20 lb. BBQ Propane Tank – Usage & Refill Guide

non-OPD tank

Table of Contents

Grill 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 and tailgating 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.

The Facts:


A typical barbecue tank is also referred to as a 20-pounder. This is because these smaller tanks 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 20-lb propane 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.

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

The Tare Weight on this tank is 17.9 pounds.


An OPD valve is one of the propane tank parts 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 above 80% of their full capacity. The liquid propane capacity, just for reference, is the same as the water capacity. If you have a tank without an OPD, the company will not be able to fill your tank – safety measure. If your tank has a flywheel valve it’s the older style and cannot be filled. The OPD valves are more of a triangular shape (see below).

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

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


You will notice that there is a date stamped on the collar of your propane tank. The Department of Transportation states that smaller portable 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 Most local propane marketers can refurbish out-of-date propane tanks.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 at a tank exchange companies at a gas station or big box store. On the question of how much propane you get – the national chains and tank exchange places often fill their BBQ tanks with only 15 pounds of liquid 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 gets your tanks filled 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 gallons of propane equals about four to five hours of extra grilling time.

In addition, the cost at one of these exchanges with a propane company is usually $20-22 per brand-new tank. If you look around many local propane marketers offer deals in the summertime 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 weigh it or use a simple hot-water trick. Use the Tare Weight as your baseline 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 gallons left. Note that 1.9 gallons 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, second 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 old tank allows you to do this.

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Ryan McCabe

Ryan McCabe

Ryan is a home and small business energy expert, having overseen retail propane, heating oil, and HVAC services companies. On ComparePropane, Ryan writes about things that people should know when shopping for or using propane in their homes and businesses. 

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