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Propane Tank Sizes: Which One Is Right for Your RV?

Propane Tank Sizes: Which One Is Right for Your RV?

If you’ve got propane-fueled appliances onboard your RV, then you know how critical it is to keep a sufficient amount of propane in the tank to keep them running. But, propane tank sizes vary, which means that the amount of propane you have available to run your refrigerator, furnace, water heater, and stove will vary as well.

In this post, we’re taking a look at common RV propane tank sizes as well as the different types of RV propane tanks found on most motorhomes, travel trailers, and fifth wheel RVs, with an eye toward making sure you don’t run out of propane just when you need it the most!

What Are the Different Types of RV Propane Tanks?

Propane tanks come in a variety of sizes, but there are also a few different types of propane tanks used by RVers.

Before we get into size, let’s take a quick look at the differences in the types of propane tanks most often found on RVs.

ASME Propane Tank

An ASME tank is a liquid propane tank made of heavy steel. These tanks are designed for permanent applications, such as those found permanently mounted on an RV or outside a home or business.

The American Society of Mechanical Engineers (ASME) governs the design and standards of these tanks (hence the name). As such, they don’t require periodic recertification, but they should be regularly inspected for rust, damage, and leaks.

ASME tanks permanently mounted in an RV can range from a 30 lb propane tank on a Class B motorhome up to an 80 to 100 pound tank like those found on larger Class A motorhomes.

But it can also be a large, permanently placed external LP (liquid propane) tank located at a site where an RV would be likely to hook up for a longer period. These are static and are generally refilled by mobile propane services.

Most ASME tanks have propane tank gauges, but it’s possible to check how much propane is left in any propane tank even without a gauge. See our post on how to check tank levels without a gauge for more information.

In the following video, we connect our rig to a large external tank for a winter stay in one location. This video could be helpful to you if you should ever want to do the same.

DOT Propane Cylinder

DOT cylinders are removable propane tanks that generally come in three sizes: 20-pound, 30-pound, and 40-pound cylinders. The 20-pound propane tanks (most commonly found in use on home BBQ grills or patio heaters) being perhaps the most popular.

You’ll often see one or two of these 20-pound tanks mounted on the tongue or bumper of a travel trailer, or inside a compartment of a truck camper. Larger RVs, like big fifth wheels, will often have one or more 30- or 40-pound cylinders.

Approved by the Department of Transportation (DOT), these cylinders are designed specifically for portable applications. They must be replaced or recertified every 12 years (10 years in Canada).

Flame King YSN-201 20-Pound Steel Propane Tank Cylinder with Type 1 OPD Valve, White
  • High grade steel welded propane cylinder
  • Premium OPD valve assembly
Flame King YSN-301 30 Pound Steel Propane Tank Cylinder with Type 1 Overflow Protection Device Valve DOT and TC Compliant, White (Package May Vary)
  • Safety first - Flame King tanks are Pre-purged vacuum ready for filling with LP gas - they are x-ray and hydrostatic tested plus Department of...
  • High quality - each tank is constructed from high grade Welded Steel and powder coated for long lasting durability.
Flame King YSN401a 40 Pound Steel Propane Tank Cylinder with Overflow Protection Device Valve,White
  • Safety first - Flame King tanks are Pre-purged vacuum ready for filling with LP gas - they are x-ray and hydrostatic tested plus Department of...
  • High quality - each tank is constructed from high grade Welded Steel and powder coated for long lasting durability.

Small Portable Propane Tank

We’d be remiss not to mention the little portable tanks often used by travelers in converted vans, car campers, and even tent campers. These little tanks are available in many grocery and big box stores and contain a gallon of propane for use with items such as small portable propane stoves and heaters.

Most RVs, however, are more likely to have a built-in ASME tank or a DOT cylinder or two mounted on the tongue or bumper of the rig.

What Size Propane Tank Is Best for Your RV?

The answer to this question depends on several factors. First, let’s acknowledge that if you’ve got an RV with a built-in ASME propane tank, you really don’t have much choice but to use that tank, whatever capacity it may be.

However, if you’ve got an RV that uses DOT propane cylinders, you have choices, as noted in the previous section. So for you, the question of what size propane tank is best is more pertinent.

The way to determine which size tank is best for your RV lifestyle is to consider the propane-fueled appliances you use and then consider how much propane each type of appliance tends to consume on average.

How Much Propane Do Your RV Appliances Use?

Propane use by RV appliances varies tremendously. For instance, if you’ve got a small Class B RV to heat and we’ve got a large Class A RV to heat, we’ll use very different amounts of propane to heat our respective rigs.

How well a rig is insulated also comes into play. And the efficiency of those appliances even matters, as does appliance maintenance and other factors.

Your particular RV lifestyle must also be considered (i.e. how much you cook in the RV, what climate you tend to camp in, what type of refrigerator you use, etc.)

So, really, there’s no simple way to determine the average propane use of any particular RV appliance.

However, we can make certain generalizations, and then you can apply those to your RV and RV lifestyle.

For example, if you look at our post asking “how much propane does an RV furnace use” you’ll see that you first need to identify the BTU (British Thermal Units) rating of your RV’s furnace. (Note that BTU is a measurement of heat, so the higher the BTU rating of your appliance, the more heat it can produce and, thus, the more propane it will use).

The energy content of one gallon of propane is roughly 90,000 BTUs. If you find the BTU rating of your furnace, you can calculate how much propane it’s likely to burn per hour. For example:

30,000 BTU/hour ÷ 90,000 BTU/gallon = ⅓ gallon of propane/hour

You’ll want to make this calculation for all your propane-fueled appliances, so you’ll need to consider your RV refrigerator (see our post on how much propane an RV fridge uses), water heater, stove/oven, and any other propane-burning appliances you use in your rig.

You may then want to consider how long a particular size DOT cylinder tends to last (on average) and apply all of that information to your choice of what size might work best for use in your RV and for your particular needs.

How Long Does a Propane Cylinder Last?

You can also determine how many hours a given appliance is likely to run on a particular size propane tank by using the BTU capacity of each size propane tank. (You also need to know the size of each tank to know which would fit best in your available space.)

With this method, you’ll simply divide the tank’s BTU capacity by the BTU rating listed on your propane-fueled appliances.

Let’s look at the three sizes of portable propane tanks (DOT cylinders) available to see the dimensions of each one and the BTU capacity of each tank.

This should help you to determine which size tank would work best for your RV.

3 propane tank sizes and their capacities illustrated

Here you see the approximate dimensions of 20, 30, and 40-pound DOT propane cylinders, along with their respective BTU capacities.

Should you have the opportunity to connect to a 100-pound external propane tank (or if you have one permanently mounted on your RV), you’ll likely find the tank to be approximately 48″ tall/long and 14.5″ in diameter, with a capacity of 2,160,509 BTU.

Again, to determine how many hours an RV appliance will run on your full propane tank, divide your tank’s BTU capacity by the BTU rating listed on the appliance. If all you were planning to run was your furnace, we could do the following calculation for how long a 20-pound propane tank will last:

430,270 BTU capacity of the tank ÷ 30,000 BTU/hour consumption = 14.34 hours run time

How Much Do RV Propane Tanks Actually Weigh?

When we refer to a propane tank using pound measurements, that’s a rough estimation of how many pounds of propane the tank holds. These numbers, though, don’t include the tank’s weight. So, you’ll need to add the weight of the empty tank to the weight of the liquid propane to get the actual weight of the full tank.

For example, a 20-pound tank weighs 17 pounds empty. So, when it’s full, it’ll weigh 17 pounds + 20 pounds for a total of 37 pounds.

Likewise, a 30-pound tank weighs 25 pounds empty, so it’ll weigh 25 pounds + 30 pounds for a total of 55 pounds.

A 40-pound tank weighs 32 pounds empty, so when it’s full you’ll have a tank that weighs 72 pounds.

NOTE: You may have heard of the 80% fill limit on propane tanks (to leave room for expansion as temperatures climb), but that 80% maximum only applies to tanks whose size is rated in gallons. So, for example, a 250-gallon tank can only hold a maximum of 200 gallons. DOT tanks rated in pounds will hold that weight of propane (the room for expansion has already been factored in).

This is important to know, especially if you’ll be filling your tanks manually and replacing them in your RV. For instance, it’s possible that you’d prefer to carry two 20-pound tanks rather than a single 40-pound tank if you don’t want to have to handle a single tank weighing 72 pounds.

This is precisely why most RVers do carry two 20-pound tanks! In fact, most travel trailers, truck campers, and fifth wheels come standard with two 20-pound tanks.

Additional Thoughts on Propane Tanks

If you’re wondering how long propane tanks are good for, feel free to check out our post on that topic. For even more information, see our post entitled “RV Propane Tanks: What to Know for Safety and Comfort“.

If you’d like a better understanding of your RV propane system in general, check out that post.

Finally, have you ever questioned whether propane goes bad? Check out our post, “Does Propane Go Bad In an RV?” for the answer!

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mike loft

Monday 10th of April 2023

Hello, speaking of propane tanks..I've been going bonkers trying to figure out how, where to tee in to my on-board propane system to connect a new propane heater. I run a 2022 Rockwood 2511S. The last thing I want to do is ream a hole thru the door or wall from the barbeque quick connect. Or worse, bring the propane tank inside. Any advice? Much appreciated ~ Semper Fi. Mike


Monday 10th of April 2023

Hi Mike... good question. If you're talking about a small propane-powered heater like a Mr. Buddy that you plan to use indoors, you could tap into the propane line for any of the existing propane-powered appliances in your RV. Most likely, the line for the stovetop/oven will be the most accessible... though you'll likely need to remove some drawers or cabinet shelving to access it.

Just be sure to make secure, leak-proof connections so you don't have an issue with a propane leak down the road.

Brad Wartman

Friday 7th of April 2023

UPDATE: The price is $17/bottle (they come in a 2-pack for $34). My apologies for the error.

Why not refill disposable bottles (like Coleman)? First and foremost, disposable bottles are only meant to be used once. As a result, they are several differences between disposable and refillable bottles:

The walls of disposable bottles are thinner, leaving them to possible failure due to repeated expansion and contraction from repeatedly emptying & refilling the bottle. The pressure relief valve will give out over time due to repeated reuse...and the last thing you want to have happen is for that safety valve to fail and flood the inside of your camper with propane. The lack of a bleeder valve means that you can't meter the amount of liquid to the 80% "safe level" that allows for expansion. It's easy to overfill or underfill a bottle: if it's underfilled then the bottle won't last as long as expected... and if it's overfilled, taking the bottle someplace warmer or at a higher altitude may cause the safety valve to vent the excess pressure.

Lastly, transporting refilled disposable containers is a violation of DOT regulations. If caught the fine is up to $500K and 5 years in prison.

So, all in all, paying the extra for refillable bottles is well worth it.


Friday 7th of April 2023

Thanks for sharing all that, Brad. Good information.

Brad Wartman

Friday 7th of April 2023

If using 1 lb propane cylinders, consider buying a refillable one from Flame King. They're not cheap (I think they're going for ~$34/bottle on Amazon now) but when compared to buying disposable bottles for $5-8 they will pay for themselves quickly. I bought a set of 4 (plus a stand & fill valve) several years ago and the bottles have held up really well, not leaking once.

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