Looking to buy a generator? You’re probably considering various factors such as power rating, fuel capacity, and whether it has an ignition or kick-starts.

But what about its fuel source? You’ll come across two main types – propane and gas. How do these two compare? And which one should you get?

blue generator

With this well-researched comparison post I’ll take you through the differences between propane and gas generators.

That’ll help you pick the one that’s perfect for what you need.

Ready? Let’s dive right in!

What is a Propane Generator?

A propane generator runs on, well, propane. Propane is a form of liquified petroleum gas (LPG). And it’s one of the most common fuel sources that people use to power up their generator. It’s obtained from a process of natural gas processing and petroleum refining.

It requires a separate propane tank that’s connected to the generator with a pipe. When the tank runs out of fuel, you can disconnect it from the generator. And then just get it refilled from the nearest gas station or LPG provider.

What is a Gas Generator?

A gas generator is powered by natural gas, supplied by the direct line installed in your house or through a gas tank. It consists of methane and a few other gases.

Natural gas is another popular source for fueling generators, because it’s more readily available inside homes, offices, hospitals, etc.

These generators come in various sizes and power ratings, and you can choose depending on your energy requirements.

Which Fuel to Choose For Your Generator?

Now that you have a basic idea of what propane and gas generators are, let’s look at some factors used to compare the two types of fuel. First off, you need to determine which one is more suitable for your use.

For instance, if you know you’ll be using the generator once in a blue moon, you can go with propane generators. That’s because propane doesn’t lose its quality or effectiveness, no matter how long you keep it inside the tank.

gas tank
Generator can run on either Propane or Gas.

Here are some other factors you should consider when choosing between the two popular fuel sources.


Natural gas is more readily available as it comes from the gas line in your home. On the other hand, you have to refill your propane tank from the nearest gas station. This can be a little burdensome, especially if the nearest gas station isn’t really near.

So natural gas is the way to go if you’re concerned about availability. But if you’re using a cylinder for natural gas too, then it won’t be very feasible for you.


If you don’t intend to use the generator too often, it’ll be lying idle for the better part of the year. In that case you need a fuel source that doesn’t lose its effectiveness or quality when not in use for long periods.

If you have a natural gas generator with the supply coming from the direct line, you can simply turn it on whenever you need to power up your generator.

You can also keep a propane generator for a long time without using it since liquid propane doesn’t lose its quality over time. When comparing both fuel sources based on longevity, it’s more of a tie.


If your generator is going to be lying idle for the most part, you may have to choose your fuel source carefully.

Most generators that are powered by gasoline or diesel tend to get choked up and have difficulty in starting up. Even natural gas generators take a lot of effort to start up, especially in cold weather.

On the other hand, propane gas generators easily start in any condition, regardless of the weather or how long it has been sitting idle. This makes it one of the most suitable fuel sources for standby generators and for cold conditions.

Operating Noise

When you turn on a generator, you’re actually powering up an engine! So there’s going to be noise, whether you like it or not (mostly not).

Some generators are less noisy than others though. Propane generators are much quieter than natural gas generators.


You don’t want to become a part time technician do you? So consider the level of maintenance you’ll have to put up with.

Since generators have an engine, they certainly require periodic maintenance. However, owners of propane generators have little to worry about. That’s because propane ones don’t leave any residue or buildup inside the fuel lines or generator components.

Natural gas generators are also low maintenance. But they do require the occasional servicing.


When comparing energy between propane and natural gas, remember that the former expels twice as much energy per cubic foot than the latter.

Propane burns at 2,490 BTUs per cubic foot, whereas natural gas only lets out 1,040 BTUs per cubic foot. This means that in a span of 1 minute, less propane is consumed.

However, this doesn’t mean that propane would be cheaper than natural gas. We’ll cover that later.


Instead of focusing on the cost of propane and natural gas, I’ll talk about the cost-effectiveness of each.

As we know already, propane generators are powered by a propane tank that needs to be refilled from time to time.

If you have a larger tank you’ll have to pay up a larger amount every time you top it up. Even then, propane generators are much cheaper than gas generators.


Last but not the least, the purpose and location where you’re using the generator also comes into play when comparing propane and gas generators.

Normally, most households use natural gas generators because of the readily available natural gas supply.

house generator
Consider your location and purpose when choosing a generator

This reason also makes natural gas generators suitable for hospitals, offices, schools, and many other public places and important institutions that can’t afford to have a power outage.

On the other hand, propane generators are more used for camping trips, picnics, hunting trips. Basically any event that has to do with the outdoors.

You can easily carry a small propane generator with its tank inside your RV or caravan, and you can power it up whenever you need to.

Can You Use Natural Gas in a Propane Generator?

Simply put, a generator that’s built to run on propane gas won’t be suitable for use with natural gas. You may have seen many videos and articles that show you how to do it.

Let me warn you that it can be extremely dangerous if you try something like this without consulting your technician first!

It can happen. There’s a sudden power outage and you don’t have any propane left in your tank and you can’t go out to get it refilled. You’re tempted to look for a workaround that allows you to convert your propane generator to run on natural gas.

Technically, yes, there is a way to convert it. Conversion kits are also available that you can buy and use to make it a dual-fuel generator. But this is also not entirely safe.

Plus, there can be a lot of performance issues that arise from using different kinds of fuel sources.

Propane has twice as much energy as natural gas. So when your generator runs on gas, it will start to sputter and run at a much less horsepower. This can also damage any appliances you’re running on the generator like this.

Really think you’d need more than one fuel source for your generator in case of an emergency? I suggest you go for a dual-fuel or tri-fuel generator instead of modifying your existing propane generator.

How Long Will a Generator Run on a 20lb Tank of Propane?

The amount of time your generator will run on a 20lb tank of propane doesn’t just depend on the volume of fuel that you have. Other factors such as the horsepower of the generator and the load applied on it also come into play.

Let’s assume that we have a 10-horsepower generator that typically operates at 50% load, which means it runs at 5hp. Now, 1 horsepower produces 500 watts of energy per hour under load, so 5hp generates 2,500 watts.

Since each horsepower consumes 10,000 BTUs per hour, your generator will be burning 50,000 BTUs every hour.

Also, propane contains 92,000 BTUs per gallon. Considering that your propane generator has a 20# cylinder and a gallon capacity of 4.8, the total BTU capacity comes up to 441,600 BTUs.

Since your generator consumes 50,000 BTUs per hour, dividing the total BTU capacity by this figure gives us 8.8 hours. If the load on the generator is increased, this figure goes down. However, if the generator’s horsepower is greater and the load remains the same, the time will also increase.


Both propane and natural gas are clean-emission fuel sources that can be used to power up your generators.

Natural gas has a more steady supply and doesn’t require any upfront cost or refilling.

On the other hand, propane has more energy and is suitable for powering up generators that run once in a while.

I hope this post clarified things for you in terms of choosing between propane and gas generators. Keep the factors I talked about in mind and you’ll make the right choice.

Found this post helpful? Want to learn more about similar topics? Feel free to check out similar articles on our site.

Thank you for reading, and have an amazing day!