Whether you use propane tanks for daily cooking and heating or the occasional outdoor barbeque, the last thing you want is to run out of gas. Sometimes, you may have to settle for some takeout while waiting for your propane delivery to arrive. Fortunately, you can tell how much gas is left in your tank by weighing it.

A propane tank with a capacity of 20 lbs weighs 17 lbs when empty, as shown by the tare weight marked near the handle. Its capacity plus tare weight means it weighs 37 lbs when full. To calculate the remaining gas in the tank, subtract its weight from 37 lbs. 

Keep reading if you’re concerned about how much gas your tank has left and if you want to know what type of tank best suits your needs. This article will show you different methods of measuring the remaining gas in your tank and various gauges you can use to monitor propane levels. 

Measuring the Gas Left in Your Propane Tank

In this day and age, you would think that propane tanks would come standard with a gauge to help you determine how much gas you have left. However, that isn’t the case. Fortunately, there are different methods you can use to tell if you have enough gas for your next cooking session. 

Weigh the Tank

You check how much gas is in your propane tank by weighing it and subtracting the weight from how much an empty tank weighs. You can tell how much a propane tank weighs without its contents by checking the numbers stamped near its handle.

Below are the markings you would typically find on the tank’s collar:

  • TW (Tare Weight): Indicates how much the cylinder weighs without its contents (in lbs).
  • WC (Water Capacity): Used to indicate how much gas the cylinder can hold for refilling purposes.
  • Manufacture Date: The manufacture date appears as month and year (01 20 = January 2020). A tank is considered expired 12 years after its manufacturing date in the United States.

You can use a standard or luggage weighing scale to weigh the propane tank. Once you have the weight, subtract that number from the tank’s tare weight.

So, if a tank with a 17 pound tare weight weighs 25 lbs, it has 8 lbs of gas left inside it.

(Current weight 25 lbs – Tare Weight 17 lbs = 8 lbs).

To know how much gas is left in gallons, divide the weight of the remaining gas by 4.2 pounds, which is the weight of one gallon of propane.

Using this formula and the example above, we know that 8 lbs of gas is equivalent to 1.9 gallons (8 lbs or 3.6 kg of remaining gas / 4.2 lbs or 1.9 kg per gallon = 1.9 gallons or 8.6 liters).

Use the Hot Water Technique

You can use the hot water technique if you don’t want to lift a heavy propane tank to check how much gas you have left. This method won’t give you an exact figure, but it will let you know if a replacement is just around the corner.

Here’s how to use hot water to determine your propane tank’s weight:

  1. Start by pouring hot water over the side of the tank. Pour enough water so the side of the tank is wet from top to bottom. Since the tank is made of metal, the hot water should make the tank feel warm.
  2. Next, run your hand along the side of the tank, starting from the top. You should feel the tank get cooler as you move your hand down. The point where the temperature changes indicates the level of gas inside the tank.

Liquid propane absorbs heat, so any cool part of the cylinder wall tells you there is still gas behind it. If the tank stays warm until your hand reaches the bottom, that probably means you’re out of gas. 

The YouTube video below demonstrates how to check your tank’s propane level using the hot water method:

You may also like to read: How Hot Can a Propane Tank Get Before It Explodes?

Calculate Based on Your Consumption

One way to estimate how much gas you have left is by monitoring your consumption. You can figure out how long a full propane tank will last based on your appliance’s BTU (British Thermal Unit) rating. One BTU is the amount of energy needed to heat one pound of water to one degree Fahrenheit. 

The BTU ratings of burners on a household cooktop or gas stove range between 500 to 18,000 BTU. You should be able to find a BTU value on your burners, or you can also check the owner’s manual.

Once you have your burner’s BTU rating, you can compute how many hours a full propane tank will last.

For example:

BTU Rating of appliance = 10,000 BTU / hour

1 gallon of propane = 91,500 BTU

1 gallon of propane = 4.2 lbs

Propane Tank = 20 lbs (full)

20 lbs / 4.2 lbs = 4.76 gallons

4.76 gallons x 91,500 BTU = 435,540 BTU

435,540 BTU / 10,000 BTU = 43.6 hours

Once you know how many hours your tank will last, you can calculate when a refill is due based on your usage. Based on the example above, using a 20 lbs propane tank for an hour a day will last a little over 43 days. This computation is based on the burner’s maximum output, so using a lower flame will extend the number of hours.

Install an External Gauge

The most convenient way to tell how much gas you have left is to install an external gauge. Most gauges can be quickly installed and provide a hassle-free way to check your remaining gas. 

The Generep Universal Propane Gauge can be installed without tools and comes with a propane regulator, which automatically shuts off when it detects excessive gas flow. Any propane tank user will benefit from the convenience and safety this gauge provides. 

Different Kinds of Propane Tank Gauges

Although they all serve the same purpose, there are different kinds of propane tank gauges you can choose from:

  • Inline pressure gauges: Determines how much gas you have left by measuring the pressure in the gas line that travels from the tank to your appliance. 
  • Propane Scales: Similar to a luggage scale, this comes with a hook, which you use to lift the tank. This gauge is calibrated based on the size of the tank and tells you how much gas is left based on how much the tank weighs. 
  • Tank Float Gauges: This gauge works like the fuel float in your car’s gas tank. It floats on top of the liquid propane and gives an approximate percentage of how much liquid there is in the tank. 
  • Smart Wireless Propane Tank Scale: This uses a battery-operated apparatus to weigh your tank and works with Bluetooth to connect to your smartphone. You can view the propane level using an app on your phone. 

Final Thoughts

You can tell how much gas is left in your tank by weighing it and subtracting its weight from the tare weight. 

Another way to check how much remaining gas you have is by pouring hot water along the side of the tank and checking where the temperature changes.

If you’re craving some arithmetic, you can also compute how long the gas in your tank will last based on your appliance BTU rating per hour. 

However, if you can’t be bothered with any of that, installing a tank gauge is the easiest way to check your propane level. 

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