Fixed or variable gas: which formula to choose
A fixed gas contract locks your energy price for the whole term. A variable one follows a published index and moves with the market. The choice is not about finding the cheaper option in advance — nobody can — but about deciding whether you are buying a price or buying predictability.
| Provider | Plan | Price | Key points | View plan |
|---|---|---|---|---|
| Our partners — featured offers | ||||
 MegaPartner |
Prepaid Flex | 6.04 c€/kWh+ €40 annual standing charge |
| View plan |
 Octa+Partner |
Flux | 6.14 c€/kWh+ €70 annual standing charge |
| View plan |
 BoltPartner |
Plenty Variable Online | 7.24 c€/kWh+ €11.88 annual standing charge |
| View plan |
 ElegantPartner |
Elegant Gaz | On request |
| View plan |
 Frank EnergiePartner |
Frank Gas | On request |
| View plan |
| End of our partners’ offers — the plans below are part of no commercial partnership | ||||
 DATS 24 |
Gaz Naturel Variable | 4.64 c€/kWh+ €38.50 annual standing charge |
| View plan |
 EnergyVision |
Gaz bon marché 1 an fixe | 5.80 c€/kWh+ €75 annual standing charge |
| View plan |
 Ecofix |
Flexy Online | 6.17 c€/kWh+ €10 annual standing charge |
| View plan |
 TotalEnergies |
myEssential Variable | 6.47 c€/kWh+ €35 annual standing charge |
| View plan |
 Luminus |
BasicFlex Gaz | 6.99 c€/kWh+ €20 annual standing charge |
| View plan |
 Eneco |
Gaz Naturel Flex | 7.02 c€/kWh+ €65 annual standing charge |
| View plan |
 Engie |
Basic Variable | 7.09 c€/kWh+ €20 annual standing charge |
| View plan |
 Trevion |
Trevion Gaz | On request |
| View plan |
Prices and features surveyed on September 3, 2026. They may have changed since. Always check the offer on the provider’s website before signing up.
What each formula actually does
A fixed price is set on the day you sign and does not move for the term, typically one to three years. Your winter bill is knowable in advance, which is the entire point.
A variable price follows a published index, revised monthly or quarterly. It falls when wholesale gas falls and rises when it rises, and your supplier publishes the index it uses in the tariff card.
A dynamic price follows the hourly market. It suits consumption you can move — a dishwasher, a car charger — and gas is the one energy you essentially cannot move, since you heat when the house is cold.
What you are paying for with a fixed price
The supplier who sells you a fixed price has to buy that gas forward, and hedging costs money. That cost is embedded in the price you are quoted, which is why fixed contracts sit above variable ones at the moment of signing almost every time.
The question is therefore not whether the fixed price is higher today — it is — but whether the market will rise enough during the term to make up the gap. That is a bet on gas prices, and it is not a bet a household is better placed to win than a trading desk.
The cost of leaving before the end
Belgian residential energy contracts can be terminated with one month's notice, and no exit fee may be charged to a household — that protection is written into federal consumer law and applies to fixed contracts too.
What you lose by leaving a fixed contract early is the price itself, not a penalty. If the market has fallen far enough, leaving is simply the right move, and nothing in the contract prevents it.
Our verdict
Over long periods, variable contracts have generally cost less than fixed ones in Belgium, because the premium charged for certainty is real and permanent. Fixed pricing buys you a budget, not a saving. If an unpredictable winter bill would genuinely put your household under strain, that premium is worth paying; otherwise it rarely is.
Frequently asked questions
Is a fixed gas price safer?
It makes your bill predictable, which is a different thing from cheaper. You pay a premium for that predictability at signing, and if the market falls during the term you keep paying the old price. Fixed pricing protects a budget; it does not protect a wallet.
How often does a variable gas price change?
Monthly or quarterly, depending on the contract. The tariff card names the index used and the revision frequency, and both are worth reading: two contracts described as variable can follow different indices and move at different speeds.
Can I leave a fixed gas contract early?
Yes. A Belgian household may end an energy contract with one month's notice, and no exit fee can be charged, whatever the contract's stated term. What you lose is the fixed price you had secured, not money paid as a penalty.
Does a dynamic tariff make sense for gas?
Rarely. A dynamic price rewards consumption you can shift to cheaper hours, and heating is not shiftable — you heat when the house is cold. Dynamic pricing pays off on electricity, where a car charger or a heat pump can be scheduled, far more than on gas.