Gas bottle level indicator: which method fits the bottle

Updated: 22 October 2026

You are at the locker or the barbecue, the cylinder is closed, and you cannot see the liquid. A gas bottle level indicator is a way to estimate what is left in a propane or butane exchange bottle.

You are at the locker or the barbecue, the cylinder is closed, and you cannot see the liquid. A gas bottle level indicator is a way to estimate what is left in a propane or butane exchange bottle. The useful choice is the method that matches the wall: a colour step, a yes-or-no light, a kilogram figure, or a gauge already fitted to the bottle. On the gas bottle level indicator comparison the magnetic strips in this amazon.co.uk set sit around £3.95 to £9.99, and the only ultrasonic meter is the Truma LevelCheck at £74.99. Nothing here was laboratory-tested. If you buy through our amazon.co.uk links, we may earn a commission at no extra cost to you.

Our top picks

Badge	Product	Method	Wall	Size limit	Note	Price	Offer
Best overall	Truma Truma LevelCheck	Handheld ultrasonic probe	Steel and aluminium	200–350 mm diameter	9.2	about £74.99	View offer
Best value	Volnamal Volnamal magnetic strip	Magnetic temperature strip	Steel not named	Lower half of the cylinder	6.6	about £3.99	View offer
Alternative	Cowiny Cowiny 3-pack magnetic strips	Magnetic liquid-crystal strip	Suitable steel; check the magnet	Lower outside area	4.3	about £6.49	View offer

Best overall

Truma Truma LevelCheck

9.2/10about £74.99

View offer

Best value

Volnamal Volnamal magnetic strip

6.6/10about £3.99

View offer

Alternative

Cowiny Cowiny 3-pack magnetic strips

4.3/10about £6.49

View offer

On this page

1.What you are trying to read
2.Start with the bottle wall
3.Strip, probe, or scales
4.What to ignore on a listing

What you are trying to read

A magnetic strip does not weigh the gas. It shows a temperature step on the wall. While propane or butane evaporates, the liquid cools the steel, and the bars change colour along that boundary. Homestead Caravans describes a 114 × 50 mm card that works only while gas is drawn, near the bottom, as a warning rather than a laboratory reading. In this set the probe is the Truma LevelCheck. A green LED means liquid at the point you are holding, and a red LED means none, or a contact the meter cannot trust. That is one height, not a kilogram. Scales answer in mass. Flogas tells you to weigh the cylinder and subtract the tare on the collar disc.

Start with the bottle wall

Colour Changing, a UK seller of a £3.95 card, states steel only. Several amazon.co.uk listings in this set never say steel. Cowiny and Rivvra do. Cowiny tells you to check that the surface attracts the magnet. Rivvra names compatible steel bottles. The LevelCheck states both steel and aluminium, on cylinders from 200 mm to 350 mm diameter. A 47 kg cylinder is wider than the Truma window on published UK dimension tables, so that probe's stated limit leaves it out even when the wall is steel. The listing also says the LevelCheck is not for refillable tank bottles. Campingaz-type butane sits outside the manufacturer's description as well.

Testsieger

Truma Truma LevelCheck

9.2/10about £74.99

View offer

Strip, probe, or scales

Strips in this set need evaporation, so the appliance has to be drawing gas. One Cowiny reviewer, in a sample of two, ran three barbecue burners for ten minutes at 15 °C and saw no shift, then checked with an infrared thermometer that the wall had not cooled. The Truma listing bullets do not require the gas to be flowing. The manufacturer page adds a 9 V battery and about 100 g. The amazon.co.uk listing prints 200 g and a power-source field that says gas powered. When the trip depends on a number, weigh the cylinder against the tare disc. Sticking a card or a probe on the outside is not gas work under the Gas Safety (Installation and Use) Regulations 1998. A smell that remains belongs to a Gas Safe engineer qualified for LPG.

What to ignore on a listing

Battery-free cards in this set sometimes carry a field that sounds like a laboratory tolerance. YG-YUNCHUANG's accuracy line says the level is within about 10 percent of remaining capacity. Linswell's field says ±2 °C. Ruiunchu carries percent and digital fields the bullets never explain. None of those lines is a weighed test, and none of those three listings has a review file in this set. A temperature window such as -10 °C to 120 °C describes when the crystals can react. It does not convert a colour bar into kilograms. If you already own a card, the sequence sits on how to use a gas bottle level indicator. The price decision between a card and the LevelCheck is on magnetic versus ultrasonic. Who each of the twelve listings is for sits on the best gas bottle level indicator page.

Common questions

Will a magnet work on my bottle?

A magnet works on a steel wall that attracts it. Colour Changing states steel only for its card. Aluminium needs a probe such as the Truma LevelCheck, which states steel and aluminium from 200 mm to 350 mm, or a set of scales. A composite bottle such as Flogas Gaslight is see-through. You look at the liquid. A magnet on that shell is the wrong tool.

Can I read a strip with the appliance off?

The colour boundary needs evaporation, so gas has to be leaving the bottle. A card read with the appliance off can look blank, or it can look fully coloured because the wall is simply at room temperature. The Truma listing does not require flow for the probe. Keep that instruction with the probe, and keep the strip's gas-on instruction with the strip.

When is a probe worth about £75?

The LevelCheck at £74.99 is the one to consider when the wall is aluminium, when you want to test several bottles with one tool, and when a yes-or-no at one height is enough. It is a weak buy when you need kilograms, when the cylinder is wider than 350 mm, or when the bottle is plastic, a refillable tank, or a Campingaz-type butane cylinder. The manufacturer excludes those last three.

Is a regulator gauge a level reading?

A regulator gauge reads inlet pressure. Pressure stays high while liquid remains in the cylinder and drops when that liquid has gone, so the needle can sit on full for most of the bottle. It will not tell you that you are halfway through a 13 kg exchange cylinder. Use it as a something-is-still-there light near the end, and use scales when you need the amount.

Should I weigh the bottle instead?

Weigh it when the answer has to be a mass. Subtract the tare on the disc from the reading on the scales. The worked example Flogas publishes is a 13 kg exchange bottle: the number on the scales minus the disc is the gas, and the steel stays in the tare. For a trip you cannot interrupt, the scales are the check that matches the supplier's own method.

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