Gas Meter Reading Calculator

How the Gas Meter Reading Calculator works

How the gas meter reading calculator converts units

Gas meters measure volume, but suppliers bill in kilowatt hours. The calculator takes the difference between your readings, converts imperial units to cubic metres by multiplying by 2.83, then applies the standard formula: cubic metres × 1.02264 × calorific value ÷ 3.6. The 1.02264 corrects for temperature and pressure.

Metric or imperial meter

A metric meter shows m³ next to the digits and usually has five numbers before a decimal point. An imperial meter shows ft³ and counts hundreds of cubic feet, usually with four digits. Read only the black or white numbers and ignore anything after the decimal point or in red.

Where to find the calorific value and prices

Your bill lists the calorific value, which changes a little from month to month, along with your unit rate and daily standing charge. Prices change with every tariff, so the calculator has none built in. Enter them in pence or cents, and the cost appears in pounds, euros or dollars.

Gas meter formula and worked examples

The formula is kWh = cubic metres × 1.02264 × calorific value ÷ 3.6, where imperial units × 2.83 = cubic metres.

Worked example 1: a metric meter goes from 4,120 to 4,215, so 95 m³ were used. At a calorific value of 39.5 that is 95 × 1.02264 × 39.5 ÷ 3.6 = 1,066 kWh. At 25p per kWh the gas costs £266.49 before the standing charge.

Worked example 2: an imperial meter goes from 2,210 to 2,244, so 34 units were used. 34 × 2.83 = 96.22 m³, which is about 1,080 kWh at the same calorific value.

The table shows how many kWh a given number of units makes on each type of meter.

kWh from meter units at a calorific value of 39.5 MJ/m³.

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