To begin to figure out how long your propane tank will last first we must consider the size of your propane tank. The average grills propane tank is a 20 pound tank that is supposed to supply 22,000 BTU’s per pound. A typical tank holds 20 pounds of propane when full.
So if we do the math here it’s 20 X 22,000 = 440,000 BTU’s for a full tank.
Now if you divide 440,000 by the BTU’s of your grill.
Since math is hard, here is a ballpark breakdown for you
Small grill around 25,000 btu’s – Giving us 17.6 hours
Mid size Grill around 40,000 btu’s – Giving us 11 hours
Large Grills around 60,000 btu’s – Giving us 7.3 hours
To find the exact BTU’s of your grill refer to the manufacturer’s website they are typically listed there.
Don’t know what a BTU is? The British thermal unit (Btu or BTU) is a traditional unit of heat; it is defined as the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit. Per Wikipedia
Since nobody cooks on high heat all the time (I’ll typically only have 2 burners on neither one on high) you will have to guestimate the percentage of gas you typically use for more accurate calculations. I really wish that was the end of this, but it’s not.
A couple of more things to consider:
You will never get that last few of pounds of propane to deliver enough heat to your grill to cook anything.
I have found that a propane tank lasts longer in the summer months than during our cold winters, so cut approximately 15 to 20% off of the life expectancy of your propane if you grill during below freezing weather. This could be due to contraction of the gas in the cold or just because you need to cook at higher temperatures.
If you purchase your propane from a propane exchange it only has 15 pounds of propane or 330,000 btu’s.
More on the subject: How to tell if how much propane is left in your tank.
About the author: Mike is the owner of 4thegrill.com, a Certified Food Safety Professional, KCBS member and apparently now an amateur mathematician.
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