ bills are based on their area’s average daily calorific value for the billing period.  


Gas expands and contracts with heat. Bills are based on a temperature of 15°C. So those with meters outside can benefit, compared to those with meters inside.


The volume of gas increases in low pressure. Bills are based on 1,013.25 mbar. So properties at a much lower altitude than average are likely to benefit. Billing assumes a height above sea level of 67.5m.


Most consumers’ bills will be slightly inaccurate because the assumptions about temperature and pressure are fixed for the whole country. An independent report produced for the Government shows that: in 2011 the postcode with the smallest error was PE11 (in Lincolnshire), and the one with the largest error was BD6 (Bradford). 

Assuming an average annual gas bill of £750, this is equivalent to under-billing of £11.77 and over-billing of £18.58.

Economy 7 electricity meters

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If you're on an Economy 7 electricity tariff, you will have a special meter that provides two different readings: 

  • one for more expensive electricity used during the day
  • the other for cheaper night usage. 

For some Economy 7 meters, the higher rate will be displayed as 'normal' on your meter. Your cheaper night time rate will be displayed as 'low' on your meter. 

If your meter is digital, Rate 1 will represent your cheaper night-time usage and Rate 2 your more expensive daytime usage.

Which? has discovered that many Economy 7 users may not be making the most of their tariff. If you use less than 30% of your electricity during your cheaper night time hours, then you might be better off switching to a single electricity tariff - click on our news story to find out more.

We also found that some people have Economy 7 meters with incorrect clocks, meaning they can't always make the most of their cheaper off-peak hours. Contact your energy supplier if you are unsure of your cheaper hours or think your meter clock is wrong.

Prepayment energy meters

To use a prepayment meter, you'll need to go to a retail outlet to charge (add credit) to your card or key, or to buy tokens. Your charging device is then inserted into the front of your prepayment meter.

The display window on the front of the meter can show a range of information including: 

  • Units of energy consumed
  • Any fixed charge the energy supplier charges
  • The rate per unit of fuel
  • The amount of credit inserted
  • Current credit
  • Any outstanding debt
  • Any debt repayments
  • Emergency credit.

When the energy meter runs out of credit, the gas or electricity supply is automatically stopped.

You'll be sent energy statements either quarterly or annually. These will show how much energy you've used and at what price, any debt that has been paid back, and any outstanding debts and meter readings.

Smart energy meters

Smart meters enable energy suppliers to remotely record how much electricity and gas you're using - doing away with the need for estimated bills and meter readings. The government is rolling out smart meters nationally between 2016 and 2020. 

Your energy company will contact you to arrange installation of a smart meter. Some energy companies - such as British Gas and First Utility - have already started to install smart meters.

Smart meters acting dumb

Sometimes smart meters can’t send automatic readings back to the supplier and start acting 'dumb'. Government figures released in June 2017 showed more than 330,000 smart meters have lost their smart abilities.

This could be due to technical problems. For example, the meter being unable to communicate externally or customers switching to a supplier that can’t operate the meter in smart mode. 

Find out what the smart meter roll-out will mean to you, including whether you can refuse a smart meter - see our guide to the smart meter roll-out

Save on your energy bills with Which? Switch

Our Which? Switch customers are currently saving an average of £237 a year on their gas and electricity bills.  This is an average figure, so many customers could save a lot more.

This figure is the average estimated annual saving for customers who applied to switch suppliers through Which? Switch between 1 November 2016 and 30 April 2017.

Use Which? Switch to find a cheap energy deal.