Which RV Propane Tank Size Do I Need?

Your stove. Your furnace. Your refrigerator. Your RV's LP (Liquid Propane) tank does a lot for you by running your appliances and keeping your rig cozy and functional. You already know this, but what you may not know is what size RV tanks are available, or what size you need.

Below, we'll go over the basics of RV propane tanks and help you choose the right size tank for your trailer, motorhome, or fifth wheel camper.

Types of RV Propane Tanks

There are two types of propane tanks: ASME tanks, which are permanently mounted and are typically seen on motorhomes, and DOT cylinders, which can be removed and are typically used on travel trailers and fifth wheels.

What does this mean for you? If you have an ASME tank, not much. It's built into your motorhome frame, and it's not going anywhere. Just inspect it regularly to make sure it's not rusting or leaking, refill it when it's low, and replace it if it's ever in bad condition.

If you have a DOT cylinder, however, you have the option to change out your tanks and use a different size. You also have the responsibility of making sure your tanks are within their expiration date and getting them recertified when necessary.

ASME Tanks

DOT Cylinders

Cannot be removed

Removable

Built into motorhomes

Usually seen on travel trailers and fifth wheels; mounted on trailer exterior, such as in storage compartments or on trailer tongues

Generally larger (up to about 100 lbs)

Generally smaller (usually 20, 30, or 40 lbs)

Do not need to be recertified

Must be recertified after 10 years, then every 5 years after that by a propane retailer

Must refill at propane service station

May refill or exchange, depending on tank size

Approved by the American Society of Mechanical Engineers (ASME)

Approved by the Department of Transportation (DOT)

RV Propane Tank Sizes

When it comes to built-in ASME tanks, you don't get much say in the tank size your motorhome comes with. Fortunately, these tanks are typically quite large (a large Class A RV may have an 80 - 100 lb tank capacity).

With DOT cylinders, you do have several tank size options. Your camper most likely came with a propane tank or two, but you can always replace them with a different tank size. The most common propane tank sizes used in RVs are 20 lbs, 30 lbs, and (less commonly) 40 lbs. So, what size tank will be best for you, and how many of them do you need? It depends.

There are three main considerations when it comes to deciding on a propane tank size for your camper: how long your propane tanks last, tank weight, and whether you'll refill or exchange your tanks.

How Long Do RV Propane Tanks Last?

As you might expect, the size of your camper and the frequency with which you use propane play a big role in how long your propane tanks last and, by extension, which size propane tank you need.

If you tow a small travel trailer or truck camper, you may only need a single 20-lb tank (these are the same propane tanks you use for your BBQ pit). A large fifth wheel, however, may call for two 30-lb tanks. If you camp for very long periods of time (especially in the cold) and your camper can handle the extra weight, you may even consider 40-lb tanks.

The temperature and time of year also matters. If you need to run your heater for a cool fall/winter camping trip, you'll probably use more propane. If you're camping in the middle of summer and don't need your heater, you can probably get by with less.

The best way to figure out how much propane you use per trip is to go camping. Use your furnace, water heater, fridge, grill, etc. the way you normally would. Use the tanks that came with your RV, and pay attention to how often they need refilling.

To give a rough estimate, two 20-lb tanks are probably enough for a week of warm-weather camping, depending how much hot water you use and how much propane cooking you do. Two 30-lb tanks are usually more than enough in this situation. Two 40-lb tanks can most likely get you through a week or two of camping in cold weather.

A single 20-lb or 30-lb tank is usually enough for an extended weekend in warm weather, but again, it depends on your showering and cooking habits. Daily propane cooking and showers for a family of 4 or 5 may be hard on a 20-lb tank over a 3 or 4 day extended weekend, but 2 people using propane moderately will usually be fine.

If you want a more specific idea of how long your propane tanks will last, you can also use math to figure it out based on how many gallons of propane you have and how much gas your appliances use. To give you an idea, here's what each tank weight translates to in gallons:

20-lb tank: about 4.6 gallons
30-lb tank: about 7 gallons
40-lb tank: about 9.4 gallons

How Long Do Propane Tanks Last Infographic

Each gallon of propane is about 91,502 BTUs (British thermal units). If you know the BTU rating of your appliances, you can estimate how long you can run each appliance.

For instance, let's say your RV furnace runs at 30,000 BTUs per hour. One gallon of propane will keep your furnace running for about 3 hours. If you have a 20-lb tank (4.6 gallons), this means you'll be able to run your furnace for about 13.8 hours on a full tank.

(91,502 BTUS) / (30,000 BTUs per hour) = (about 3 hours furnace run time per gallon)

(4.6 gallons) X (3 hours per gallon) = (about 13.8 hours furnace run time per 20-lb tank)

Of course, you're probably running other propane appliances too, and you're probably not running any of them for 24 hours a day. If you can figure out how much propane each of your appliances uses and how long you typically run them, you can get a rough estimate of how long your propane tank(s) will last. If a single 20-lb tank isn't enough, consider upgrading to dual tanks (or even more), or switch to larger tanks.

Tank Weight

It's no secret that in the RV world, weight counts. More propane tanks obviously mean more weight to tow around, so you should always factor this into your weight calculations. Also consider that you'll be handling these tanks yourself. It may be easier to pick up and refill three 20-lb tanks than it would two 30-lb tanks.

Keep in mind that a 20-lb propane tank simply holds 20 lbs worth of propane — 20 lbs is not the actual weight of the full tank. Always add the weight of the tank itself to the weight of the propane to get the full weight of a filled propane tank.

20-lb tank — full weight 37 lbs (17 lbs empty)
30-lb tank — full weight 55 lbs (25 lbs empty)
40-lb tank — full weight 72 lbs (32 lbs empty)

Some RVers prefer using multiple smaller tanks (such as four 20-lb tanks — two to use and two as a backup) simply because they're much easier to move. (Also keep in mind that if you buy a larger tank, you'll need to purchase a larger propane tank cover for the front of your RV.)

Exchanging vs Refilling Tanks

You have two options when your propane tanks run low: you can exchange your tank for a full one, or you can refill the one you've got. Exchange services are typically offered for a fee at hardware stores and large retailers like Walmart, and even on site at some campsites.

If you plan on exchanging your tanks, stick with the 20-lb size. 20-lb tanks are the most common type found at exchange locations (as mentioned, these are the same tanks people use to BBQ). Most places don't have 30-lb or 40-lb tanks available for exchange.

If you plan to refill your tanks, you can choose any tank size. Check your RV dealership, campground, local propane dealer, and U-Haul locations for propane-filling services (try searching "refill RV propane near me" in your web browser). Some RV parks also offer refill services right at your campsite!

So, should you exchange your tanks and limit yourself to 20-lb tanks? Or should you just refill as needed and use whatever size tank you want? It depends on your preference; there are benefits and drawbacks to each.

Exchanging Tanks

PROS

Highly convenient - can typically do this at any Walmart or hardware store
Can trade out your nearly expired tank for a new one

CONS

Typically costs more than refilling
May not receive a completely filled tank in exchange
May end up trading your newer tank for an older one in worse condition
You don't know how well the tank you receive was cared for by the previous owner
Limited to 20-lb tanks in most exchange locations

Refilling Tanks

PROS

Typically costs less than exchanging
More control over the amount of propane in your tank
Can keep your own tank in great condition and use it for years

CONS

May not be as easy to find a refilling location as it is an exchange location
DOT tanks must be recertified every 10 years, since you'll be using the same tank

There's no one right answer when it comes to choosing your propane tank size. If you camp for long periods of time using propane, have a large camper, and can afford the extra weight, it may be worth using 30-lb or even 40-lb tanks. If you have a smaller camper or plan to exchange your tanks, 20-lb tanks are lighter and more convenient.

Still have questions?

Give our experts a call at 800-298-8924, or contact us online. We're happy to assist any way we can!

About the Author

As a content writer for etrailer, I might spend my morning loading and unloading a bike on five different bike racks to figure out which is easiest to use. I might be in the parking lot, taking pictures of an impressive RV battery setup our techs came across in the shop and discussing the benefits of the setup with the owner. I might spend an afternoon in a manufacturer training class for some hands-on experience with new products, and then sit down to assemble all this information into a coherent article.

At etrailer, one of our core values is that we are always learning, and I learn something new every day. I start each morning with the goal in mind of taking all of this information and figuring out the best way to answer the questions people ask us (and the ones they don’t know to ask yet), and helping people get the solutions they need to make their lives easier, safer, and more fun. I’m a DIYer at heart, so it brings me great joy to help a fellow DIYer find what they’re looking for, whether that’s a product, an answer, or a community.

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Written by: Amber S.

Updated on: 2/2/2021

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