How Many Gallons In a 33.5 lb Propane Tank? (Propane Tank Sizes)

How Many Gallons In a 33.5 lb Propane Tank

Propane is one of the most useful fuel sources around and many different appliances depend on it every single day. Different uses will require different amounts of propane, however, so you may be wondering, how many gallons are in a 33.5 lb propane tank?

A 33.5 lb propane tank can hold around 7.5 – 7.8 gallons of propane fuel, which is between 34 and 36 litres. This size of the propane tank is reasonably portable while still having a decent capacity and is most commonly used in forklifts. It is heavier than some of the smaller tanks that are available but will need topping up less frequently.

This article will tell you everything you need to know about this particular size of a propane tank, including exactly how much fuel one can contain, how long it is likely to last with common appliances, and what you can do to top one up when it starts to run dry.

Exactly How Much Fuel Can a 33.5 lb Propane Tank Hold?

A 33.5 lb propane tank has a maximum capacity of about 7.8 gallons or 35.5 litres. It is one of the larger tank sizes that are still reasonably portable. The 33.5 lb tank is quite a specific size of tank as opposed to the more common 20 lb or 40 lb tanks.

The exact amount of fuel inside of a propane tank will vary slightly depending on how it was filled and the specific shape of the tank itself. The average amount of fuel inside of a filled 33.5 lb tank is around 7.5 gallons or 34 litres.

Read also: Cheapest Propane Refill Near Me (Tanks Exchange Locations)

How Large is a 33.5 lb Propane Tank?

Most 33.5 lb propane tanks are similar dimensions although the specific measurements can vary depending on the shape and style of the tank. The majority of tanks this size are standardised vertical cylinders that are designed to fit with most propane-fuelled appliances.

The most common measurements for a 33.5 lb propane tank are:

  • Width: Approximately 12 inches
  • Depth: Approximately 12 inches
  • Height: Approximately 27 inches

Tanks of this size tend to be similar in diameter to the more common 20 lb size, but much taller.

How Much Does a 33.5 lb Propane Tank Weigh?

The weight of any propane tank is highly dependent on the amount of fuel that is currently contained inside. The 33.5 lb descriptor for the tank is actually referring to the liquid weight that the container can hold, but the tank itself will have an empty weight as well.

The empty tank weight of a propane tank is usually labelled as the “tare weight” (TW) and you can often find it engraved on the outside of the tank.

To find out the total weight of a 33.5 lb propane tank you will need to combine the current weight of the fuel inside with the weight of the tank when empty.

The TW of a 33.5 lb propane tank will depend on which material the tank is made from. 33.5 lb aluminium tanks weigh around 24 lb when empty, but you can buy steel tanks as well at this size which are much heavier, weighing around 36 lb.

The total weight of one of these tanks when full is likely to be:

  • 33.5 lb Aluminium Tank: 33.5 lb + 24 lb = 57.5 lb
  • 33.5 lb Steel Tank: 33.5 lb + 36 lb = 69.5 lb

Read also: How Much Does It Cost To Fill A Propane Tank For A House

What Are 33.5 lb Propane Tanks Used For?

A 33.5 lb propane tank is quite a particular size. As opposed to the more commonly found 20 lb or 40 lb tanks, 33.5 lb propane tanks are most often used to power forklift trucks. 90% of all forklifts are powered by 33.5 lb liquid propane tanks.

In fact, a lot of the tanks of this size that are on the market are specifically labelled as forklift tanks. They are often specialized for this purpose as they have a liquid draw design, durable construction and the ability to be installed horizontally.

Read also: How Many Gallons In a 500 lb Propane Tank? (Propane Tank Sizes)

How Long Will a 33.5 lb Propane Tank Last?

Whenever you are buying a tank of fuel, one of the main factors in deciding which size to choose is how often you are going to need to replace it. Smaller tanks are more portable and lighter to carry, but they can run out far too quickly for certain purposes.

The actual amount of time that your tank will last, however, depends entirely on the type of machinery that you are working with. Some appliances burn through fuel a lot faster than others, and some don’t need to be powered for many hours throughout the day.

For example, the average camper only uses about ½ lb of propane per day, so smaller tanks will last for a long time. On the other hand, a medium-sized grill tends to use around 1 lb of propane every hour and a larger grill can use twice that. A forklift truck can use over 8 lbs per hour, whereas the average home heating system uses a gallon.

A 33.5 lb propane tank, therefore, will usually last for approximately:

  • Forklift: 5 hours
  • Home Heating: 8 hours
  • Large Grill: 17 hours
  • Medium Grill: 34 hours
  • Camping: 70 days

To determine exactly how much time you are going to get out of your propane tank, you will need to refer to the BTU usage of the appliance you are powering.

Read also: How Many Gallons In a 40 lb Propane Tank? (Propane Tank Sizes)

What Are BTUs?

You will often see BTUs as descriptive measurements referring to both fuel sources and the appliances that are powered by them.

BTUs (British Thermal Units) are a way of measuring how much heating energy a fuel source is able to provide, as well as how much heat energy an appliance burns through over time.

Different fuel sources provide different amounts of energy when they burn, so they will have different BTUs. The hourly BTU usage of appliances will also vary greatly.

One BTU is the amount of energy required to raise the temperature of one pound of water by one degree Fahrenheit.

How Many BTUs Are There in a 33.5 lb Propane Tank?

One pound of propane provides 21,600 BTUs. For reference, coal only provides around 12,500 BTUs. You can use this number to calculate the number of BTUs that any quantity of propane still has left to output. For a full 33.5 lb tank, you will have 723,600 BTUs in total.

With this total, you can start to determine exactly how long your tank will run your appliances for by looking at the BTU usage on the appliance. You can find this number for almost any equipment that is powered by a fuel that burns.

If you have a patio heater that uses 40,000 BTUs per hour, then you can divide the total BTUs in your fuel by this amount to figure out how many hours you have left. With a 33.5 lb tank that is filled up at 723,600 BTUs, you would be able to power this patio heater for around 18 hours.

What Do You Do When Your 33.5 lb Propane Tank Runs Out?

For some industrial purposes, like powering forklift trucks, you will probably run out of fuel in one of these tanks pretty quickly, so do you need to start buying new ones?

 Rather than spending a lot of money and wasting resources purchasing an entirely new tank, you can take your empty ones to a refilling station and exchange them, or get them topped up.

Where Can You Refill A 33.5 lb Propane Tank?

The adaptors for 33.5 lb propane tanks are the same as those for the most common 20 lb size, so almost any location that deals in propane will be able to top your tanks up for you.

Many gas stations offer propane refilling services, as do a lot of hardware stores, vehicle repair and maintenance places, and camping supply stores.

There are also many companies that specifically offer propane refilling, either at individual locations or as a delivery service (though this will usually incur an extra fee).

U-Haul actually has the largest network of propane refilling stations in the United States, so they may well be your best bet. The company operates more than 1,100 different refill locations all over the country so there is probably one conveniently located for you wherever you are.

How Do You Know How Full a 33.5 lb Propane Tank Is?

It is really hard to keep track of how much propane you are using but you can easily find out how much is left in the tank in other ways.

You can either weigh the tank and compare its current weight to how much it would weigh if it were empty, or you can use a tank gauge. A tank gauge has a reader that shows you how full your tank is by percentage, which you can use to calculate the exact quantity inside.

To figure out how much fuel you have left by weight:

  • First, find the empty tank weight by looking at the TW number.
  • Then, place your tank on a set of scales (Make sure the set you are using has a maximum capacity greater than 100 lbs).
  • Then, find the difference between the current total weight of your tank and the empty tank weight.
  • Finally, you can multiply the weight of fuel you have remaining to determine how many BTUs you have left.

For example, if your 33.5 lb tank has a TW of 24 lbs and it currently weighs 35 lbs, then you have 11 lbs of fuel remaining. This is equal to around 237,600 BTUs.


A 33.5 lb propane tank can hold about 7.8 gallons of propane fuel or around 35.5 litres. These tanks are large enough to power many home appliances for a reasonable amount of time while still being relatively portable.

Within a tank of this size, you can expect to house a total of around 723,600 BTUs worth of propane.

This particular tank size is quite specific and is most commonly used to fuel forklifts. They are almost always refillable and there are many locations around the country where you can take your tanks to get them topped up.

Read also: Does Walmart Refill Propane Tanks (With 6 Filling Stations)


Mike Gilmour

Hi, I'm Mike, co-founder, and editor of RV and Playa. My passion is traveling (with my RV) and enjoying the day at the beach (Playa)! Well, I originally created this blog as a way to share what I've learned by experimenting with the RV lifestyle, and I want to help others develop in life through new skills and opportunities.

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