How Long Does A Propane Tank Last?

The only thing worse than not having propane at all is having a propane tank that gets exhausted while you’re in the middle of using it! No one wants to end up with a half-grilled dinner. That’s why it’s necessary to know how long a propane tank lasts — so that you can refill it at the appropriate time and avoid unwelcome surprises.

How long a propane tank lasts depends on the size of the tank and how often you use it. Homeowners who use 20-pound propane tanks and medium-sized grills should expect about 18-20 hours of grilling on high heat, or less on larger grills. It’s cheap and easy to keep a spare full tank on hand.

Since these are merely estimates, you should also know how to calculate your tank’s burn rate. That way, you can quickly determine when you might need to refill your propane tank. Let’s look at how this calculation works and how often you should refill a tank.

How Many Hours Do Propane Tanks Last?

Clean Propane Tank

Before we go into the details, the simple answer to this question is that it depends on several factors. That means there’s no definitive number of hours that a propane tank lasts. Still, it’s good to have an idea of how long it might last to avoid running out of propane fuel when you least expect it.

To break it down for you, small propane tanks, otherwise called DOT tanks, can weigh anywhere between 20 and 100 pounds. How long a DOT tank lasts depends on how often you use your furnace and heater, and the size of your grill.

Generally, a medium-sized grill set to high heat will consume approximately 2 pounds of fuel per meal. Based on this, a 20-pound propane tank like this one from Flame King (on Amazon) should be able to cook for 18-20 hours on medium-sized grill. The same tank will only last for about 10 hours on a larger grill. 

How Do You Calculate Your Burn Rate?

Since different factors contribute to how long a propane tank lasts, it’s better to know how to make customized calculations based on the propane tank you own. Follow these steps to do that:

  1. Find out how much your tank weighs (usually called the tare weight). You can find this on the body of the tank.
  2. Find out the total weight of your propane tank (with propane inside) and subtract the tare weight from it.
  3. Divide your tank’s total weight by 4.24. 4.24 pounds of propane equals one gallon, so this makes it easier to convert to gallons in the future.
  4. If your propane grill burns at 60,000 BTU per hour, this means that one gallon of propane will burn for 1.53 hours. The burn rate of the appliance is therefore 1.53 hours per gallon of propane (92,000 BTUs/60,000 = 1.53 hours).
  5. Determine how many hours of propane you have left by dividing the total gallons of your tank by your appliance’s hourly burn rate.
  6. By repeating this procedure, you can observe how several appliances burn fuel with different BTU rates.

Due to the complexity of this calculation, you might need a professional to help you out.

Propane Usage Statistics

As we’ve mentioned, how often you use your propane and what exactly you use it for will determine how long it will last. Below are a few of the ways you can use your propane and how long it’ll possibly last:

  • Grilling: 20-pound propane tanks are designed to handle modest tasks, such as preparing individual meals. We’ve also mentioned that you should be able to cook for 18-20 hours on a medium-sized grill, and about 10 on a larger one.  In general, you’ll burn roughly one to two pounds of fuel per meal when using a medium-size grill on high heat. So, you can expect to grill about eight times per tank.
  • Furnaces: The British Thermal Unit, or BTU, is an industry-standard measurement for determining how efficient a home appliance is at heating. Each gallon of propane corresponds to 92,000 BTUs. The average furnace runs on about 100,000 BTUs. That means a typical home furnace burns approximately one gallon of propane each hour. Based on this, you can expect your furnace to burn between 500 and 1,200 gallons of propane annually, depending on how frequently you use it.
  • Water Heaters: You will use more hot water when you have multiple bathrooms in your home, as well as when you have guests in your home. On average, a typical home uses approximately 1.5 gallons of propane per day to heat hot water. In the average household, propane hot water consumption is about 200-300 gallons each year. As a rule of thumb, homeowners will heat and cook in their homes with an average of 2.5 500-gallon propane tanks per year.

How Often Does a Propane Tank Need to Be Filled?

You wouldn’t want to run out of fuel while you’re in the middle of using it for something important, so you should always confirm that your propane level isn’t low before you start using it. If you recently filled your tank and have only done a few things with it, then you might not need to worry about checking.

If you’ve used it for quite a while, you should check.

There are different ways to find out how much propane is left in your tank, but a common method is to pour hot water from a cup down the side of the tank and feel it. The propane area will be cold to the touch. A cold spot indicates where your propane level begins in the tank.

You can also find out how much propane is left by following the calculation steps we explained above. Once you discover that your propane level is anywhere under 20%, it’s time to refill it.

Can You Refill a Half-Full Propane Tank?

Two 20 pound rv propane tanks

Yes, you can refill a half-full propane tank. No law states that your tank must be empty before you refill it. You can visit a legitimate refill station and have it filled to its original weight or volume using vented propane, then pay for the propane used.

Some stations charge for a complete refill, but there are lawsuits against that, so confirm that you aren’t getting cheated.

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