How Much Does a Gallon of Diesel Fuel Weigh?

Diesel Steve Snodgrass Flickr Picture Courtesy: [Steve Snodgrass/Flickr]

One U.S. gallon of automotive diesel fuel at 76 degrees Fahrenheit and standard atmospheric pressure weighs 6.91 pounds. That’s equal to 110.54 ounces or 3.13 kilograms. The density of a substance can change due to heat and pressure, so this number may change slightly in different environments. Colder temperatures and higher pressures increase the weight of a gallon. However, it doesn’t change too much under normal conditions, so many truck drivers estimate the weight of fuel at 7 pounds per gallon.

Physical Properties

Petroleum diesel, also known as petrodiesel, is the most common type of diesel. This fuel is made by distilling crude oil at high temperatures. It looks clear or brown in liquid form. It’s sometimes mixed with bio-fuels. Diesel has a high energy content, meaning it provides a lot of power when used. While diesel can be stored for long periods of time, it does

degrade over time.

Like gasoline, diesel has an octane number that refers to its energy value. It comes in different grades: number one, which is premium, and number two, which is regular. Off-road diesel is made only for construction vehicles, agricultural equipment, and other machines that will not be used on paved roads. It’s usually dyed red. Use of off-road diesel on regular roads can lead to fines.


Differences Between Gasoline and Diesel

The reason why diesel is often used in large vehicles is that it carries more energy than gasoline. Diesel molecules are large yet compact well against each other, packing more energy into every gallon. Compared to diesel’s roughly 7 pounds per gallon, the same amount of gasoline weighs only about 6.2 pounds. While

diesel releases more harmful substances into the air when burned, it’s more fuel efficient. Diesel vehicles also require special engines that don’t need spark plugs to ignite the fuel.


Diesel in Cold Weather


Because diesel is denser than gasoline,

it’s more prone to freezing. Cold temperatures cause thin, waxy sheets of semi-solid diesel to form. This can clog an engine’s fuel filter. Water content in the fuel, which is especially common in biodiesel, make it even easier for the diesel to freeze. If diesel looks cloudy or hazy, it may be freezing.

Treating Frozen Diesel


Chemicals can be added to diesel to keep it from congealing. If the diesel has already begun to turn waxy, adding number one diesel or kerosene to the engine can dissolve the wax. However, doing so is costly and lowers the efficiency of the fuel.


Heat can also turn the wax back into a liquid. Many diesel vehicles come with a means of heating the fuel tank for this purpose, but if the temperature gets too cold, it may not be enough.

The History of Diesel

The diesel engine was invented by Rudolph Diesel in the 1890s in an attempt to create more efficient vehicles. Rather than focusing only on petroleum, Diesel tried using everything from coal dust to vegetable oils as fuel. He was really invested in the latter and predicted that

plant oils would someday be as important as petroleum

While Diesel’s engines faced problems with reliability in his day, they were still more efficient than his competitors’. They were also strong enough to be used by the French navy in 1904. While the diesel engine would go on to further successes, Diesel did not live to see this happen. He vanished off a ship headed to England in 1913. Some believe that he committed suicide. Others suggest that he may have been murdered by oil magnates who were threatened by his push to use biofuels.