Grill Gas Bottle: 5, 8 or 11 kg? The Guide

The short answer: For a permanently placed garden grill, the 11 kg propane bottle is the most sensible choice, because it delivers around 14 hours at full load on a 10 kW grill and rarely needs changing. If you have to carry the bottle, take 5 kg steel or 8 kg composite. Always store it upright outdoors, never in the cellar.

The gas bottle is the part of a gas grill that gets the least thought, until it runs empty in the middle of a barbecue evening. Yet size, gas type and the condition of the regulator and hose decide whether your grill delivers the output printed on the box at all. It comes down to a handful of figures and rules, and after that the topic is settled for years. For which appliances draw how much power, see the overview Gas grills compared.

Which size do you need: 5, 8 or 11 kg?

For a permanently placed garden grill, 11 kg is the right size. For a balcony, small appliances and anything you carry regularly, 5 kg steel or 8 kg composite is better. The reason is mundane: a full 11 kg steel bottle weighs over 20 kilograms including the bottle itself and is not something you carry up a flight of stairs casually. In return, you go to swap it far less often.

Composite bottles usually hold 8 kg and are the compromise in between. Their shell is made of plastic and glass fibre instead of steel, they are noticeably lighter than a steel bottle of the same capacity, they do not rust, and they are translucent, so you can see the fill level directly. The downside: not every exchange point stocks them, whereas the grey steel bottles are available at practically every petrol station and every DIY store that accepts gas.

One detail many people overlook: the grill itself needs room for the bottle. Measure the base cabinet before you decide on 11 kg. Many cart grills are designed for 5 or 8 kg, and the large bottle then stands beside it with the hose running across.

How long does a gas bottle last on a grill?

You can calculate this exactly: one kilogram of propane corresponds to around 12.8 kWh. Burn time at full power is therefore 12.8 times the fill amount in kilograms, divided by the grill output in kilowatts. A 10 kW grill on an 11 kg bottle comes to 12.8 times 11 divided by 10, which is around 14 hours.

Important for putting this in context: these are values at full power on all burners. Practically nobody grills like that the whole time. If you heat up and then carry on cooking indirectly at half power with two of four burners, you halve or quarter consumption. In practice an 11 kg bottle therefore lasts many households a whole season, while a heavy griller with a large appliance and a side burner swaps twice in a summer.

If you do not want to calculate, keep it simple: a second bottle as a reserve in the shed costs only a one-off deposit and spares you a ruined barbecue evening for good.

Propane or butane: which belongs on a gas grill?

Propane, without exception. Propane boils at about minus 42 °C and therefore still builds up enough pressure to supply the burners even in frost. Butane only boils at about minus 0.5 °C and gives no usable pressure below roughly 0 °C, so the flame gets weak and eventually goes out. Pure butane bottles, as found with some camping appliances and patio heaters, are unsuitable for a grill used outdoors and even more so for winter grilling.

The grey standard exchange bottles in the German trade contain propane or propane mixes and can therefore be used all year round. If you are unsure about a bottle you already have, the gas type is printed on the label and on the bottle collar.

How do you check the fill level of a gas bottle?

Weighing is the only exact method. The empty weight is stamped on the bottle collar, usually called the tare. Put the bottle on a bathroom scale, subtract the tare from the weight shown, and you have the remaining amount in kilograms. Multiplied by 12.8 kWh, you immediately know how many grilling hours are left.

The rough methods for in between:

• Pour warm water over the bottle wall. The liquid phase inside draws off heat, so the wall stays cool below the level and warm above it. The boundary you feel with your hand marks the fill level.
• Magnetic fill level indicator. It works on the same principle and changes colour at the boundary. Practical, but only an approximation.
• Look at the composite bottle. The translucent shell shows the level directly, with no aids at all.

What does not work: shaking or tapping. Liquid gas is under pressure, and the sound tells you nothing about the remaining amount.

Exchange bottle or owned bottle: what is the difference?

The exchange bottle belongs to the filler, the owned bottle belongs to you. With an exchange bottle, usually painted grey, you hand in the empty one and get a full one, and the filler looks after its condition and the recurring inspection. This is the uncomplicated route and therefore the right one for the great majority of grillers.

You buy an owned bottle once and have it refilled instead of exchanged. It has to be inspected every ten years, and you have to arrange that yourself. The advantage: you keep your own bottle, which matters mainly for composite bottles because the exchange network for them is thinner. The downside: not every collection point refills, and it is often a gas filling station or a specialist dealer rather than the petrol station around the corner.

Pressure regulator, hose and changing the bottle step by step

Gas grills for the German market usually work with a pressure regulator for 50 mbar. What always counts, though, is the rating plate of your grill, which states the required connection pressure. Camping and small appliances often run at 30 mbar. The regulators are not freely interchangeable, and the wrong pressure means either too little output or a flame that burns unevenly.

A manufacturing date is stamped on the gas hose. It should be replaced after ten years at the latest, and immediately if there are cracks, hardening, porous spots or signs of chafing. Take two minutes before every season to visually check the whole hose, including the areas at the screw connections.

How to change the bottle:

1. Switch off all burners on the grill and close the valve of the empty bottle completely.
2. Unscrew the regulator. The union nut on propane bottles has a left-hand thread, so it opens clockwise.
3. Set up the full bottle, remove the protective cap and check the sealing ring in the regulator connection. If it is missing or cracked, it will not work.
4. Screw on the regulator hand-tight, turning anticlockwise again. No tools are needed for this, and they usually do harm.
5. Open the valve slowly, keeping the grill switched off.
6. Leak test: spray all connections with leak-detection spray or soapy water. If bubbles form, that spot is leaking. Then close the valve immediately, reseat the connection and test again. Never look for leaks with an open flame.
7. Only when nothing bubbles, open the valve fully and light the grill as usual.

After grilling you proceed in reverse: close the bottle valve first, let the burners run a little longer until the flame goes out by itself, then turn off the controls on the grill. That way no gas is left standing in the hose.

Storing and transporting safely

The rules are short, and none of them is negotiable.

• Always store and transport upright, never lying down. If the bottle lies on its side, liquid phase can get into the regulator.
• Never below ground level. Propane is heavier than air and collects at floor level. Cellars and similar rooms are not permitted for storage.
• Not in living spaces and not in strong sun. A ventilated, shaded spot outdoors is ideal.
• Garage: The rules differ by German federal state, and the relevant state garage regulation is what counts. If in doubt, check there.
• In the car: upright and secured against tipping, valve closed, protective cap on, vehicle ventilated. The bottle does not belong in a heated-up car and should not stay in it longer than necessary.

One phenomenon that regularly leads to wrong diagnoses: if an almost empty or heavily chilled bottle frosts over on the outside and grill output collapses, that is not a fault in the grill but evaporative cooling. The vaporising of the liquid gas draws heat from the bottle, and the pressure drops. A larger bottle with more surface area or a warmer location helps. Never warm the bottle with an open flame, hot water or a fan heater. If your grill does not reach temperature for other reasons, take a look at the guide Gas grill not getting hot, which lists the most common causes in order.

Which bottle suits you?

Balcony and occasional grillers: 5 kg steel. It is light enough for stairs, fits under small cart grills and delivers around 9 hours at full load on a 7 kW appliance, which covers a good number of barbecue evenings. If you carry it often and have the space, the 8 kg composite bottle is the more pleasant option.

Family with a mid-sized grill: 8 kg composite or 11 kg steel. With three to four burners at around 10 kW, 8 kg gives you about 10 hours at full load, and 11 kg about 14. If the grill stands permanently in the garden and you do not keep moving it, there is little against the large steel bottle.

Heavy grillers and large grills: 11 kg steel, and two of them. From six burners plus a side burner, meaning 14 kW and more, the full-load reserve shrinks to around 10 hours. A full spare bottle in the shed is not over-caution here, but the difference between a finished roast and a cold grill.

If you are still choosing the appliance itself and want to know which burner output suits your usage profile, the Grill Finder will help. The bottle size then follows almost by itself.