How to convert gas meter readings units - gas M3 to kWh

It's really important to take and regularly send accurate gas meter readings to your energy supplier – if you don’t know how to use your meters correctly, you can’t be sure you’re getting billed correctly.

Most electricity and gas suppliers will estimate your energy usage, but if you regularly provide them with accurate gas meter readings, you’re more likely to pay for the energy you actually used, rather than for your suppliers’ best guess.

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Energy suppliers measure gas units in kilowatt hours (kWh), but your meter might show your usage as cubic feet (ft³) or cubic metres (m³), in which case you'll need to convert your gas units to kWh from m³ or ft³.

We'll show you how to do the working out a bit later, but the simplest way to convert m3 to kwh is to use our gas meter reading calculator below.

Just choose the type of meter you have - imperial meters show readings in ft³ while metric meters show readings in m³ - and input the figure in the box. Our gas conversion tool will then convert the gas units to kwh and give you an exact figure, so you can make sure you’re being charged correctly for what you use and the readings you have.

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Gas units to kWh converter

What type of meter have you got?

Number of units used:

Your gas usage in kWh:

For imperial meters, the reading is in hundreds of cubic feet (100 ft³), so if your meter shows a usage of 1, you've actually used 100 ft³.

Your reading is then multiplied by 2.83 to convert to cubic metres (if the reading to the supplier was provided in cubic feet then this should be multiplied by 0.0283).

If you need any further help reading your gas meter, take a look at our Gas and electricity meter readings page.

Why do you need to take a gas meter reading?

It's important to take accurate gas meter readings to avoid over or underpaying for your energy.

If you don’t give regular readings, your supplier will base your bills on how much gas it assumes your using, and this estimate can be inaccurate, to the point where it costs you money - overpaying could mean you struggle to pay your energy bills, while underpaying could quickly see you fall into debt with your energy supplier.

It’s also really handy to know how much you actually use so that you’re more capable of switching suppliers once your contract is up.

And you also need to be aware of what type of gas meter you have, to ensure you’re being charged correctly. If you're considering an energy switch, it’s always good to know what types of meters you have and let your supplier know.

What are the different types of gas meter?

Below are illustrations and examples of gas meter types. This will help you better identify your own meter at home. It will be either an imperial or a metric gas meter.

Imperial gas meters

If your meter is an old imperial gas meter, which will measure gas in cubic feet, it will have the words "cubic feet" or the letters ft3 shown on the front of the meter. imperial gas meter

Metric gas meters

If your meter is a newer metric meter, which measures gas in cubic meters, it will state "cubic meters" or display M3 on the front of the meter. metric gas meter

How gas readings differ from electricity readings

Electricity consumption is usually shown in kilowatt-hours (kWhs) on your meter and bill, but gas can be referred to as either units on your meter, or kilowatt-hours on your bill. If you’re unaware of this, it can lead to confusion.

To help you better understand your gas usage in relation to how much you're being charged, the gas meter reading calculator at the top of the page works out the gas coversion in units to kWh. All you have to do is include whether you have an imperial or metric meter and how many units you've used. The calculator will do the rest of the work for you!

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What to do with your gas meter readings

Once you have recorded your meter readings, check your last bill and see what the estimated reading was. If the true number is smaller than the estimate, then you have been overpaying. In this case, you’re entitled to a refund from your gas company, and it’s worth checking out How to get a refund from your energy company.

If you have been underpaying then the sooner you contact your supplier the better. You will need to increase your Direct Debit payments or pay it off in one go if it is a small amount, but the quicker you contact the supplier, the less debt you will accumulate. Once you've paid off what you owe, you can search for a cheaper supplier.

If you are closing your account with your current supplier, you will need to send them an accurate meter reading. You’ll also need to submit readings to your new supplier to make sure your new bills are accurate.

The suppliers often have a dedicated phone line you can call to provide your own meter readings. This number should appear clearly on your bill. Some companies will automatically send you a fresh bill based on your reading.

What’s the volume correction factor, when converting gas units to kWh?

The volume correction factor is used to take into account the temperature, pressure and atmospheric conditions at a property. This factor is typically 1.02264 unless your household has unusual atmospheric conditions. You can usually find this number on your gas bill.

What is a calorific value, when converting gas units to kWh?

A calorific value (CV) is a measurement of the amount of energy contained in gas, measured in megajoules per cubic meter (MJ/m cubed).

The CV of the gas at each Local Distribution Zone is continually measured by the National Grid who sends this figure to your gas supplier, who then uses it for their calculations. Typically, a gas supply has a CV between 37.5 and 43.0 MJ/m cubed. You can use 40.0 as a default number if you don’t have the exact figure.

How to switch energy supplier

How to switch energy supplier with UKPower. Simply enter your postcode and we'll compare energy prices from a range of suppliers. You then choose the one you prefer and we'll take care of the rest.


Once you know how much gas you're using, you can compare gas and electric deals to see if you can find a cheaper deal elsewhere.

UKPower's energy comparison tool can compare deals from a wide range of suppliers in minutes, all you need to do is choose the one you like best and we'll handle the rest of the energy switch for you by letting your current supplier know you're leaving and telling your new provider you'll be joining them.

The switch will be complete within 21 days, and there'll be no digging or drilling at your property, as your gas will be supplied through the exisiting pipes.

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