From cubic metres to kWh
Most business gas meters measure volume in cubic metres or, on older meters, cubic feet. To calculate your bill, the supplier converts this volume into kWh using a calorific value, which reflects the energy content of the gas, and a volume correction factor that adjusts for temperature and pressure.
The standard formula is: cubic metres multiplied by the volume correction factor, multiplied by the calorific value, divided by 3.6, giving the equivalent kWh. This figure is then multiplied by your unit rate to calculate the energy cost portion of your bill.
Typical business gas price per kWh
| Business profile | Price per kWh |
|---|---|
| Micro business | 8p - 11p |
| Small business | 7p - 10p |
| Medium business | 6.3p - 9p |
| Large / daily metered business | 5.3p - 8p |
Worked example: cubic metres to a bill
Suppose a meter reading shows 500 cubic metres used in a month. Using an illustrative volume correction factor of 1.02264 and a calorific value of 39.5, the calculation is 500 multiplied by 1.02264 multiplied by 39.5, divided by 3.6, giving approximately 5,613 kWh.
If the agreed unit rate is 7p per kWh, the energy cost is 5,613 multiplied by 7p, giving approximately £393. Adding a standing charge of, for example, 35p per day for a 30-day month adds £10.50, giving a total before VAT of around £403.50.
Compare business energy prices
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Pence per kWh vs price per cubic metre
Some historical bills or comparisons quote a price per cubic metre rather than per kWh, which can make direct comparison confusing. Because a cubic metre of gas contains more energy than one kWh, a price per cubic metre will always be a higher number than the equivalent price per kWh, so always check which unit a quoted figure uses before comparing.
Why your gas price per kWh may differ from a quote
The calorific value used in the conversion can vary slightly by region and over time, which means the exact kWh figure calculated from the same volume of gas can differ marginally between bills, even where the unit rate itself has not changed.