A gas meter usually measures the volume of gas that passes through it. Your supplier calculates the difference between readings, may adjust that volume to standard billing conditions, and uses the gas’s heat content to express the result as energy—such as kilowatt-hours (kWh) in the UK or therms in some U.S. billing contexts. The units and exact calculation depend on local rules and your supplier.
What a gas meter measures
Most gas meters register volume, not the amount of heat energy in the gas. The register is marked in cubic metres (m³) or cubic feet (ft³). A reading is a cumulative total; to find gas used over a billing period, subtract the previous reading from the current one. The UK Office for Product Safety and Standards explains these units and the distinction between meter readings and bills in its gas meter readings and bill calculation guidance.
Metered volume is the gas volume at the pressure and temperature where it passes through the meter. Because gas volume changes with pressure and temperature, a utility may convert that reading to a defined billing or standard volume before calculating energy. This distinction is described in the U.S. Department of Defense’s Natural Gas Handbook.
Why the meter and bill can use different units
A meter records volume, while a bill may charge for energy. The conversion depends on how much heat the gas contains, commonly represented by a calorific value or heat-content factor. Heat content varies by location, customer type, and time, so one conversion factor should not be assumed to apply everywhere.
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- UK example: household meters generally record cubic feet or cubic metres, while household bills are expressed in kWh under the UK guidance.
- U.S. example: gas prices may be expressed per therm, MMBtu, or cubic foot. The U.S. Energy Information Administration (EIA) reports that natural gas delivered to U.S. end-use sectors averaged about 1,037 Btu per cubic foot in 2025. At that annual average, 100 cubic feet corresponds to 103,700 Btu, or 1.037 therms; 1,000 cubic feet corresponds to 1.037 MMBtu, or 10.37 therms. A household’s local heat content may differ. See the EIA’s natural gas unit conversion explanation.
How a UK meter reading becomes kWh
The UK Office for Product Safety and Standards gives the following calculation as guidance for converting a meter reading to energy. It is a UK example, not a universal formula.
- Subtract the previous meter reading from the current reading to find the volume used during the period.
- If an imperial meter registers hundreds of cubic feet, multiply the volume used by 2.83 to convert it to cubic metres.
- Multiply the cubic metres used by the calorific value shown for the calculation. The UK guide’s example uses 39.5 MJ/m³; it says gas transporters must maintain the figure between 38 and 41 MJ/m³ under the arrangements described in that guidance.
- Multiply by 1.02264 to account for temperature and pressure, then divide by 3.6 to convert megajoules (MJ) to kWh.
- The supplier applies the relevant unit rate to the resulting kWh and adds any applicable standing charge or tiered pricing.
The 2.83 conversion, 1.02264 factor, and calorific-value example are the figures in the UK government’s published guidance, dated 10 June 2014. Check your own bill and supplier’s explanation for the factors used for your supply.
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How to read the register accurately
In the UK, a metric meter registers cubic metres and an imperial meter registers cubic feet. The unit is marked on the meter. UK guidance says to ignore red fractional digits when submitting a reading and to include zeros in the whole-number reading. Display conventions and submission instructions can differ elsewhere, so follow your supplier’s local instructions. Submitting a reading can help avoid an estimated bill.
What standard or billing volume means
Standard or billing volume is a measured volume converted to defined pressure and temperature conditions. This allows gas quantities to be compared or billed on a consistent basis even when the conditions at the meter differ. The U.S. Department of Defense handbook identifies 14.73 pounds per square inch absolute (psia) and 60°F as common natural-gas industry base conditions, and notes that some utilities use 14.65 psia. These are technical conventions, not a statement that every residential utility uses the same base.
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At higher pressures, gas behavior can depart from the ideal-gas assumption, which is why compressibility corrections may also be needed. Canadian regulations provide one legal example: standard volume is calculated using registered volume, pressure and temperature multipliers, and the square of a supercompressibility factor. That formula does not mean every small household meter performs the same correction itself. The handbook distinguishes larger installations, where pressure and temperature are generally monitored and recorded, from small diaphragm meters.
Do household meters measure energy directly?
Do not assume that the meter display shows the gas’s energy content or that every household meter independently applies every billing correction. The UK guidance describes converting volume to kWh using prescribed factors, while the U.S. handbook discusses equipment and corrections that depend on installation and operating conditions. A residential customer generally needs the register reading and the conversion details on the bill or from the supplier, not an identification of the meter’s internal mechanism.
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Gas installations can use different meter designs, including diaphragm, rotary, turbine, and orifice meters. The handbook says selection depends on factors such as flow range, service pressure, temperature, installation, and maintenance. These are primarily technical distinctions for commercial and utility installations, rather than a choice most household customers make.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.What to check if the bill does not match the meter
Compare the meter unit with the unit on the bill, make sure you have used the current and previous readings correctly, and check whether the bill is based on an actual or estimated reading. Then look for the heat-content or calorific-value factor and any volume correction the supplier states. Do not apply a conversion factor from another country or utility without confirming that it matches your local billing rules.
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For a UK reading or billing complaint, the government guide advises contacting the supplier first; it also identifies Citizens Advice for independent support and the Energy Ombudsman as an escalation route when the supplier cannot resolve a dispute. Elsewhere, use your utility’s local process. Do not open, alter, calibrate, or repair a utility meter; contact the supplier or utility if you suspect a meter problem.
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