• Last Updated: 08 December 2021

# How Long Will a 9kg Gas Bottle Last – How Long Does a Gas Bottle Last – How Long Does BBQ Gas Last – How Long Does Patio Gas Last

### 9kg BBQ Gas Bottle Capacity Facts for How Long Will a 9kg Gas Bottle Last:

9kg in pounds = 19.8416 lbs

8.5kg in pounds = 18.7393 lbs

### How Long Does a Gas Bottle Last – How Long Does BBQ Gas Bottle Last – How Long Does Bottled Gas Last

A typical patio heater consumption would be about 35MJ (33,173 BTU). Since a 9kg gas bottle has 441MJ (417,987 BTU) of energy content, a BBQ gas bottle will last 12 hours in a heater rated at 35MJ. So, how long does a BBQ gas bottle last in a heater depends on the burner size.

### How Long Does a LPG Cylinder Last

How long does a LPG cylinder lasts depends on the cylinder size and the gas load upon it. Assuming it is a 45 kg LPG cylinder, these are some examples:

♦ 16 L/min Hot Water used for 30 minutes per day = a 45kg gas bottle (45 kg LPG cylinder) lasts 35 days

♦ 9 MJ Cooktop Burner used for 90 minutes per day = a 45kg gas bottle (45 kg LPG cylinder) lasts 163 days

♦ 15 MJ Gas Heater used for 3 hours per day = a 45kg gas bottle (45 kg LPG cylinder) lasts 37 days

♦ 25 MJ Gas Fireplace used for 3 hours per day = a 45kg gas bottle (45 kg LPG cylinder) lasts 29 days

Assuming it is a 14.2kg cooking gas bottle, it would last from about 9 days to 81 days, depending upon burner size and amount of use. If you use a small 5MJ burner for 30 minutes per day, the gas bottle will last 81 days. If you use a large 15MJ wok style burner for 90 minutes per day, the gas bottle lasts 9 days.

### How Long Does LPG Last

How long does LPG last… indefinitely. LPG shelf life is unlimited. The only limiting factor is the gas bottle itself. Assuming it is taken care of and not allowed to rust, it could last 20 years or more. Gas bottles typically need re-ispection every 10 years to refill the gas bottle but you can use it beyond 10 years, if safe to do so.

### Calculations Based on MJ/hr or BTU/hr for How Long Does a Gas Bottle Last

All outdoor gas appliances — like BBQs and patio heaters — are rated by energy consumption, in either megajoules (MJ) or BTUs per hour.

How long does a gas bottle last is based on its known energy content, which is based on the cylinder capacity and the energy content per unit of the LPG (propane).

By dividing the hourly consumption of your gas appliance into the available energy content of the LPG gas bottle, you get the number of hours of how long does a gas bottle last.

There are 441 MJ in a full 9kg BBQ gas bottle.

Here are some estimates on how long does a gas bottle last:

How Long Does a Gas Bottle Last

#### How Will Does a 9kg BBQ Gas Bottle Last?

Traditional BBQ 1 Burner 4 Burners
• 15MJ Burners 29.4 hours 7.3 hours
• 17MJ Burners 25.9 hours 6.5 hours
Compact BBQ 1 Burner 2 Burners
• 7.5 MJ Burners 58.8 hours 29.4 hours
• 10MJ Burners 44.1 hours 22 hours
Gas Patio Heaters 1 Burner
• 35MJ Burner 12.6 hours

Table Top Heater 1 Burner
• 12MJ Burner 36.7 hours

• Duration Shown assumes that you use the burners on the maximum setting.

• Gas consumption would be less, and the duration longer, on lower settings.

• Result numbers have been rounded.

### How Long Does Patio Gas Last

Patio gas will last 12 hours with a 35 MJ patio gas heater, based on a 9kg (20 lb) patio gas bottle. This is assumes using the HIGH setting and will last longer if turned down.

##### ♦ Patio gas will last ≈ 36 hours with 12 MJ Table Top Heater

Here are some estimates on how long patio gas will last:

#### How Long Does Patio Gas Last

Traditional BBQ 1 Burner 4 Burners
• 15MJ Burners 29.4 hours 7.3 hours
• 17MJ Burners 25.9 hours 6.5 hours
Compact BBQ 1 Burner 2 Burners
• 7.5 MJ Burners 58.8 hours 29.4 hours
• 10MJ Burners 44.1 hours 22 hours
Gas Patio Heaters 1 Burner
• 35MJ Burner 12.6 hours

Table Top Heater 1 Burner
• 12MJ Burner 36.7 hours

• Based on 9kg or 20lb patio gas bottle

• Duration Shown assumes that you use the burners on the maximum setting.

• Gas consumption would be less, and the duration longer, on lower settings.

• Result numbers have been rounded.

### How Long Does a 4.5 kg Gas Bottle Last

A 4.5 kg gas bottle does last about 3 to 4 days cooking a meal a day on a 4 burner BBQ grill, assuming a one hour cook time per meal. A 9kg gas bottle (patio gas) will last about 15 hours, when cooking with a small 2 burner compact BBQ used on high. It will last even longer on lower settings or if only one burner is turned on.

Patio gas (4.5 kg) will last 6 hours with a 35 MJ patio gas heater. This is based on using the HIGH setting and will last longer if turned down.

A small table top heater will last about 18 hours on a 4.5 kg gas bottle. A 4.5 kg BBQ gas bottle will last a little over 3 hours with a large 4 burner BBQ. A 1-burner compact BBQ will last 22 hours on a 4.5 kg gas bottle. These durations all assume the burners are set on maximum.

### How Long Does a 4.5 kg Gas Bottle Last Chart

#### How Long Does a 4.5 kg BBQ Gas Bottle Last?

Traditional BBQ 1 Burner 4 Burners
• 15MJ Burners 14.7 hours 3.6 hours
• 17MJ Burners 13 hours 3.2 hours
Compact BBQ 1 Burner 2 Burners
• 7.5 MJ Burners 29.4 hours 14.7 hours
• 10MJ Burners 22 hours 11 hours
Gas Patio Heaters 1 Burner
• 35MJ Burner 6.3 hours

Table Top Heater 1 Burner
• 12MJ Burner 18.3 hours
• Duration Shown assumes that you use the burners on the maximum setting.
• Gas consumption would be less, and the duration longer, on lower settings.
• Result numbers have been rounded.

### How Long Does a 13kg Gas Bottle Last on a BBQ

How long does a 13kg gas bottle last on a BBQ would be anywhere from about 9.4 hours for a large 4-burner BBQ to 84.7 hours for a compact 1-burner BBQ.

A 13kg is 44% larger than a 9kg so if you multiply the 9kg figures above times 1.44, you will get how long a 13kg gas bottle lasts.  For example, a traditional BBQ with 4 x 15MJ burners will last 10.5 hours (7.3 x 1.44 = 10.5 hours). Or, even easier, just use the 13kg chart below:

How Long a 13kg BBQ Bottle Lasts

#### How Long Will a 13kg

Traditional BBQ 1 Burner 4 Burners
• 15MJ Burners 42.3 hours 10.5 hours
• 17MJ Burners 37.3 hours 9.4 hours
Compact BBQ 1 Burner 2 Burners
• 7.5 MJ Burners 84.7 hours 42.3 hours
• 10MJ Burners 63.5 hours 31.7 hours
Gas Patio Heaters 1 Burner
• 35MJ Burner 18.1 hours

Table Top Heater 1 Burner
• 12MJ Burner 52.8 hours
• Duration Shown assumes that you use the burners on the maximum setting.
• Gas consumption would be less, and the duration longer, on lower settings.
• Result numbers have been rounded.

### How Long Will a 20 Pound Propane Tank Last – How Long Does a Gas Bottle Last – How Long Does Patio Gas Last

How long will a 20 pound propane tank last (how long does BBQ gas last) is determined by dividing the hourly consumption of your gas appliance into the available energy content of the propane BBQ gas tank, you get the number of hours how long does a gas bottle last (how long does patio gas last).

There are 420,909 BTU in a full 20 pound propane tank.

Here are some estimates for how long does a gas bottle last (how long does patio gas last):

 How Long Will a 20lb Propane Tank Last – How Long Does a Gas Bottle Last Traditional BBQ 1 Burner 4 Burners • 14,220 BTU Burner 29.6 hours 7.4 hours • 16,100 BTU Burner 26.1 hours 6.5 hours Compact BBQ 1 Burner 2 Burners • 7,110 BTU Burner 59.2 hours 29.6 hours • 9,480 BTU Burner 44.4 hours 22.2 hours Gas Patio Heaters 1 Burner – • 33,180 BTU Burner 12.7 hours – Table Top Heater 1 Burner – • 11,380 BTU Burner 37.0 hours – • Duration Shown assumes that you use the burners on the maximum setting.  • Gas consumption would be less, and the gas bottle will last longer, on lower settings.  • Result numbers have been rounded.

Read more to learn exactly how to calculate how long does a gas bottle last for your home…

### Basic Background Information for How Long Does a Gas Bottle Last

Appliance gas consumption is expressed in Megajoules or MJ of energy.

The total MJ consumption is a function of the burner size and the number of burners.

For example, a traditional sized gas BBQ would have 4 or 6 burners and these usually range from 12MJ to 19MJ each.

15MJ to 17MJ burners are the most typical.

Some of the new compact portable BBQs would have only one of two burners and the burners would range from around 7.5MJ to 11MJ.

10MJ would be typical.

Just to make it a bit more challenging, some BBQ manufacturers, like Weber, rate their burners in BTU.

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

One litre of LPG has approximately 25MJ of energy content.

An 8.5kg gas bottle contains just a bit less than 17 litres or approximately 417MJ of energy.

### How To Calculate How Long Does a Gas Bottle Last

So, to determine how long the 8.5kg gas bottle will last, you just divide 417 by the MJ rating of the BBQ or patio heater.

You should be able to find the MJ rating of the burners in your Owner’s Manual or on the manufacturer’s web site.

### BBQ Example 1:

You turn on 2 burners set to high.

Each burner is rated at 15MJ so that’s 15×2=30MJ/hour of gas consumption.

Then divide that into 417 (the number of MJ in the 8.5kg bottle) to get the running time: 417÷30=13.9 hours how long does a gas bottle last.

### BBQ Example 2:

You have a single burner compact BBQ with a 10MJ rated burner.

So 417÷10=41.7 hours of running time how long does a gas bottle last.

To make it even easier, you can use the table below.

### In the USA?

If you are in the USA, a typical 20 pound propane tank is filled with 17 pounds of propane (LPG).

This converts to approximately 7.7kg, 15.1L or 377MJ (357,000BTU).

So, you would need to reduce the times, in the table below, by about 9% for how long does a gas bottle last.

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Answers for how long does a gas bottle last shown are just examples, as MJ ratings will vary by manufacturer and model:

### A Megajoule or MJ Probably Isn’t What You Think

What is a megajoule and why does it matter when I buy a gas BBQ or heater?

Many people think they know but you might be surprised by the real answer.

### Gas Consumption = MJ

Megajoules per Hour (MJ/hr) ratings on appliances actually indicate the gas consumption of the appliance, not the heat output.

It is often expressed as just MJ.

On the other hand, heat output must also take into account the relative energy efficiency ratings of the models being compared.

How is it pronounced?  Say it as if it were spelled “mega jewel” or “mega jewels”, not “mega jowl”.

### Heat Output = kWh

Kilowatt Hour (kWh) is how gas heater 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 on some types of appliances.

Appliance output is often expressed as just kW.