Gas units to kWh converter

The formula

Suppliers convert gas volume to energy in a standard way. Take the units used (the difference between two readings). If your meter is imperial — it measures hundreds of cubic feet — multiply by 2.83 to get cubic metres. Then multiply by the volume correction factor of 1.02264, by the calorific value, and divide by 3.6 to turn megajoules into kilowatt-hours.

kWh = cubic metres × 1.02264 × calorific value ÷ 3.6

What the numbers mean

• Volume correction (1.02264): adjusts for the temperature and pressure of gas as it passes through the meter.
• Calorific value: how much energy each cubic metre of gas contains, in megajoules. It varies slightly by region and over time, generally between about 37 and 43 MJ/m³, and it is printed on your bill.
• 3.6: the number of megajoules in one kilowatt-hour.

Metric or imperial meter?

A metric meter shows "m³" on the dial; an imperial meter shows "ft³" or "cubic feet". If you get it wrong, your figure will be out by a factor of nearly three, which is a common cause of shock bills — check your meter type matches the one on your bill.

Worked example

Your readings show 150 units used on an imperial meter, and your bill gives a calorific value of 39.2. First convert: 150 × 2.83 = 424.5 m³. Then 424.5 × 1.02264 × 39.2 ÷ 3.6 = about 4,727 kWh. If the meter were metric, 150 m³ would give 150 × 1.02264 × 39.2 ÷ 3.6 = about 1,670 kWh, which shows why picking the right meter type matters.

Using the result

Multiply kWh by your unit rate to get the energy part of the bill, then add standing charges, the Climate Change Levy and VAT. The cost calculator adds these for you. Comparing your own readings with your bill is also a good way to spot estimated bills that have drifted away from what you've really used.