Converting gas m³ to kWh: the Belgian converter and the method behind the figure

Your meter shows cubic metres, your bill talks in kilowatt-hours, and the gap between the two comes down to a single number: the conversion coefficient. In Belgium, count on roughly 11.6 kWh per m³ of high-calorific gas. The converter below works in both directions, and the rest of this article explains where that coefficient comes from.

How do you convert gas m³ into kWh?

Multiply your volume in cubic metres by the conversion coefficient printed on your bill.

The formula fits on one line: m³ × conversion coefficient = kWh. Everything else is just the question of which coefficient to use. Your meter measures a volume — it is a flow meter, not a calorimeter. Your supplier sells energy, because two cubic metres of gas with different compositions do not release the same amount of heat when burned. The conversion coefficient bridges the two.

In Belgium, the CREG publishes two reference values around which real coefficients fluctuate only slightly: 11.6 kWh/m³ for high-calorific gas (H), and 10.3 kWh/m³ for low-calorific gas (L). The regulator gives its own worked example: 1,500 m³ × 11.6 = 17,400 kWh.

Where does the conversion coefficient actually come from?

From the gross calorific value of the gas actually delivered on your network, month by month.

The gross calorific value (GCV) is the amount of heat released by the complete combustion of a given quantity of natural gas. It depends on the composition of the gas: the proportions of methane, ethane, nitrogen and carbon dioxide. And that composition is not constant, because the gas consumed in Belgium comes from several sources and enters through several points.

The CREG therefore states that the GCV varies from month to month and depends on the aggregated receiving station (SRA) you are connected to. Two neighbouring Walloon municipalities can depend on two different SRAs and be charged slightly different coefficients in the same month.

The orders of magnitude published by the network operators converge:

• ORES reports, for its network, a GCV of between 10.81 and 12.79 kWh/m³(n).
• The CWaPE gives a general range of 10 to 12 kWh per m³, and notes that the annual conversion rate fluctuates with the calorific value of the gas consumed.
• Sibelga publishes the GCV values per aggregated receiving station on its Brussels network as open data.

What is the difference between high-calorific (H) and low-calorific (L) gas in Belgium?

Low-calorific gas releases roughly 15% less energy per cubic metre — but it has all but disappeared from the country.

Belgium was long supplied by two separate networks: low-calorific gas (L) from the Dutch Groningen field, and high-calorific gas (H) imported from Norway, the United Kingdom and by LNG carrier. After the Dutch authorities decided to end their exports at the end of 2024, Belgium converted all of its networks to H gas. The regional regulators document the operation, spread over several years — see Brugel on the conversion of the gas networks and the CWaPE on the conversion phase opened on 1 June 2024. ORES confirms it now distributes high-calorific gas only, low-calorific gas having still circulated in some areas until 1 September 2024.

The practical consequence for conversion: if you are calculating today, use the high-calorific coefficient. The low-calorific coefficient remains useful for reading old bills, or for comparing with a home outside Belgium.

The effect on the result is far from trivial. For 1,250 m³ read on the meter:

• with high-calorific gas: 1,250 × 11.6 = 14,500 kWh;
• with low-calorific gas: 1,250 × 10.3 = 12,875 kWh.

That is 1,625 kWh of difference, purely because of the coefficient. At €0.11/kWh all-in, that comes to nearly €180 on an annual bill.

What do 1,500 m³ of gas amount to in kWh and in euros? The worked example

1,500 m³ of high-calorific gas comes to 17,400 kWh, or roughly €1,914 a year all-in.

Let us take, step by step, the case of a Walloon household that reads 1,500 m³ on its meter between two annual statements, on a network supplied with high-calorific gas.

1. Volume consumed: closing index minus opening index = 1,500 m³.
2. Conversion coefficient: 11.6 kWh/m³, the CREG reference value for H gas. On a real bill it would look more like 11.6293.
3. Energy: 1,500 × 11.6 = 17,400 kWh.
4. Cost: 17,400 × €0.11 = €1,914 a year, using an all-in price incl. VAT of €0.11/kWh, an order of magnitude observed on the Belgian market in August 2026.

This household therefore sits just above the CREG standard residential profile D3a, set at 17,000 kWh a year — the benchmark regulators and comparison sites use to line up price grids. To place that figure against your own housing type, our article on average gas consumption in Belgium gives the ranges for apartments, terraced houses and detached houses.

Watch what the price you use actually covers. The €0.11/kWh is an all-in price: energy component, transport costs, distribution costs, taxes and VAT. The energy component alone, the one shown in supplier price grids, was closer to €0.05–0.07/kWh over the same period. Confusing the two changes the result by a factor of two — it is the most common mistake, and the converter above lets you switch explicitly between the two modes.

How many kWh are there in 1 m³ of gas? The reference table

Here are the most requested correspondences, calculated with the two CREG reference coefficients.

These amounts are constant-price estimates, excluding the supplier's fixed annual standing charge. They are there to place an order of magnitude, not to replace a settlement.

How do you convert gas kWh back into m³?

Divide your kWh by the conversion coefficient.

This is the reverse calculation, and it is just as useful: your supplier bills in kWh, but the index you read on the dial is in cubic metres. To check whether an advance payment estimate holds up, you have to go back to volume.

The formula: kWh ÷ conversion coefficient = m³. For the reference consumption of 17,000 kWh with high-calorific gas, that gives 17,000 ÷ 11.6 = 1,465.5 m³. In other words, if your meter turns by about 1,465 m³ over a year, you are exactly on the Belgian standard profile.

The meter counts cubic metres. The supplier sells kilowatt-hours. The conversion coefficient is the only place the two meet — and it is never the same two months running.

What are the limits of this converter?

It gives an accurate order of magnitude; it does not reconstruct a bill.

Three things it does not do, and that it is honest to state:

• It does not apply volume allocation. The CREG points out that checking a coefficient yourself means spreading consumption across the year according to the consumption profiles approved by the VREG, the CWaPE or Brugel. A household does not consume linearly: it heats in January, not in July, and the monthly weighting changes the average coefficient.
• It does not include the fixed standing charge. The cost shown is purely energy × unit price. Yet almost every Belgian contract adds an annual standing charge, which weighs more heavily the lower your consumption.
• It does not distinguish between regions. Network costs differ between Wallonia, Brussels and Flanders. A single all-in price is a deliberate simplification.

This is neither a quote, nor an official calculation, nor personalised advice. For the value that counts, only your bill and your network operator matter — ORES or RESA in Wallonia, Sibelga in Brussels, Fluvius in Flanders.

What mistakes do people most often make when converting their m³?

Four of them, and they all look alike: the right calculation with the wrong number.

Confusing the all-in price with the energy component. The costliest interpretation error. A price of €0.06/kWh shown in a tariff grid is not what you end up paying.

Reusing a French coefficient. Coefficients published by French distributors are based on other networks and other delivery altitudes. The order of magnitude is close, but the value does not apply to your Belgian bill.

Still using the low-calorific coefficient. Understandable for anyone who has read a page written before 2024 — but L gas is no longer distributed in Belgium. You would underestimate your consumption by roughly 11%.

Extrapolating a short period across a full year. Multiplying a winter quarter's consumption by four gives an absurd result. Heating destroys any proportionality.

What next?

Once you have your kWh, the real lever is no longer the calculation but the contract. Conversion gives you a number; your supplier's price grid decides what it costs you. Enter your annual consumption in kWh into our energy offer comparison tool and set it against the ranking of energy suppliers, which works on total annual cost rather than headline price per kWh. To understand what the various lines on your statement cover, our guide to understanding your energy bill goes through each item in order.

Sources — CREG, "Conversion du m³ de gaz en kWh" (accessed 18 August 2026); ORES, "Le pouvoir calorifique du gaz", GCV of 10.81 to 12.79 kWh/m³(n) and end of low-calorific gas on 1 September 2024 (accessed 18 August 2026); CWaPE, "À combien de kWh correspond 1 m³ de gaz ?", page updated 11 December 2025 (accessed 18 August 2026); Brugel, "La conversion des réseaux de gaz" and CWaPE, "Passage du gaz pauvre au gaz riche: phase de conversion à partir du 01/06/2024" (accessed 18 August 2026); Sibelga, open data "Pouvoir calorifique supérieur du gaz" per SRA (accessed 18 August 2026). Gas price per kWh: orders of magnitude on the Belgian market recorded in August 2026, to be re-checked before any decision, since variable offers are reindexed monthly.