How long will Generator run on 20lb propane? {Updated 2020}

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The U.S. has experienced tumultuous weather the past few months. The interest in securing back up power has increased dramatically.

The news reports of tornadoes, hurricanes, and snow and ice storms that knocked power out for thousands of homes, inspire people to look for ways to avoid the inconveniences, and potential danger of not having powerwith the help of Generator run on 20 lb propane.

How long will a generator run on a 20 lb of Propane?

How long will a generator run continuously?

A natural gas generator will run as long as it is required to run. A natural gas line will always have the pressure it needs to operate. During a power outage the line will continue to have pressure.

A generator powered by natural gas will automatically turn itself on and run until the main power source is restored.A generator powered by propane will run until the propane supply is exhausted. Most propane tanks, either above or below ground, are 500 to 1,000 gallons.

Expect a propane powered generator to burn 2-3 gallons an hour. A 500-gallon tank will power your home continuously for a week. A 1,000-gallon tank will last for 2 weeks.

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Reaction from generator users who run it on 20 lb of propane-

  • I haven’t run my generator more than a few minutes as it has only recently been received. I do remember seeing 4 1/2 hours at approx. 1/2 load with a 20 lb tank.


I’ve stocked up with a few extra tanks and figure I’m all set as I’d probably run it for a few hours at a time to keep heat, hot water, and refrigerators available as needed.

How long will a generator run on a 20 lb of Propane?

The fact that propane doesn’t go bad was an influence in the decision to buy a LP powered generator.


  • ConsumerReports states that the average run time is 5 hours with various loads with 20lb tank. The more the load the less the run time and vice-versa. I have not had to use it yet so I cannot report from experience.


  • Ganarec lists this answer on their website as a spec sheet. As the generator can run on either 20 or 30 lb tanks I’ll provide both answers. Luckily I don’t have first hand data for this question.

à20 lbs = 4.75 hrs @ half load, 30 lbs = 7 hrs @ half load

Propane Tank Sizes

Before you can figure out what size tank you need, it’s important to know what sizes are available. Use our guide to figure out exactly which one of these you should buy for your particular home needs.

(20 Pound Tanks)

One of the most common residential propane tanks is the 20 lb. tank, which is the size of the tank you hook up to your propane gas grill or for other modest residential energy needs, like a fireplace.

20 lb. tanks are not used for home heating or anything else that is large scale, but the benefit is that you can purchase several tanks to have on hand for backup, and you can have them refilled at any propane retailer.

Final verdict

Propane is stored as a liquid under pressure and boils to produce a vapour that is drawn off at the top for the engine to use as the fuel.

First thing to keep in mind is that the estimate given by the manufacturer for the gasoline run time can be used for propane also because it is just that; an estimate or guess.

Propane only has about 10% less Btu content than gasoline gallon-to-gallon, so the estimate used by Yamaha for gasoline consumption will be very close for propane if not exact.

The biggest mistake most “experts” make in opinionating that a Generator run on 20 lbpropane or natural gas generator will lose power is based solely on these figures and not on any data they personally have.

When figuring power output of any fuel, the size of the engine has to be a significant factor of the total equation.  For instance, comparing a vehicle with a V8 engine to a generator with an 11hp generator attached can not be calculated the same.

The characteristics of the fuels and how they mix with air, how far the piston is in relation the gasoline float bowl effects the power derived from the fuel among many other things.  To presume that just  because the btu content is less, it is less powerful, is erroneous.

Propane generators are less efficient than gas generators, producing fewer BTUs per gallon of fuel.

However, propane is a cleaner-burning fuel than gasoline, making it better for both the environment and your generator. Gas does not burn cleanly, so it will release a higher number of toxins into the air and leave more carbon deposits in your generator’s engine.

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