How Long Does a 20lb Propane Tank Last? [Usage Guide]

I love everything about camping but I must admit that preparing for a trip is not my favorite task. When preparing for a camping trip, I always make sure I have enough propane so I can cook and have enough hot water for showers in my RV.

Understanding how long a propane tank lasts can help you prepare properly and will ensure you don't run out at the worst possible time.

A 20lb propane tank lasts 3 hours when running an RV furnace and 1 week for a water heater. A stove lasts between 13 and 15 hours, a medium-sized grill between 18 and 20 hours and a large grill 10 hours. 

Depending on the setting and BTU rating, a space heater lasts between 30 and 115 hours. A 20lb propane tank can run an RV refrigerator for 30 days continuously or 90 if you only run it 8 hours a day.

If you use a 20lb propane tank when camping, understanding how long it will last with your camping equipment can ensure you don’t run out of fuel. 

How Long Do 20lb Propane Tanks Last?

A 20lb propane tank holds 4.5 gallons of propane and the table below shows how long it will last on various RV and camping appliances: 

How Long 1 x 20lb Propane Tank Will Last
Furnace3 hours
Water heater1 week
Space heater30 to 115 hours (depending on the heater’s BTU rating and heater setting used)
Refrigerator30 days if continuously running90 days if only running 8 hours a day
Single Burner Stove
(7,500-10,000 BTUs)
40 to 55 hours (1.6 to 2.3 days)
Multi Burner Stove
(30,000 BTUs)
13 to 15 hours
Medium-sized grill18 to 20 hours
Large grill10 hours

Do you also use 1lb or 5lb propane tanks? If so, this useful guide explains how long a 1lb propane tank lasts, and this article discusses 5lb tanks

How To Calculate Your Propane Tank’s Burn Rate

The table above gives general estimates of how long a 20lb propane tank should last with various appliances. However, if you want a more accurate burn or consumption rate, you’ll need to use an accurate formula. 

Here’s how to calculate your propane tank’s consumption rate: 

1. One gallon of propane has a BTU (British Thermal Unit) heat energy rating of 91,502. To calculate how long a gallon will last on your appliance, you’ll need the appliance’s BTU rating per hour (a 20lb propane tank has a BTU rating of 420,000). 

2. Divide 91,502 by your appliance’s hourly BTU rating. The higher the rating, the more propane it will use. 

3. This will tell you how many hours a gallon of propane will last on your appliance. 

4. If you have a full propane tank (4.5 gallons), you should then multiply the number of hours by 4.5. 

For example:

A Coleman 2-burner propane stove puts out around 20,000 BTUs when both burners are on full blast. Less if the burners are turned down to a simmer and half that if you're only using 1 burner on full blast.

This means it'll take roughly 4 hours 34 minutes to burn through 1 gallon of propane with both burners going on full blast (91,502/20,000 = 4.57) or over 9 hours with just one burner going.

Given a 20 lb propane tank has 4.5 gallons of fuel this means it'll take roughly 20 hours 35 minutes (4.57 hours x 4.5 gallons = 20.59 hours) to go through the entire tank with both burners on full blast or around 41 hours with only 1 burner going.

What Affects How Long a 20lb Propane Tank Will Last? 

Aside from using the table provided above and calculating the propane consumption rate based on your appliance’s BTU rating, other factors can influence how long your propane tank will last: 

  • BTU rating of the appliance (the amount of energy it uses per hour)
  • How often and efficiently you use the appliance 
  • Condition of the tank, valve and fuel line 
  • Fuel quality

How To Check How Much Propane You Have Left

Below are 3 effective ways to check how much propane you have left in your tank: 

Use a Propane Tank Scale

This is the most accurate method and it’s also convenient because propane scales are compact and inexpensive. 

Simply attach it to the top of your propane tank, lift it up and you’ll get an accurate reading. 

Grill Gauge Propane Scale is a great model to consider and is lightweight enough to take camping. 

Grill Gauge Original Propane Tank Scale

Quickly and accurately check your tank's propane and see how much you have left. Works for 20 lb and 15 lb exchange tanks. Just lift it and you'll see exactly how much propane you have left.

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Use an Inline Fuel Level Indicator

If you like to check your propane levels as you use your camping appliances, an inline fuel indicator is probably your best bet. These propane indicators are installed in the fuel line and give you accurate propane level readings at a single glance. 

For example, Flame King Propane Tanke Gauge Level Indicator from Amazon is quick to install and is also compatible with other size propane tanks. 

Flame King Propane Tank Gauge Level Indicator

Grill, camp, and heat with ease without the worry of running out of propane. Meter will show when you're running low so you never run out. Emergency flow control detects gas leaks and restricts flow ensuring your safety and peace of mind

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You can also get this propane pressure gauge and refill adapter hose from Amazon. Not only can you measure your propane tank and see how full it is but you can also use it to refill 1 lb propane tanks. Learn how to refill 1 lb propane tanks.

Pressure Gauge 36" Propane Refill Adapter Hose (1 lb Propane Gas Adapter)

Check the pressure of propane tanks from 1 lb all the way up to 20 lbs. Can also be used to refill propane tanks

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Use the Boiling Water Method

Using boiling water isn’t the most accurate way to check how much propane you have left but it will work in a fix. 

Boil 2 or 3 cups of water and position your propane tank upright (this method won’t work if it’s on its side or at an angle).

Pour the boiling water on the side of the tank and use your hand to feel where the tank becomes cool – this is roughly how much propane you have left in your tank.