Gas: from cubic metres to kilowatt hours

Why there are two units

The meter measures how much gas has flowed through as a volume, in cubic metres. But what you pay for is the energy in it, in kilowatt hours. Gas is not the same everywhere: depending on where it comes from, a cubic metre contains different amounts of energy. The volume also depends on pressure and temperature.

Usage from two meter readings

Your usage (Verbrauch) is the difference between two meter readings: new reading minus old reading. An example: 12,480 minus 11,480 cubic metres is 1,000 cubic metres. Only then comes the conversion into kilowatt hours.

The conversion

For this there are two factors, which your grid operator (Netzbetreiber) sets and which are on the bill:

The calorific value (Brennwert) says how much energy is in one cubic metre of gas. The conversion factor (Zustandszahl) converts the measured volume to a standard state. The formula is: kilowatt hours = cubic metres × conversion factor × calorific value.

An example with made-up values: 1,000 cubic metres × 0.95 × 10.5 gives 9,975 kilowatt hours. Your values will differ, and they can change slightly during the year.

Where the values are

On the annual bill (Jahresabrechnung), in the usage section, you find the meter readings in cubic metres, the two factors and the result in kilowatt hours. For the comparison you use the result, the annual usage in kilowatt hours.

As a rough rule of thumb, many people use about 10 kilowatt hours per cubic metre. This does not replace the value on your bill, but it helps for a first estimate.

Reading the meter correctly

On the gas meter, the digits before the decimal point count. You leave out the decimal places, often shown on a red background. It is best to take a photo of the dials and note the date. This helps with a switch or if the final bill (Schlussrechnung) does not seem right.

What the gas costs per year

The cost is usage times unit rate (Arbeitspreis) plus standing charge (Grundpreis). An example with made-up values: 15,000 kilowatt hours × 0.09 euros gives 1,350 euros, plus 150 euros standing charge, 1,500 euros a year in total. With the usage in kilowatt hours, calculations like this can be done for any tariff.

Part-year and comparison

If your bill does not cover a full year, for example after moving in, we scale the usage up. For gas we take into account that more is used in winter than in summer. We mark the scaled-up figure yellow so that you check it.

For the comparison, the unit rate in cents per kilowatt hour and the standing charge per year also count. How to read the prices on your bill is explained in the article understanding your annual bill.