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Home Energy · Converter

Gas to kWh Converter

Turn two UK gas meter readings into the kWh your supplier bills, using the calorific value from your bill and the method set out in UK regulations. Works for metric (m³) and imperial (ft³) meters.

Printed on your bill. It changes by area and period.

Standing charges are not included.

Enter both readings and the calorific value from your bill to see the kWh.

Formula

Units used = current reading − previous reading

m³ = units (metric) · or units × 2.83 (imperial, hundreds of ft³)

kWh = m³ × calorific value (MJ/m³) × 1.02264 ÷ 3.6

Cost = kWh × unit rate

CO₂e = kWh × 0.18296 kg/kWh

Worked example: 100 m³ at the GOV.UK example calorific value of 39.5 MJ/m³ is 100 × 39.5 × 1.02264 ÷ 3.6 = 1,122.1 kWh. Your bill's calorific value will usually differ slightly.

Sources: GOV.UK — Gas meter readings and bill calculation (SI 1996/439); emission factor from UK Government GHG Conversion Factors 2025 (natural gas, kWh gross CV). See the calculation methodology.

Gas kWh is fuel energy, not heat delivered. To compare it with a heat pump on the same useful heat, read the heat pump savings and payback guide. More home energy tools are in the Home Energy hub.

FAQ

How do I convert a UK gas meter reading to kWh?
Subtract the previous reading from the current one. For an imperial meter (hundreds of cubic feet) multiply by 2.83 to get cubic metres; a metric meter already reads in m³. Multiply by the calorific value on your bill (MJ/m³), then by the volume correction factor 1.02264, then divide by 3.6. This is the method set out in the Gas (Calculation of Thermal Energy) Regulations 1996 and explained in GOV.UK guidance.
Which calorific value should I use?
The one printed on your bill for that billing period. It varies by area and over time. 39.5 MJ/m³ is only the example used in the GOV.UK guidance; the same guidance says transporters keep the value within 38–41 MJ/m³.
What does the 1.02264 correction factor do?
It corrects the measured volume for temperature and pressure, because gas expands and contracts. The factor is prescribed in the regulations and applied to every domestic bill calculation.
Is my meter metric or imperial?
The unit is marked on the meter. Metric meters show "m³"; imperial meters show "ft³" and usually read in hundreds of cubic feet. Enter the readings exactly as your supplier records them.
How is the CO₂e figure calculated?
kWh × 0.18296 kg CO₂e/kWh — the UK Government 2025 conversion factor for natural gas (Scope 1, combustion only, gross calorific value basis). It excludes upstream (well-to-tank) emissions.
Can I use this for US therms or CCF?
No. This tool follows the UK billing method. US bills are calculated differently, and a therm is already an energy unit — use the therms to kWh converter for that.

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