How Much Does a Gallon of Gas Weigh?

To save on gas money, I’m brainstorming some creative ideas. One thought is to keep my car’s gas tank half-empty while driving. The theory behind this is that a lighter car tends to have better gas mileage.

So, let’s say I can drive with seven gallons less gas in my tank on average. I’m curious to know how much weight that would remove from my car. How much does gasoline weigh per gallon?

How Much Does a Gallon of Gas Weigh?

The weight of a gallon of gasoline is about six pounds. That’s just an estimate because it can vary depending on the type of gasoline and what’s mixed into it. So, if you empty seven gallons from your tank, you’d be shedding roughly 42 pounds of weight from your car.

Now, here’s the reality check. If your vehicle weighs over 3,000 pounds, dropping 50 pounds won’t magically make your fuel expenses disappear. Sorry to burst your bubble! You see, gasoline is about 25% lighter than water, which weighs around 8.4 pounds per gallon. That’s because there are some gases dissolved in it.

Although driving around with a half-empty tank won’t turn you into a fuel efficiency champ, it’s still good to know the weight of the gas. Imagine if your car breaks down and you have to haul some fuel.

Carrying a single gallon from the nearest gas station won’t be too much trouble, but lugging around a five-gallon container? That’s a hefty 30 pounds! You might find yourself struggling on the way back to your car. So, be prepared for that little adventure!

What Factors Influence the Weight of Gasoline?

According to the Science and Technology Desk Reference, they say that a gallon of gasoline in the U.S. weighs around 6.1 pounds. But here’s the thing, the weight of gasoline can be affected by the quality of the fuel.

In the U.S., gas stations offer three main grades of gasoline based on their octane level. You’ve got Regular, which is the lowest grade with an octane rating of around 87. Then there’s Midgrade, which falls in the middle range with an octane rating of about 89 to 90. And finally, you’ve got Premium, the highest-grade gasoline with an octane rating of usually 91 to 94.

When it comes to weight, Regular gasoline is the lightest, weighing approximately 6.073 pounds per gallon at a temperature of 59 degrees Fahrenheit. On the other hand, Midgrade gas weighs about 6.35 pounds per gallon, and Premium gas weighs around 6.27 pounds per gallon under the same conditions.

Now, keep in mind that temperature plays a significant role in the weight of gasoline. For example, a gallon of Premium 93-octane fuel can vary in weight between 5.93 and 6.42 pounds, depending on factors like temperature and additives such as methanol, water, and benzene.

It’s also worth noting that volume is affected by temperature, but the calculations are straightforward. A temperature increase of 1 degree Fahrenheit adds about one part per million (ppm) to the volume.

So, a temperature difference of 30 degrees Fahrenheit can expand the volume by roughly 3%. This means that if you’re refueling during the winter, you’ll be pouring more gas into your vehicle due to the colder temperatures.

So, there you have it! Gasoline weight can vary based on factors like fuel quality, temperature, and even volume. It’s always good to keep these things in mind, especially when you’re at the pump.

How Much Does My Full Fuel Tank Weigh?

Some people think that driving around with a half-empty or almost-empty tank would save them money because the car would be lighter. Sounds good in theory, but it doesn’t actually help you save on fuel costs in reality.

Let’s break it down. Smaller tanks can hold around 12 gallons, while larger ones can go up to 15-20 gallons. SUVs and big trucks can even hold a whopping 27 gallons.

So, if we average out the tank capacity and fuel weight, we’re looking at a full tank weighing anywhere from 73 to 165 pounds, like the weight of a teenager. But here’s the thing—it doesn’t make a big difference when compared to the average vehicle weight of 2000 to 5000 pounds.

On top of that, driving with a nearly empty tank can cause all sorts of car troubles. So, it’s better to avoid it altogether.

Diesel Vs. Gasoline

Diesel is actually heavier than gasoline, weighing around seven pounds per gallon (a bit less in the US and a bit more in Canada). The reason for this is its higher density and the number of molecules it contains. It’s important to know this because you should never mix regular gasoline and diesel together.

If your vehicle runs on gasoline and you accidentally fill the tank with diesel, the diesel will sink to the bottom of the engine tube due to its weight. On the other hand, if you have a diesel-based car and you put regular fuel in the tank, it will float to the top and remain there until all the diesel is burned.

Mixing these fluids can lead to serious issues with your vehicle, and you may even need a procedure called “gastric lavage” to fix the problem. While you might get lucky and avoid major consequences the first time it happens, it’s best not to take any chances and be cautious.


In emergencies when you run out of fuel, it’s crucial to consider the weight of gasoline. Factors like octane level, temperature, and additives also play a role, which is good to keep in mind. But hey, most people don’t bother with exact measurements.

So, if you want to be practical, just remember that gasoline weighs around 6 pounds per gallon, which is about 25% lighter than water.