Energy bills explained

Energy bills explained

Energy bills can be difficult to understand, with even simple things like how much you're paying seemingly hidden.

YouGov research on behalf of uSwitch found 75% of people find energy bills confusing, and only 4 in 10 could understand the calculations on their bill.

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Help me read my bill

We've put together a sample of the most popular suppliers' gas and electricity bills. These energy bill breakdowns might not look exactly like yours — because you may pay differently than the sample or only have one fuel — but the bill layout for your supplier should generally be the same, making it easy to spot key items like your annual consumption, plan name, cancellation fee info and unit rate.

British Gas energy bill sample (dual fuel, pay on receipt)

EDF Energy bill sample (dual fuel, direct debit)

E.ON Energy bill sample (dual fuel, monthly direct debit)

npower bill sample (dual fuel, monthly direct debit)

ScottishPower bill sample (dual fuel, monthly direct debit)

OVO bill sample (dual fuel, monthly direct debit)

Still have questions about your bill? Check our Energy bill jargon buster section for definitions for everything from "calorific value" to "NSC".

Energy bills explained video

  • Read the Transcript

    Energy bills can be hard to make sense of. Our research shows that as many as 75% of us find them confusing , and it's really tempting just to shove them in a draw and forget about them. But it's important to take a good look at them when you get them, and it doesn't need to be hard to do. You just need to know what to look out for.

    Is it an estimated bill?

    You can find this out by looking at the summary section which is usually on the first page of your bill. If there's an 'e' or 'estimated' next to this amount it means your bill is based on estimated meter readings, rather than actual ones.

    If this is the case you should take a meter reading and send it to your supplier to ensure you get fully accurate bills.

    Has your last payment been received?

    The summary section will also tell you how much your last payment was for and when it was received.

    Full breakdown of your bill

    Is your bill any different to normal? The full breakdown of your bill is usually on the second page and will show you your tariff name and how much you pay for electricity and gas per kWh.

    If any of these details have changed you should think about the impact it has on your bill. For example, if your tariff name has changed it could mean that an old deal your on has expired or that unit rates have gone up. This could lead to higher bills and it could mean it's time to come to uSwitch and make sure you're still on the best deal for you.

    What other information do you need if you want to switch supplier?

    Next let's look at the bits of information on your bill if you want to switch energy supplier. Your supplier's name, your electricity supply number of MPAN, the name of the tariff you're on, your gas meter number or MPRN, and the amount of electricity and gas you've used in kWh.

    Annual energy statement

    Finally keep you eyes peeled for your annual energy statement. Your supplier is now required to send you one of these and it will tell you the name of the tariff you're on, how much energy you've used over the last year, and how much your energy will cost you over the coming year; everything you'll need to make sure you're on the absolute best deal.

Energy bills jargon buster

Our glossary lists all the terms you're likely to find, either on your bills or across our site. Simply click on the term you need explained and we'll tell you what it all means.

Account number

Your account number refers to the account you hold with your energy supplier. This number will be printed on your bill and you will be asked to provide it when you contact your energy supplier.

Calorific Value (CV)

'Calorific Value' (CV) is a scientific term used to describe how much heat is generated when a known volume of gas is completely burned away.

Gas passing through the National Grid has a CV of 37.5MH/m3 to 43.0MJ/m3, but the CV for your specific area should be displayed on your gas bill.

Put simply - the CV measures how 'useful' your gas is, so your supplier can charge you based on the quality of the gas that is supplied to you.

For more information on calorific values and how they're calculated, please refer to the National Grid website.


If you have any discounts applied to your energy bills, they should be marked clearly near the final total. There is a large range of discounts available (common examples include dual fuel discounts and direct debit discounts), so if you're not sure which discounts you're entitled to, you can run through our energy calculator and check your current plan details or contact your energy supplier for more information.

Dual Fuel

Dual fuel is where you receive your gas and your electricity supply from the same energy company. Read more about dual fuel.

Economy 7

Economy 7 is a type of electricity tariff that uses different prices for the electricity you use during the day and the electricity you use during the night.

Typically the electricity you use at night will cost you less than electricity used during the day. With Economy 7, the 'night' usually refers to the early hours, between around 1am to 8am, but these hours can vary between suppliers. Read more about Economy 7.

Economy 10

This structure gives you three off-peak hours in the afternoon, two in the evening and five hours overnight. The designated hours will change between suppliers. Unfortunately we cannot support economy 10 switching on uSwitch.

Read more about economy 10 tariffs here.

Estimated (E) or actual (A) readings

If your meter reading has been estimated - then your energy supplier has assumed your usage for the period in question, based on your energy usage patterns in the past.

If they don't hold this information, they will use national average figures. If you've had a meter reading recently, then your usage will be marked as 'actual' and not estimated.

This isn't always obvious - and might only be denoted by a capital 'A' for 'actual' or 'E' for 'estimated'.

Not sure how to take a meter reading? Read our guide on taking a gas or electricity meter reading.

Fixed Monthly Direct Debit (MDD)

If you hold a monthly direct debit with your supplier, then you will pay a set amount to your supplier every month. However this does not mean that your energy prices are fixed.

Your energy supplier needs to give you notice if they intend to change the amount of the monthly direct debit.

How to convert units to kWh

On your energy bill, your gas units will be converted to kilowatt hours. Please note that the Calorific Value will change depending on your area - so please check your bill for the correct figure.

Use the following formula to convert units to kWh:

Total units used x metric conversion factor (2.83) x volume correction factor (1.02264) x calorific value /kilowatt hour conversion factor (3.6).

This works for meters that record hundreds of cubic feet where your gas meter shows 'ft3' next to the reading. If your meter measures in cubic meters with an 'm3' next to the reading, then go through the same sum while removing the metric conversion factor of 2.83.

Example for meter that records hundreds of cubic feet:

unit x 2.83 x 1.02264 x 39.1 / 3.6 = 31.43 kWh

IGT Network/charges

IGT stands for 'Independent Gas Transporter'. If your home is supplied by an Independent Gas Transporter Network, it means that it is not connected to the National Grid, which supplies most of the UK's home's with gas.

You will often find an extra charge applied to your bill if you are supplied by an IGT network, due to the extra costs involved in having your gas delivered.

If your MPRN number is 10 digits long and begins with 74 or 75 then you are supplied by an IGT.

Kilowatt hours (kWh)

A kilowatt hour is the standard measurement of energy that your energy supplier will use to bill you. A kilowatt hour refers to a person using 1000 watts of electricity for 1 hour. Your prices will be set per kilowatt hour (kWh) of energy you use.

Loyalty points

Loyalty points will only apply to certain tariffs, and can come in different formats. These can include things like Sainsbury's Nectar Points and Tesco Clubcard points, which can be earned on energy bills with suppliers that have a commercial arrangement with specific supermarkets. The number of points you've accrued should be displayed clearly on your bill.

Meter point administration number (MPAN)

Your meter point administration number will often be referred to as your MPAN or your supply number. It can also be referred to as your 'S' number. This number is assigned to the electricity meter at your property to identify it, and can be found on your electricity bill. It is displayed in a very specific format as pictured below:

Supply number
If you can't find your supply number anywhere, your energy supplier should be able to help you.

Meter point reference number (MPRN)

Your meter point reference number will often be referred to as your MPRN number. This number is assigned to the gas meter at your property, and can be between 6 and 10 digits long.

On your bill this number may be referred to as an 'M' number, but if you can't find it you can call the Meter Number Helpline on 0870 608 1524 for help.

Metric conversion factor

An imperial to metric conversion factor of 2.83 is used in the calculation to convert units into kilowatt hours (kWh).


MPRN is the abbreviation for meter point reference number and MPAN is the abbreviation for meter point administration number. Please see above for further details on what this means.

NSC - No Standing Charge

If you plan name includes the abbreviation 'NSC' or the words 'No Standing Charge', then your supplier does not apply a fixed charge to your plan.

Plan/tariff name

The name of your energy plan identifies which tariff you are on, which in turn dictates the prices you are charged. There are hundreds of different plans available in the market, and naming conventions will differ between suppliers.

Standing charges

Some energy plans include a standing charge, where a fixed charge is applied to your bill. This does not necessarily mean that the plan is more expensive than a no standing charge plan, as the kilowatt hour(kWh) rates can be lower.

Standing Order

If you hold a standing order with your energy supplier, you have arranged for a fixed amount to be sent from your bank account to pay your energy bill as often as necessary.

You have control of this payment method, so your energy supplier cannot change the payments at their end, even with your permission.

Supply number

Your supply number can also be referred to as your MPAN or electricity meter point administration number.


Sometimes your gas and electricity prices are charged using different 'tiers' on your energy bills. This means that you get charged at one rate until you've used a certain amount of energy, and then at a different rate for any energy used over that level.

Plans that include a standing charge won't tend to have different tiers, whereas no standing charge plans will, as this is their way of introducing a type of minimum charge.


Although your gas will be charged according to kilowatt hours (kWh) used, your gas will initially be measured in units. This is then converted to kilowatt hours on your bill using a standard formula. Find out how to convert kWh's into units.

Variable Direct Debit (VDD)

If you have a variable direct debit set up with your energy supplier, then you are giving them control over the direct debit. They will amend the amount taken each month to pay off the outstanding bill, and they do not have to give you notice before changing the amount.


VAT will be charged on top of your total bill at a standard rate of 5% instead of the usual 20%. It is important to note that your gas and electricity bills will show all unit prices before VAT, whereas uSwitch is required to display all unit prices with VAT included. This allows us to make the most accurate and relevant comparison for you.

Volume correction factor

The volume correction factor of 1.02264 takes into account the changes in the volume of gas based on temperature and pressure.

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Read more…

  • Utility Bills Your utility bills may not make pleasant reading, but they contain vital information
  • Annual Energy Statements Your annual energy statement holds the secret to saving money on your bills
  • Household Bills Household bills can be tricky to decipher, but understanding what your reading is the key to saving money

Switch today and never overpay on your energy bills again!

Save up to £383/yr and we'll make sure you never pay too much