How Much Propane Does a Generator Use – Let’s Find Out

How Much Propane Does a Generator Use - Let's Calculate

propane for generator

Out of all the modern backup power sources, generators are still everyone’s first choice. Not only can they run on a wide range of available fuels, but a portable generator can also power all the required devices simultaneously. 

So, be it your refrigerator, heater, air conditioner, TV set, lamp, etc., you need not compromise on anything!

The only requirement is sufficient propane (or any fuel) on standby. 

But how much propane do I need? How many gallons of propane does a generator use in a day?

A typical propane-powered generator will consume roughly 2-3 gallons per hour. Depending on your tank’s capacity and hours of usage, you can calculate the approx. propane requirement for the day, week, or month. 

Read on as I answer all these questions in detail. 

How Much Propane Does A Generator Use – Entire Math 

Let’s now calculate how much propane a generator uses in an hour or day. 

Note: All the following calculations and figures aren’t exact but approximate. An example is also discussed to calculate gallons of propane required by a 20kWh generator. 

Some basic figures:

  • Liquid propane weighs 4.2 lbs/pounds per gallon 
  • The fuel value of propane is 91,500 BTU 
  • 1 HP of mechanical energy requires 10,000 BTU of fuel in an hour 

We’ll use the above figures in the following calculations. 

  • Find out how much horsepower you need to run your electrical appliance. 

Formula: Horsepower = (Watts/ 1000)*2 

  • Represent the above value in horsepower in terms of BTU. 

Formula: BTU = Horsepower*10,000 (in 1 hour)

  • Calculate the gallons of propane required. 

Formula: BTU/91,500 

Consider this example. 

Suppose the generator capacity is 20kWh. In horsepower, it’d be 40 HP, as per the above formula. In BTU, it’d translate to 400,000 BTU

To calculate the gallons of propane, you need to divide this 400,000 BTU by the current fuel value of propane, i.e., 91,500 BTU. Or 4.37 gallons

So, 4.37 gallons of propane will be required to power a 20kWh generator. 

Note: A 20-pound propane tank contains 4.6 gallons of propane.

As you can see, a 20-pound tank has an insufficient amount of propane to power your house for the whole day. Thus, I suggest keeping enough spare propane handy during outages. 

Related: What is an Inverter Generator? Answers & Best Models

Factors That Affect How Much Propane A Generator Will Use In A Day 

Now that we’ve calculated how much propane a generator uses in a day, it’s important to know what factors govern its daily consumption. 

  • Size Of Your Property 

The bigger your property, the more propane your generator will use to power it during outages. This is because the generator will need to power up more devices than usual over a large area—for example, heaters in winter. 

  • Power Requirements Of Appliances 

The power your electrical appliances use also influences the gallons of propane you’d require to power them up.  

For example, a typical home refrigerator uses 350-780 watts of power. Talking about a dehumidifier, a portable model is typically rated 30-50 watts. If it’s a whole-house dehumidifier, it’ll use an average of 250 watts per hour. 

So, the power consumption of your electrical devices is also important when calculating how many gallons of propane your generator will use. 

  • Power Generating Capacity Of Your Generator

The next factor is the power-generating capacity of your generator. 

An average American home consumes ​​10,715 kilowatt-hours (kWh) in a year. Even if you lose power 10% of the time in a year, it translates to 1071.5 kWh, which is generated by approx. 535.75 horsepower. 

As one horsepower consumes 10,000 BTUs of mechanical energy, it’ll require over 5,37,500 BTUs or 58 gallons of propane to power your home for just 10% of the time in a year. 

  • Number Of Hours Without Power 

A generator of 20kW capacity uses anything between 2-3 gallons of propane per hour (again, an estimate). Thus, the more hours you spend without power and on the generator, the more gallons of propane are required. 

Note: Other factors include your generator’s efficiency, tank capacity, outside conditions (winter/summer), budget, etc. 

Related: Best Whole House Generator – 5 top Picks For All House Sizes

Why Should You Run A Generator On Propane?

Generators run on various fuels, for example, natural gas, gasoline, diesel, propane, etc. Among all these, efficiently burning and “cleaner” propane is a widely used fuel, be it for commercial or domestic generators. 

Some of the critical benefits of using propane as fuel are as follows. 

  • Propane Is Readily Available 

One of the main advantages of a propane-powered generator is easy access to propane. Unlike diesel or gas, which can only be refueled from fuel stations, you can store propane at your home in cylinders or tanks for quick access as the fuel runs out.  

Thus, no rushing to the refueling stations!

  • It’s A “Cleaner Fuel” 

Besides being a non-toxic fuel, propane is also a great choice to reduce your environmental carbon footprint. It’s listed as a “cleaner fuel” in the 1970 Clean Air Act and Energy Policy.

Propane has:

  • 20% less nitrogen
  • Up to 20% less greenhouse gas emissions 
  • 60% less carbon monoxide (CM)

Note: You can also install propane tanks underground in your backyard without worrying about any soil contamination. 

  • Propane Is Cheap 

Who doesn’t want to save a few bucks when it’s possible? 

As 1 cubic foot of propane encompasses 2,516 BTUs, it’s more than 2x what natural gas, another popular fuel, offers. FYI, 1 cubic foot of natural gas has 1,030 BTUs.  

Hence, propane produces more than 2x the energy of natural gas, thus cutting fuel costs.

  • Propane Is Odorless 

If you just hate the awful smell of gasoline, propane is for you as it’s odorless. Plus, it evaporates quickly. 

Note: Since liquid propane can leak if not stored properly, some companies add ethyl mercaptan to produce a faint odor to understand the exact point of a leak from the cylinder or tank. 

  • Propane Has An Indefinite Shelf Life 

Did you know that propane can last for an indefinite period? Thus, it’s the most stable and resilient-friendly fuel around. 

In other words, propane doesn’t lose its potency over time and degrade. FYI, the shelf life of diesel is 1 year, and for gasoline, it’s just 3-6 months. 

Related: Propane vs Gas Generator: Which is Right For You?

How Much Propane Does A Generator Use FAQs

  • How Much Propane Does An 18kw Generator Use?

Ans: An 18kw generation would use up to 3.9 gallons of propane per hour. Multiply this by the total number of hours the generator would run for in the day for an overall estimate. 

  • How Much Propane Does A 14kw Generator Use Per Hour?

Ans: A 14kw generator will use approximately 3 gallons of propane per hour.  

  • How Much Propane Does A Whole-House Generator Use Per Hour?

Ans: The quantity of propane a whole-house generator will use per hour will depend on factors such as the number of hours, wattage, number & nature of appliances run, etc. 

Once you have all this data, use the equation for calculation. 

  • How Much Propane Does A 12000-Watt Generator Use?

Ans: A 12 000-watt generator will use up to 2.4-2.5 gallons of propane per hour. 

Related: Best Solar Generator For Home Backup – 6 Options for 2023


So, here you go. Inexpensive, cleaner, and accessible, Propane is the best choice to power your generator and home. However, it’s always wise to have a rough figure of how many gallons of propane you’d require to avoid any last-minute hiccups. 

To help you out, I’ve done the math above and figured out the gallons required per hour. 

You just need to multiply it by the total number of hours the generator will run, and you’re ready to go!

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