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20 lb. BBQ Propane Tank – Usage & Refill Guide

Grill Propane Tank 101

The weather is finally breaking and the warm temperatures are being felt across the nation. Baseball season has officially begun and the sound of mowers cutting grass can be heard. All of these things point to the start of summer and thus, the start of BBQ season. Although the perfect hamburger recipe can be debated from here until eternity, there are a few definitive tips to save money while filling up that BBQ tank.


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A typical barbecue tank is also referred to as a 20-pounder. This is because the tank can hold approximately 20 pounds of propane. This equates to 4.7 gallons of propane. Propane weighs 4.24 pounds per gallon so now you get the 20 pound reference.

So, does a full tank weigh 20 pounds? No, because the tank itself has weight to it, too. That is called the “tare weight” which is the weight of an empty tank. Tanks have “T.W.” (tare weight) stamped on the collar of the tank. On average, the tare weight of a propane tank is about 17.2 pounds. Some might be 18 and some might be 16.6.

All in all, a completely full BBQ tank weighs approximately 37 to 38 pounds.

propane tank tare weight
The Tare Weight on this tank is 17.9 pounds.


An OPD valve is required on all grill bottle tanks. OPD is short for “Overfill Protection Device”. It is a safety feature that prevents the tanks from being overfilled. If you have a tank without an OPD, the company will not be able to fill your tank. If your tank has a fly wheel valve it’s the older style and cannot be filled. The OPD valves are more of a triangular shape (see below).

non-OPD tank

Above is a non OPD tank and will not be able to be filled.

OPD tank with good standing

Above is an example of an OPD valve on a good standing tank.


You will notice that there is date stamped on the collar of your propane tank. The Department of Transportation states that smaller propane tanks have a usable life of 12 years. After that, they will need to be refurbished. For example, if a tank has stamp 04 10 that means it will need to be replaced or refurbished on 05/2022. Most local propane marketers can refurbish out-of-date propane tanks.

To Refill or Exchange

In terms of most value for your dollar, I would recommend having your propane tank filled by a local company versus a tank exchange at a gas station or big box store. The national chains often fill their BBQ tanks with only 15 pounds of propane. This means that you are truly only receiving 3.5 gallons (15 lbs of propane = 3.5 gallons of propane). Your local garden center or propane marketer normally fill your propane tank with 20 lbs of propane or 4.7 gallons.
Some people might ask what the big deal is, because it’s only a difference of 1.2 gallons. However, when it comes to grilling, 1.2 gallon of propane equals about four to five hours of extra grilling time. I could show the calculation of this, but it bore even Steven Hawking.

In addition, the cost at one of these exchanges are usually $20-22 per tank. If you look around many local propane marketers offer deals in the summer time for tank exchanges. The deals normally range from $12-$15 per bottle exchange.

The per gallon comparison looks like this:

Big Box Store tank exchange for $22 equates to $6.28 per gallon of propane.
Local Fill station for $12 equates to $2.55 per gallon of propane.

Knowing When To Refill Your Tank

The simple answer for knowing exactly when you need to refill your tank is to actually weigh it. Use the Tare Weight as your base line and the difference is the amount of propane left.

For example:
TW=17 and the total weight of the tank is 25 lbs. This means that you have 8 lbs of propane (25 lbs – 7 lbs = 8 lbs) or 1.9 gallon left. Note that 1.9 gallon equals about 7 hours or so of grill time.

It’s always fun to leave in the middle of a BBQ with your tank under your arm and go weigh yourself, right? It’s a really cool party move. False.

The best option is to have a backup tank and just swap it out. Also, if you bring a half full tank to get filled you are charged a flat fee and not a per gallon fee. So, it’s also better to run completely out and then get it filled. Having a backup tank allows you to do this.

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