Gas Meter Readings And Bill Calculation

How to read your gas meter and convert this reading to kilowatt hours.

Gas meters generally record the volume of gas consumed in cubic feet (ft³) or cubic metres (m³) although consumers are billed in kilowatt hours (kWh).

While the actual method used may vary slightly depending on the supplier, the method should be similar to that shown below:
Number of gas units   x   Conversion Factor   x   Calorific Value   x   Volume Correction    ÷   kWh Conv   =     kWh  
 
Start:         Select Meter Type:         Select Value**:                              
End: *                                                      
Used:     x         x         x     ÷     =    
                                                         
Unit Price / kWh           # of kWh           Cost   or   If vat is not included in the 'Unit Price'  
      x         =             ( + vat     =     )
*** Standing Charge           # of days           Cost   or   If vat is not included in the 'Unit Price'  
      x         =             ( + vat     =     )
Totals
* If you have specific number, just enter that figure here and leave the 'Start:' figure as 0.
** Don't worry if you do not know this figure as the default (39.2) will be used. It will only make any calculation a few pence out.
*** You do not have to complete these two SC boxes, but if you do it gives the total cost of your gas charges.

The following steps explain how to convert the meter reading to kilowatt hours (which is done for you above) , but is shown here for information only:

  • Step 1

    • Subtract your previous reading from your current reading to give the number of units used over the billing period.

  • Step 2

    • The conversion factor from cubic feet to cubic metres is 0.0283 therefore:

      • 1 cubic foot = 0.0283 cubic metres

      • 100 cubic feet = 2.83 cubic metres

      For imperial meters the reading (in hundreds of cubic feet) is therefore 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). This step is not required for metric meters as they are read directly in cubic metres.

  • Step 3

    • This figure is then multiplied by the calorific value of the gas which is a measure of the available heat energy. Calorific values vary and the figure quoted on your bill (eg 39.5 megajoules per cubic metre (MJ/m³)) will be an average of the gas supplied to your property (the regulations explain how this is calculated). Gas transporters are required to maintain this figure within 38 MJ/m³ to 41 MJ/m³ as figures outside of this range will cause problems with gas burning appliances.

  • Step 4

    • The figure is then multiplied by 1.02264 as prescribed in the above regulations. This corrects the volume of gas to account for temperature and pressure (as gas expands and contracts).

  • Step 5

    • Finally the figure is converted to kWh by dividing by 3.6. Again, this factor is prescribed in the above regulations.

  • Step 6

    • The number of kWh is then be multiplied by the price per kilowatt hour as detailed on your gas bill.