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Gas meter reading to kWh
Your gas meter measures volume, but your supplier bills you for energy. Enter two readings to see the kWh your business used, using the same conversion your bill uses.
Conversion per the Gas (Calculation of Thermal Energy) Regulations 1996: volume × 1.02264 × calorific value ÷ 3.6. Imperial meters are converted at 2.83 m³ per 100 cubic feet. Cost estimates exclude the standing charge, Climate Change Levy (0.801p per kWh from 1 April 2026) and VAT.
How gas units become kWh
Your gas meter measures the volume of gas that passes through it. Your supplier charges for the energy in that gas, in kilowatt hours. Four steps turn one into the other, and every UK gas bill shows them:
- Units used. Current reading minus previous reading.
- Convert to cubic metres. Metric meters already read in m³. Imperial meters read in hundreds of cubic feet, so multiply by 2.83.
- Apply the volume correction factor. Multiply by 1.02264. This adjusts for temperature and pressure so every customer is billed on the same basis.
- Apply the calorific value. Multiply by the calorific value in MJ/m³, then divide by 3.6 to convert megajoules to kWh.
As a rough check, one cubic metre of gas is a little over 11 kWh, and 100 cubic feet is about 31 kWh.
The full explainer goes through each step with worked examples for both meter types, and explains where the calorific value comes from.
Using this to check a bill
Convert your own readings, then compare the kWh with the figure your supplier billed. Small differences are normal, because the calorific value changes daily and your bill uses a weighted average across the period. A large difference usually means one of three things: the bill was estimated, the readings were transposed, or the meter type was recorded wrongly when the account was set up.
Once you know your kWh, the cost calculator turns it into an annual bill with the Climate Change Levy and VAT, and you can compare that against what other businesses your size pay. In Q2 2026, the smallest business gas users paid an average of 9.31p per kWh all in, before VAT.
If the numbers look wrong and your supplier disagrees, the complaints process sets out what to do, including the eight-week deadlock point.
Gas conversion FAQs
How do you convert gas units to kWh?
Take the units used between two readings. If your meter is imperial, in hundreds of cubic feet, multiply by 2.83 to get cubic metres. Multiply the cubic metres by the volume correction factor of 1.02264, then by the calorific value on your bill (around 39 to 40 megajoules per cubic metre), then divide by 3.6. The answer is kWh.
What is the volume correction factor?
A fixed factor of 1.02264 that adjusts the gas volume your meter measured to standard temperature and pressure, so that everyone is billed on the same basis. Every UK gas bill uses it.
What is the calorific value of gas?
The energy content of the gas delivered to your area, in megajoules per cubic metre. It moves slightly day to day and is printed on your bill. National Gas publishes the daily figure for each of the 13 local distribution zones, and it is typically between 37.5 and 43.0 MJ/m³ under the Gas (Calculation of Thermal Energy) Regulations.
Is my gas meter imperial or metric?
Metric meters measure in cubic metres and usually say m³ on the dial, with five digits before the decimal point. Imperial meters measure in hundreds of cubic feet, often say ft³, and usually show four digits. If yours is imperial, the conversion needs the extra 2.83 step.
Why does my bill show more kWh than my meter reading?
Because the meter measures volume, not energy. A cubic metre of gas contains roughly 11 kWh of energy, so the kWh figure on your bill is always much larger than the units on the dial.
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