Reading Your Gas Meter: Calculating The Bill

This article will explain how to read a gas meter and convert it to kilowatt hours. 

Calculating the cost of gas 

While customers are billed in kilowatt hours, gas meters typically record the amount of gas consumed in cubic feet (ft3) or cubic metres (m3) (kWh). The formulas for calculating gas bills can be found in: 

The Regulations on Gas (Calculation of Thermal Energy) (SI 1996/439) 

The energy regulator, the Office of Gas and Electricity Markets (Ofgem), is in charge of these regulations. 

The steps below will show you how to read your gas meter (imperial or metric) and convert it to kilowatt hours. However, the Office for Product Safety and Standards is only responsible for the accuracy of gas meters, and billing issues should be addressed to the relevant supplier first. Citizens Advice consumer service will help you with this and provide you with unbiased energy supply advice. The Energy Ombudsman will investigate if your supplier is unable to settle your conflict. 

Imperial or metric measurements 

Despite the fact that all modern gas meters register in cubic meters, a large number of imperial gas meters (which register in cubic feet) are still in use to bill customers. The unit of measurement must be clearly marked on the register of the meter during the approval process for gas meters; for example

The part units of gas are outlined in red on a metric meter, and those digits are always divided by (i.e. to the right of) a decimal point. The part units on an imperial meter are often shown as a dial, as shown above. One complete revolution of the dial equals one cubic foot of gas consumption. 

Providing meter readings is an essential part of the job. 

Your gas supplier can read your meter on a regular basis. If your supplier is unable to do so for whatever reason, you can take the reading yourself and submit it to the supplier. It’s possible that submitting your own reading would save you the trouble of getting an estimated charge. 

A gas meter’s digits are read from left to right, and every red digit is ignored. However, any “zeroes” must be included in the reading given to the supplier, as seen in the following examples

Gas Bill Calculation 

The information on the gas bill itself would, in most cases, clarify how the bill was measured. Although the process used which differ slightly depending on the provider, it should be similar to the one outlined below. The Gas (Calculation of Thermal Energy) Regulations (SI 1996/439) specify all conversion factors. 

Step 1: To calculate the number of units used during the billing period, subtract your previous reading from your current reading. 

Step 2: Since the conversion factor from cubic feet to cubic meters is 0.0283, the following is the result: 

0.0283 cubic metres = 1 cubic foot 

2.83 cubic metres = 100 cubic feet 

To translate from hundreds of cubic feet to cubic metres, multiply the reading (in hundreds of cubic feet) by 2.83. (if the reading to the supplier was provided in cubic feet then this should be multiplied by 0.0283). Metric meters do not need this step since they are read directly in cubic metres. 

Step 3: The calorific value of the gas, which is a measure of the available heat energy, is then multiplied by this number. Calorific values differ, but the amount on your bill (for example, 39.5 megajoules per cubic metre (MJ/m3)) is an average of the gas delivered to your home (the regulations explain how this is calculated). Gas transporters must keep this figure between 38 and 41 MJ/m3, as figures outside of this range can trigger problems with gas-burning appliances. 

4th Phase 

The result is multiplied by 1.02264, as stated in the regulations. This adjusts the amount of gas to take temperature and pressure into account (as gas expands and contracts). 

Step 5: Finally, divide the figure by 3.6 to translate it to kWh. This aspect is also defined in the aforementioned regulations. 

Step 6: Multiply the amount of kWh by the price per kilowatt hour as shown on your gas bill. You could also charge a monthly fee or charge one price for the first ‘X’ units and a lower price for the remaining units. 

Additional Information 

Questions about reading the gas meter or billing issues should be addressed to the relevant supplier first. Creating account on will provide you with access to unbiased energy supply advice. The Energy Ombudsman will investigate if your supplier is unable to settle your conflict.

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