11-kg-Gasflasche im Wohnmobil: Wie lange reicht sie wirklich? Mit kostenlosem Verbrauchsrechner!

In summer, an 11 kg gas bottle feels like it lasts forever. In autumn and winter, things can look very different. Depending on whether and how much you heat your motorhome or caravan, and how much hot water you need, your consumption can range anywhere from 2 to 14 days.

That's obviously too vague a range to plan your trip around, so in this guide we'll break down how much gas your heater, fridge, stove, and boiler actually use, how to calculate your own consumption properly, and which gas works best in winter.

What your appliances actually use

Every gas appliance has a consumption rate per hour, listed in the spec sheet, usually ingrams per hour (g/h).

A few classic heaters as examples:

• the Truma Combi 4 uses up to 335 g/h at maximum

• the larger Combi 6 uses up to 460 to 480 g/h, depending on the generation

• the Trumatic S 3004 maxes out at 280 g/h

• the VarioHeat comfort uses around 290 g/h.

The absorber fridge is a real penny-pincher by comparison: just 14 to 18 g/h. The stove uses up to 160 g/h on the large burner, around 70 g/h on the small one.

The Truma B10 boiler (now called the Boiler Gas BG 10) uses 120 g/h and takes about 31 minutes in pure gas mode to heat 10 liters of water from 15°C to 70°C. The oven and gas grill sit at 100 to 150 g/h and 150 to 250 g/h respectively.

But the maximum value alone doesn't tell the whole story. A heater rarely runs at full power the whole time – the thermostat only switches the burner on for part of the time.

Thisduty cycle is usually 20 to 40 percent in autumn, and 50 to 70 percent during frost. Stoves, boilers, and grills, on the other hand, run continuously while in use – a 100 percent duty cycle.

Autumn calculation example: nearly a week on one bottle

A typical autumn day with heating, fridge, cooking, and boiler use looks something like this:

• Heating (12 hours at 30 percent duty cycle): 1,206 grams per day.

• Fridge (24 hours continuous): 360 grams.

• Stove (30 minutes of use): 75 grams.

• Boiler heat-up: 62 grams.

That adds up to 1,703 grams per day, or 1.7 kilograms – an energy equivalent of 21.9 kWh.

A full 11 kg bottle lasts 6.5 days under these conditions.

Winter calculation example: a week becomes two days

At -5°C, the math looks completely different.

• Heating (24 hours at 50 percent duty cycle): 5,760 grams

• Fridge: still 360 grams

• Stove and boiler are now used more often: 113 + 124 grams

That totals 6,357 grams per day, or 6.36 kilograms, equivalent to 81.8 kWh of energy. The 11 kg bottle is empty after just 1.7 days.

This is deliberately a worst-case scenario: the calculation assumes the heater runs at full blast half the time, but in practice a modern unit usually modulates down to a lower setting. Even so, the bottle is empty after a good five days – and much sooner in strong wind or with poor insulation.

Calculate your own consumption in four steps

The logic behind it is simple and works for any vehicle:

Consumption per appliance in grams per day = consumption in g/h × operating hours × duty cycle.

If you know your appliance's output in kW instead of its gas consumption, you can convert it:

g/h = kW ÷ (12.87 kWh/kg × efficiency) × 1,000.

A 4 kW heater with 93 percent efficiency works out to 334 g/h – almost exactly the spec sheet value for the Truma Combi 4.

In practice, that means:List every gas appliance in your vehicle, note its hourly consumption, add your estimated daily usage time and duty cycle, then multiply and add it all up.

Our calculator below does the math for you: just select your heater type, fridge, stove, and boiler, enter your bottle size and trip length – and you'll instantly see how long the bottle will last and how many you need for the trip.

The most common calculation mistake: assuming a 100 percent duty cycle for the heater. That usually overestimates consumption by double, since modulating heaters often run on a lower setting.

Propane or butane – why it's not just a minor detail in winter

The grey exchange bottles sold in Germany must contain at least 95% propane according to DIN standards. Why does that matter? The difference to butane isn't about energy content, it's about cold tolerance:

Butane boils at -0.5 °C and can no longer vaporize in freezing temperatures – the bottle is still heavy, but no more gas comes out.

Propane, on the other hand, stays usable down to about -42 °C. The examples in this article also work with its calorific value of 12.87 kWh/kg.

The mix matters with refillable gas tanks filled at autogas stations: in summer you usually get 40 percent propane and 60 percent butane, while in winter there's "winter gas" with 60 to 95 percent propane.

If you're wintering in southern Spain or southern Italy and barely have to worry about frost, the local mix is usually fine. But if you're heading towards Scandinavia or into the snow, you should deliberately fill your tank with winter gas beforehand – otherwise you'll end up with a useless butane sludge sitting in the bottle.

More on this, including gas bottles abroad, in the article Propane or butane? Which gas works best for what.

The biggest gas guzzlers of the cold season

During heating season, the ranking of consumers shifts noticeably. According to our sample calculation, the heater accounts for around 71 percent of total daily consumption in autumn, and its share climbs even higher in winter due to longer run times.

The main gas consumers in winter, ranked by share:

• Heater: by far the biggest consumer, 150 to 500 g/h depending on the unit and outside temperature

• Hot water/boiler: around 120 g/h during the roughly 30-minute heat-up phase

• Cooking: 50 to 160 g/h, but usually only for short periods

• Fridge: the smallest item at 14 to 20 g/h, but it often runs 24 hours a day

If you keep this order in mind, you'll know where it actually pays to save: not on the fridge, but on the heating level.

Plan for a reserve instead of freezing afterwards

In practice: the consumption figures from the calculation are approximate maximum values meant as a rough guide to help you plan a bottle swap in time. Actual consumption can be higher, for example if the heater runs longer than expected or the grill gets used more often. That's why it's worth checking the fill level regularly, especially in winter, since outside temperature and usage patterns vary from day to day.

For longer winter trips, a second full gas bottle is practically mandatory, not just as an emergency reserve but as a fixed part of your planning. If you're often out in the depths of winter, consider an automatic dual-bottle system that switches over on its own once a bottle runs empty, or use larger 33 kg bottles in the exterior locker, provided the campsite allows it.