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Calculate Your Gas Bill Online

Your gas meter provides data in cubic feet or metres. Readings are taken then converted to kilowatt hours (kWh) for billing purposes. If you have your meter readings to hand, then enter your data into the gas bill calculator below to estimate your next bill.

Calculate your gas bill

Imperial Meters (ft³)

Metric Meters (m³)

Note: Imperial meters measure in hundreds of cubic feet (100 ft³). If your meter shows a usage of 1, you've actually used 100 ft³.

If you enter "1" into the imperial meter calculator and "2.83" into the metric calculator, you get the same kWh usage because 100ft³ equals 2.83m³. You should also check business gas prices to ensure the unit rate per kWh is competitive for your business.

Calculations Explained

Below is an explanation of the terms used in the calculator. Note: The gas measurement is joules, so the above calculation automatically converts to kWh by dividing by 3.6.

  • The Multiplier factor converts imperial to metric. 2.83 feet equals one metre.
  • The Conversion factor is an industry figure to account for atmospheric pressure.
  • The Calorific value adjusts for changes in the composition of gas when burned.
  • The kWh conversion 1-kilowatt hour is equivalent to 3.6 million joules.

Worked Examples

A previous meter reading of 7,380 with a current reading of 7,842 equals a difference of 482 units. Here's how you convert gas units to kWh..

Imperial Calculation

Here's how to convert cubic feet (ft3) to kWh from your gas meter reading.

482 unit used X 2.83 to convert to cubic metres X 1.02264 X 39.2 calorific value divided by 3.6 provides 15,189 kWh. At 2.84p/kWh provides an estimated bill of £431.38.

482 x 2.83 x 1.02264 x 39.2 ÷ 3.6 = 15,189 x 2.84 = £431.38.

Metric Calculation

Alternatively, convert cubic metres (m3) to kWh gas units.

482 unit used X 1.02264 X 39.2 calorific value divided by 3.6 provides 5367.27 kWh. At 2.84p/kWh provides an estimated bill of £152.43.

482 x 1.02264 x 39.2 ÷ 3.6 = 5367.27 x 2.84 = £152.43.

Calorific Values by Supplier

These values vary a little by each supplier, are governed by legislation and provided by the National Grid. The values provided are always rounded down to the next decimal place. The current values are British Gas 39.3, EDF 39.1, EON 39.2, ScottishPower 39.0 and SSE 39.6. Gas pricing differs from electricity rates per kwh due to the nature of the fuel source. Calculating electricity bills is as simply as taking a meter reading and multiplying by your unit rate.