Can’t wait to get going in your RV, but stuck on what propane tanks to get?

The world of propane can be a little bit niche, but don’t worry. It’s easy to simplify – which is exactly what this guide’s here to do.

So what’s the best propane tank size for an RV?

RV’s use propane tanks either 20lb or 33lb in size. Most RV users choose the smaller 20lb propane tank because of their availability. However, on long haul trips an RV using larger 33-lb propane tanks can go longer between refilling. See the full comparison below for more detail on RV tank sizes.

Since there are only two types of propane tanks – built-in and portable – let’s cover each one seperately.

Built-in RV Propane Tank Sizes

First are the more permanent tanks that are designed into the RV itself. These are called ‘ASME’ tanks, because they’re certified by the American Society of Mechanical Engineers.

Their sizes range from small 20-lb tanks found in small RV’s, all the way up to 100-lb tanks in the largest Class A Motorhomes.

RV ASME Propane Tank

A typical built-in RV Tank. Source: WorthingtonIndustries

These tanks are simply attached to the frame of the RV using the brackets you can see in the image above. The connections are all entirely secure, and the tank is refilled just like the petrol tank in your car.

Because these tanks are so protected, secure, and always professionally fitted – they don’t need to be recertified! Unlike portable tanks, which must be checked for wear and tear.

The tanks can range in length from 2-feet all the way up to 12! And their diameter from 10 to 30 inches. They also almost always have a gauge to tell you just how much propane you have left in your tank (unlike portable containers).

Since they come attached to your RV, there’s not much discussion to be had in the way of choice. Typically the RV manufacturer will have made sure it’s big enough to suit your motorhome. If you are given the choice of sizes, take as large a tank as your budget allows. The greater the capacity, the less money, time, and hassle you need to spend on refills.

Worried about refilling a built-in tank, or where to fill it up? Check out the refilling section below, or our full guide to finding propane for your RV.

Portable RV Propane Tanks

Portable propane tanks for an RV are simply the same kind that we use to power grills for those summer barbecues. They’re called ‘DOT’ tanks because they’re certified by the Department of Transportation.

These are typically used with trailers, fifth wheels, and smaller motorhomes. While they’re much smaller than a typical built-in tank, they’re much easier to refill (or exchange) and you can increase your capacity by carrying multiple tanks around.

The main decision is which of the two most common sizes to get – 20lb, or 33lb tanks?

20lb (5-Gal) vs 33 lb (7-Gal) Propane Tanks for an RV

20lb vs 33lb Portable Propane Tank Appliance Analysts

Comparison Issue20lb (5-Gal) Tank33lb (7-Gal) Tank




Less common
TanksExchange Often

Keep Your Own




Easy to have 4 tanks

Typically 2 at a time

These are the same tanks you’d use in your barbecue, and for this reason are seen by ‘dirty’ as some. Many prefer to have their own tanks that they keep and look after, rather than a frequently used and exchanged cyclinder.

But you can’t argue with convenience. Being able to walk into almost any supermarket and leave with a full tank of gas isn’t to be underrated. Refilling a 30-lb tank means planning where to stop, or spending more time hunting around for the right type of gas station.

Keeping your own tanks also means needing to recertify them when they are over 12 years old. (And every 5 years after that). Not necessary when exchanging tanks.

20-lb tanks are also easier to always have backups. Since they’re much lighter, it’s easy to carry around 4 tanks. Two to use, and two as replacements. Then you simply swap out the empty ones whenever it’s convenient.

Some may argue that you get more in a 30lb container setup, but not if you have double the number of small tanks! Instead of using up a 7-gal tank then looking for a refill, you’re using up 10-gallons worth of small tanks before you look for an (easier to find) exchange.

My opinion: Get four 20-lb cylinders. As long as you’re not too fussed about using exchanged tanks, the benefits well outweigh the cons.

How To Estimate Propane Use In An RV

We can find a rough approximate of how much propane your RV will use/require based on the furnace you’ll have and the appliances you’ll use.

  • Furnace: An RV furnace can use anywhere between 20,000 and 40,000 BTU – depending on it’s size. You can find this out simply from your RV manual, or by looking at the furnace itself.
  • Ranges: Typically, a range will use around 10,000 BTU an hour, when on. Again, you can find this out simply by checking the range.
  • Fridges: Most RV’s use a propane fridge – these can vary, but tend to use around 1,500 BTU per hour. This doesn’t seem like much, but adds up over time since it’s always on.
  • grills: If you’re also using your propane to power grills, expect a medium grill to use around 8,000 BTU an hour, while a larger one will use up to 10,000 BTU.

Simply combine your furnace with the appliances you expect to use throughout the day, and you can approximate your heating requirement.

For example, a standard RV furnace on for 2 hours a day (30×2), plus a range on for 1 hour a day (1×10), plus a fridge that’s always on (1.5×24) gives a demand of around 106,000 BTU per day.


With your demand, we can find out how much propane you’ll use daily.

Propane produces around 91,500 BTU of heat per gallon (or 21,500 BTU per pound).

This means that a 5-gallon cylinder, filled to 4 gallons (80% capacity), will supply you for ([4 x 91.5]/106) = around 3.5 days. 

Getting The Most Out Of Your Propane

While propane’s not the greatest expense the world, it’s always good to get the most out of your research. Not to mention saving time, money, and helping the environment in the process!

Here’s a few tips to lower your usage:

  1. Make sure to drive with propane off. If you’re using a propane fridge, it’s almost definitely got a setting to be powered by DC electricity. Try to use that when you’re driving – it’s more efficient, and safer, too. When moving something could happen to the propane line, causing gas to escape and build up.
  2. Insulate! Any homeowner who’s done some DIY can tell you how effective insulation is. Make sure your windows are sealed, and the RV is an insulated as reasonably possible. It can mean a massive reduction in gas station trips.
  3. Find the cheapest prices. Always call around and check the cheapest price available nearby. We’ve got a big part on making the most of this in our guide to finding propane for your RV.
  4. Conserve your supply. If you may be running low, consider throwing on a bigger jumper rather than turning up the furnace. Equally, try to avoid using the oven in the range – a quick stir fry or a cold dish can use just a fraction of the fuel.

RV Propane Tank Holders

Unlike using a propane tank in a garage or patio, RV propane heaters need to be mounted.

At least, portable DOT tanks do. As mentioned above – ASME tanks are built in and come with great peace of mind since you don’t need to install them or worry about them being exposed.

If your RV doesn’t come with an ASME tank, it likely comes with a propane tank holder. These tank holders should accommodate multiple propane tank sizes for your RV, but may be specifically for (or best for) one size in particular. This should be stated in your manual, on the holder itself.

Most holders are capable of holding two cylinders. These put extra emphasis on the importance on the larger 33-lb propane tanks on an RV. However, some can hold more cylinders, or are capable of easily storing spare tanks. In which case, 20-lb propane tanks are just as good an option.

Any good propane tank holder on an RV should be made of powder-coated steel or aluminum. Make sure to check that it’s still in good condition, especially at the connections and anywhere that could rub against the propane tank.


Propane tanks and their uses can be one of those things that are just part-and-parcel of being an RV owner.

While they can be intimidating at first, it’s all relatively simple once you’ve wrapped your head around it. Once you understand something, it becomes a lot less worry-inducing / scary.

I hope this guide’s helped clear things up for you. If it has, please consider supporting us by checking out some other articles, or joining our mailing list!

Thanks for reading – and have a great day 🙂