Elgas LPG Gas Blog

LPG (propane) Gas Unit Conversions: Gas in kg, Litres, MJ, kWh & m³

Also Propane Gas Unit Conversion in Pounds, Gallons, BTU, Therms & ft³

Where LPG is propane, 1kg of LPG has a volume of 1.96 litres. Conversely, 1 litre of LPG weighs 0.51kg.

LPG Specific Gravity - Density: Unlike water, 1kg of LPG does NOT equal 1 litre of LPG. This is because the density or specific gravity of LPG is less than water.

Gas unit conversion is the comparison of one gas unit measurement with another. Having a given quantity of one gas unit, you convert it to an equivalent amount in another gas unit, with a gas unit conversion formula, table or chart.

We are frequently asked about the various LPG - propane - gas unit conversion (LP gas unit conversion) values. 

The first table shown below covers most of the common gas unit conversion measures and gas bottle-cylinder sizes for Australia, including kg, litres, MJ, kWh & m³ (e.g. LPG gas unit conversion of kg to litres is 1kg = 1.96L).

People ask the questions in many ways and the simplest way to answer most of them is with an LPG Gas Unit Conversion Table (or two). 

Gas Unit Conversion

One kilojoule = 0.9478 BTU, when converting from metric (joules) to Imperial units (British Thermal Units) of measure. Metric pressure units are Pascals vs PSI. One kPa (kilopascal) = one thousand pascals.

Convert kg to Litres LPG - LPG Conversion kg to Litres - How Do You Convert LPG kg to L - Convert kg to Litres LPG

Unlike water, 1kg of LPG does NOT equal 1L of LPG. This is because the density or specific gravity of LPG is less than water. In Australia, where LPG is propane, 1kg of LPG has a volume of 1.96L. Conversely, 1L of LPG weighs 0.51kg.

How many litres are in 1 kg of LPG? There are 1.96 litres in 1 kg LPG. In Australia and US, LPG is >95% propane and weighs 0.51 kg per litre, so 1 kg = 1.96 litres.

To convert kg to litres LPG: LPG conversion kg to litres is 1 kg = 1.96 litres.

So, 1 kg LPG gas is 1.96 liters of LPG (convert LPG kg to litres).

For example, there are 29.4L litres of LPG in a 15kg cylinder. There are 35.3L litres of LPG in a 18kg cylinder.

LPG Specific Gravity - Density

Unlike water, 1kg of LPG does NOT equal 1L of LPG. This is because the density or specific gravity of LPG is less than water. In Australia, where LPG is propane, 1kg of LPG has a volume of 1.96L. Conversely, 1L of LPG weighs 0.51kg.

Convert Litre to kg LPG - Litre to kg Conversion for Gas

In Australia and the US, LPG is over 95% pure propane and is 1.96 litres to kg so, 1 litre = 0.51 kg.

For litre to kg conversion for gas: LPG litre to kg is 1 litre LPG = 0.51kg LPG (convert litre to kg LPG)

LPG conversion kg to litres (convert kg to litres LPG) and LPG litre (liter) to kg are the two most common LPG gas unit conversions.

It is important to note that water and LPG (propane) have different conversion formulas because they have different density.

Water Litre to kg: 1 Litre = 0.999975 kg, so for all practical purposes 1 L = 1 kg

Water kg to Litre: 1 kg = 1 litre

Example: LPG Gas 14.2 kg Equals How Many Liters with 75% Butane

For LPG (propane) 1 kg = 1.96 L. Therefore, 14.2 kg = 27.832 L.

For LPG (butane) 1 kg = 1.724 L. Therefore, 14.2 kg = 24.48 L

LPG gas 14.2 kg equals how many litres with 75% Butane?

To calculate volume, in litres, takes some simple arithmetic. With a 75:25 butane:propane mix, 1kg = 1.783 L.

Therefore. 14.2 kg = 25.34 L, with a 75:25 butane:propane mix.

LPG Gas Unit Conversion Formulas (Metric):

  • Convert LPG kg to litres: 1 kg = 1.96 L of LPG

  • Convert LPG litres to kg: 1 L = 0.51 kg of LPG

  • Convert LPG kg to m³: 1 kg = 0.546 m³ of LPG (this is an LPG liquid to LPG gas conversion)

  • Convert LPG cubic metre to kg: 1 cubic metre = 1.8315 kg of LPG (this is an LPG gas to LPG liquid conversion)

  • Convert LPG litres to m³: 1 L = 0.27 m³ of LPG (this is an LPG liquid to LPG gas conversion)

  • Convert LPG m³ to litres: 1 m³ = 3.70 L of LPG (this is an LPG gas to LPG liquid conversion)

  • Convert LPG MJ to kWh: 1 MJ = 0.278 kWh of energy from LPG

  • Convert LPG kWh to MJ: 1 kWh = 3.6 MJ of energy from LPG

  • Convert LPG litres to MJ: 1 L = 25 MJ of energy from LPG

  • Convert LPG MJ to litres:  1MJ = 0.042 L of LPG

  • Convert LPG kg to MJ: 1 kg = 49 MJ of energy from LPG

  • Convert LPG MJ to kg: 1 MJ = 0.02 kg of LPG

  • Convert LPG litres to kWh: 1 L = 6.9 kWh of energy from LPG

  • Convert LPG kWh to litres: 1 kWh = 0.145 L of LPG

  • Convert LPG kg to kWh: 1 kg = 13.6 kWh of energy from LPG

  • Convert LPG kWh to kg: 1 kWh = 0.074 kg of LPG

  • Convert LPG litres to BTU: 1 L = 23,700 BTU of energy from LPG

  • Convert LPG kg to BTU: 1 kg = 46,452 BTU of energy from LPG

The second table covers most of the units of measure and gas bottle sizes for the USA including Pounds, Gallons, BTU, Therms & ft³.
You can convert all combinations of Pounds, Gallons, BTU, Therms & ft³.

Gas Unit Conversion Background Information

LPG Specific Gravity - Density

LPG (propane) kg to litres: 1kg = 1.96L. Unlike water, 1 kg of LPG does NOT equal 1 L of LPG.  This is because the density or specific gravity of LPG is less than water. In Australia, where LPG is propane, 1 kg of LPG has a volume of 1.96 L. (1 kg LPG gas has 1.96 liters)

Conversely, 1 L of LPG weighs 0.51 kg.

LPG Gas Consumption in Megajoules

Megajoules per Hour (MJ/hr) ratings on appliances actually indicate the gas consumption of the appliance, not the output.  
It is often expressed as just MJ. In the USA, they use BTU as the unit of measure.

LPG Litres to kWh - LPG kg to kWh

LPG litres to kWh: LPG 1L = 6.9 kWh of energy. To convert LPG kWh to litres: 1 kWh = 0.145 L of LPG

To convert LPG kg to kWh: 1 kg = 13.6 kWh of energy from LPG. To convert LPG kWh to kg: 1 kWh = 0.074 kg of LPG

Appliance Output in kWh

Kilowatt Hour (kWh) is how appliance output is measured. 3.6 MJ of input equals 1kWh of output at 100% efficiency. 
However, no gas appliance is 100% efficient. 
That is why we have Star Ratings, so we can compare relative efficiency between models. 
Appliance output is often expressed as just kW.

BTU to MJ Gas Unit Conversion

LPG energy content is expressed in BTU and MJ - Megajoules.

BTU, or British Thermal Unit, is another older measure of heat output based on the Imperial System.

As previously mentioned, BTU is used in the USA instead of MJ. 

One BTU is the energy required to raise the temperature of 1 pound of liquid water by 1°F, at sea level.  

1MJ equals 948 BTU, so to get an equivalent number of Megajoules, just divide the BTU rating by 948. 

LPG BTU per Litre - Propane BTU per Litre - LPG Energy Content Gas Unit Conversion

LPG - Propane BTU per litre: 1 litre = 23,700 BTU per litre. Propane BTU per liter combines an old imperial energy measurement - BTU - with a metric volume measurement - litre.

LPG - propane energy content is expressed in BTU per litre.

This is based on 1MJ equalling 948 BTU, so to get an equivalent number of BTU, just multiply the MJ rating by 948

So, as 1L = 25 MJ then 25 MJ x 948 = 23,700 BTU per litre

LPG BTU per KG - LPG Energy Content Gas Unit Conversion

LPG BTU per kg is 46,452 BTU in 1 kg of LPG. LPG BTU per kg is LPG energy content based on weight.

LPG energy content gas unit conversion is expressed in BTU per kg. LPG - Propane BTU per kg = 46,452 BTU per kg

Since 1kg of LPG = 1.96 L, then based on the above 1.96 x 23,700 BTU/L = 46,452 BTU. So, 1kg = 46,452 BTU per kg

Combining metric and imperial measures is not typical but it can be easily calculated.

LPG Liquid to Gas Volume Expansion Gas Unit Conversion

LPG (propane) expands about 270 times in volume when it goes from liquid to gas. 
So, 1L of liquid LPG equals 270L of gaseous LPG. 
As there are 1000L in a cubic metre (m³), 1 L of liquid LPG expands to 0.27 m³.

LPG Cubic Metre to kg ⇔ LPG kg to Cubic Metre (m³) Gas Unit Conversion

LPG one cubic metre = 1.8315 kg (1 m³ = 1.8315 kg). Whilst propane is 1m³ = 1.8315 kg, butane is 1m³ = 2.4486 kg. Propane and butane have different densities so the lpg cubic meter to kg value is different.

When comparing LPG cubic metre to kg (m3 to kg) you are comparing LPG volume in its gaseous state (cubic metre) to the mass of LPG liquid (kg).

One cubic metre of LPG weighs 1.8315 kg (1m³ = 1.89 kg), which is an LPG gas to LPG liquid conversion.

The reciprocal is 1 Kg of LPG would be 0.53 cubic metres (1kg = 0.546m³), which is an LPG liquid to LPG gas conversion.

The values above assume the LPG is propane.

To convert LPG cubic metre to kg you simply use the propane-LPG cubic metre to kg gas unit conversion formula: LPG cubic metre (m³) = 1.8315 kg.

The more detailed explanation for LPG cubic metre to kg is one LPG cubic metre (m³) of gas equals to 1.8315 kg of liquid LPG (propane) at 25 °C (77 °F). LPG cubic metre to kg (m3 to kg) varies with temperature.

The same is true of LPG kg to m³ conversion.

LPG kg to cubic metre is: 1kg =  0.546 m3 (propane)

For butane LPG kg to cubic metre: 1kg = 0.4084 m3 at 25 °C (77 °F)

For butane LPG cubic metre to kg is: 1m3 = 2.4486 kg

Gas Bottle Tare Weight

Tare weight is the empty weight of the gas bottle-cylinder.  
Along with the gas bottle dimensions, they can vary greatly by manufacturer and date of manufacture. 
For example, older bottles tend to be heavier than more recent versions.

How is LPG Gas Measured for Homes

When Liquefied Petroleum Gas – LPG – is used in the home, LPG gas is typically measured in kilograms. LPG gas in gas bottles is weighed and the price is based on the weight of the gas (e.g. 45kg). When produced, stored or transported, bulk LPG gas is measured in tonnes (e.g. 1,000kg).

Home LPG gas is also measured in litres of gas, if delivery is made by a tanker truck, instead of by gas cylinder exchange. The tanker truck has a gas meter attached to a hose reel that measures the gas as it is pumped into the customers' vessels.

A common way LPG gas is measured and selling LPG is by weight, in kilograms. There are different sizes of LPG gas bottles and the gas is sold based on the contents of a full bottle. Home LPG gas is measured in 45kg gas bottles.  BBQ gas is typically LPG gas measured and supplied in 9kg gas bottles. These numbers represent the weight of the gas, excluding the tare weight of the gas bottle.

Measuring LPG by Pressure

When LPG (propane) is stored in a gas bottle, it is under pressure. 

The term “pressure” refers to the average force per unit of area that the gas exerts on the inside walls of the gas bottle. 

The pressure is measured in kilopascals (kPa).

“Bar” is yet another unit of measure for pressure.  1 Bar = 100 kPa, so it is metric based but not an SI unit of measure.

LPG pressure can vary greatly based on temperature.

The level of fill in the gas bottle comes into play when the LPG is being used, as it affects the rate of vapourisation. 

As LPG is a liquefied gas, the pressure inside the cylinder will remain the same from full to empty (after the last of the liquid LPG is used), then the pressure will fall quickly as the last of the LPG vapour is used.

The use of Pressure as a measurement in LPG use is very limited. 

A steady Pressure only shows that liquid LPG is inside the cylinder, and not how much liquid is left.

In the US, pressure is measured in pounds per square inch (psi). 

Psi is defined as 1 pound of force applied per square inch.   As a comparison, 1 psi = 6.89476 kPa.

LPG Gas Unit Conversion Table: kg, Litres, MJ, kWh & m³

LPG gas conversion value table with kg, litres, MJ, kWh and cubic meters.
Note that this chart is for propane LPG and the m3 column refers to gaseous LPG

LPG Cylinder Capacity in Litres

LPG cylinder capacity in litres illustration shows full at 80%LPG cylinder capacity in litres is based on filling it to 80%, to allow for expansion. The other 20% is referred to as ullage. If an LPG cylinder capacity in litres is 80 litres, the actual ‘water capacity’ is 100 litres.

LPG cylinder capacity in litres for a 45 kg LPG cylinder is about 88 litres and is the most popular size for both domestic and commercial applications. The LPG cylinder capacity in litres can change if sold by the kg, as propane has 1.96L per kg whilst butane has only 1.724L per kg. This is because the two gases have different specific gravity.

LPG cylinder capacity in litres goes from a small LPG cylinder capacity of 7.25 litres for a 3.7 kg LPG cylinder to a large LPG cylinder capacity of 411 litres for a 210 kg LPG cylinder. The chart below shows LPG cylinder capacity in litres for the 7 most popular sizes of LPG cylinder based on 1.96 litres of LPG cylinder capacity per kilogram (1 kg = 1.96 L).

90 kg LPG cylinder capacity is about 176 litres and is popular for tanker fill and underground storage, for both domestic and commercial applications.

210 kg LPG cylinders capacity is about 411 litres of LPG and is the largest cylinder for both domestic and commercial applications. It is different because it has 2 outlets, one to withdraw gas and one for liquid, typically used for decanting.

14.2 kg LPG cylinder capacity is about 27.8 litres and is the most popular cooking gas cylinder size in India.

LPG cylinder capacity in litres is considered full at 80%, to allow for ullage. Ullage is the empty LPG cylinder capacity at the top of the cylinder that provides room for expansion of the gas vapour.

See accompanying illustration of LPG cylinder capacity in litres full at 80%.

LPG Cylinder Capacity in Litres Comparison Chart

LPG Cylinder Capacity in Litres Chart

LPG Cylinder Size in kg

LPG Cylinder Capacity in Litres
3.7 7.25
8.5 16.6
15 29
18 35
45 88
90 176
210 411

This chart of LPG cylinder capacity in litres is based on propane at 1 kg = 1.96 L

The capacity of an LPG cylinder in litres can change if sold by the kg, as propane has 1.96 L per kg whilst butane has only 1.724 L per kg. This is because the two gases have different specific gravity.

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Propane Gas Unit Conversions Table: Pounds, Gallons, BTU, Therms & ft³

For our friends in the USA:

Propane gas unit conversion values in US gallons, pounds, BTUs, therms and cubic feet. The table below shown covers most of the common units of measure and gas bottle-cylinder sizes for the USA.

Propane Gas Unit Conversion Formulas (US Units of Measure):

  • Propane Gallons to Pounds Gas Unit Conversion:  1 Gal = 4.23 lbs

  • Propane Pounds to Gallons Gas Unit Conversion:  1 lb = 0.24 Gallons

  • Propane Gallons to BTU Gas Unit Conversion:  1 Gal = 91,502 BTU

  • Propane Pounds to BTU Gas Unit Conversion:  1 lb = 21,594 BTU

  • *Propane Gallons to ft3 Gas Unit Conversion:  1 Gal = 36.38 ft3

  • *Propane Pounds to ft3 Gas Unit Conversion:  1 lb = 8.59 ft3

  • BTU to Therms Gas Unit Conversion:  1 BTU = 0.000009993 Therms

  • Therms to BTU Gas Unit Conversion:  1 Therm = 100,067 BTU

*Note that these are Liquid to Gas unit conversions

Learn More About USA Units of Measure for Propane

Propane gas conversion tables for pounds, gallons, BTU, therms & ft3
Note that the ft3 column refers to gaseous propane

45 kg LPG Gas Bottles45kg gas bottle - cylinder

45 kg gas cylinder sizes are the most common size for home use

This is the size used for our Home Gas Bottle Exchange Service

They are also used with our Automatic Tanker Delivery Service

A typical installation has two 45 kg gas bottles

Capacity: 88 litres

Diameter: 375 mm

Height: 1250 mm

 

90 kg LPG Gas Cylinders90kg LPG gas cylinder sizes / gas bottle sizes

90 kg gas cylinder sizes are the second most common size for home use

This size is commonly used with our Automatic Tanker Delivery Service

A typical installation has one cylinder

90 kg is also used with our Underground LPG Gas Storage System

Capacity: 176 litres

Diameter:  510 mm

Height:  1380 mm

 

210 kg LPG Gas Cylinders

210kg LPG gas cylinder sizes / gas bottle sizes

210 kg gas cylinder sizes are provided for high volume use

Larger storage vessels are also available, when needed

Filling is via our Automatic Tanker Delivery Service

Capacity: 411 litres

Diameter:  760 mm

Height:  1450 mm

 

 

 

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The information in this article is derived from various sources and is believed to be correct at the time of publication. However, the information may not be error free and may not be applicable in all circumstances.