# How Many Hours Does A 20lb Propane Tank Last?

A 20 lb propane tank contains around 4.73 gallons of fuel, but it would depend upon a number of varying factors to establish exactly how long this amount of propane would last for, such as:

The length of time the propane in the tank was being burned for

The intensity of the heat, i.e. Is the appliance on full power?

The frequency of use

The type of appliance being used

The number of appliances using the propane tank

The BTU rating of each appliance it is being used for.

The BTU rating is derived from the unit of measurement that is utilised in order to work out the amount of time the Propane will burn for. The method used is British Thermal Units per hour (BTU/h). This equates to the amount of thermal energy that it takes to heat a pound of water from 3.9 degrees C to 4.4 degrees C and is equivalent to just over one kilojoule in energy content.

A 20lb tank will burn at approximately 91,600 BTU per gallon of Propane, which equates to about 433,000 BTU for the entirety of the tank. In order to work out how long your tank will last you will need to take into account all the above mentioned parameters.

For the sake of argument, let's take an example of a Propane powered cooker using 4000 BTU/h. Using the equation 433,000/4000, the answer returned shows it will take over 108 hours to burn the propane content of the tank, which is exactly four and half days you could have the stove on for at full power before it ran out.

This is obviously an extreme example as it's unlikely you'd be running any appliance at full power for almost an entire working week. Using the conditions relevant to your situation you could accurately estimate how long a 20 lb tank would last."
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You can calculate your burn time based on BTU usage of your grill. A 20 pound propane tank contains 4.73 gallons of LPG. 1 gallon of LPG contains 91,690 BTUs. This gives a total of 433,693.7 BTUs of energy. Now, look on your grill for the BTU/hour output. For example, I have a 4-burner (477 square inch cooking area), 50,000BTU/hr grill, so a full tank will give me 8.67 hours with all 4 burners on high. A smaller grill will obviously require less fuel, and therefor increase your burn time per tank of propane.
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