How Much Does a Gallon of Oil Weigh?

With the ever-increasing shipping and cargo costs globally, it is essential to know the oil weight to comply with cargo and weight regulations. This will help you understand how to cut costs. We generally talk about oil in liters, gallons, or barrels. However, that’s the volume of oil; what about its weight? So, let’s read more about how much a gallon of oil weighs.

What Is the Weight of One Gallon of Engine Oil?

There is considerable confusion in public regarding the weight of engine oil and its grade. Many people assume that the quality of engine oil has a link with its weight. However, the grade of motor oil is its viscosity, and its weight still needs to be calculated.

What Is the Weight of One Gallon of Engine Oil

If you read 5W-20 on the motor oil label, 5W is the grade of oil. However, 20 is the temperature in the degrees the oil was measured. So, on average, a gallon of 5W-20 motor oil will weigh around ten pounds per gallon.

How Much Does Olive Oil Weigh?

Olive oil’s weight usually depends upon the quality of olives. On average, olive oil can weigh 7.6 pounds per gallon.

Weight of Vegetable Oil

Vegetable oil is a little less viscous than motor oil. As such, vegetable oil weighs around eight pounds per gallon. Due to less viscosity, any factors do not affect vegetable oil.

Weight of Corn Oil

Corn oil is almost identical to vegetable oil in viscosity and weight. Thus, both weigh eight pounds per gallon.

Weight of One Gallon of Crude Oil

Crude oil weighs from 6.5 pounds per gallon to 8.5 pounds per gallon, depending on crude oil quality. Because temperature variations highly impact oil weight, the petroleum sector utilizes measures that allow for such fluctuations.

Grades of Crude Oil

Many countries have different terms for the grades of crude oil. However, Americans use light, medium, and heavy to demonstrate natural oil quality. Depending upon the conditions, the weight of a gallon of light, medium, or heavy crude changes by one quarter to half a pound per gallon from the previous order.

Grades of Crude Oil

Light Crude Oil

Refineries create more petroleum products like turbine fuel, motor fuel, jet fuel, and aviation gasoline. Therefore, light crude oil sells for a hefty price. Light crude oil has an extremely low density and viscosity at room temperature, allowing it to flow easily. The carbon chain in light crude oil is thinner than in heavy oils.

Medium Crude Oil

The US Energy Information Center’s higher criteria describe medium crude oil containing an API gravity of 40 to 30. Medium oil generally has longer carbon chains and yields fewer oils than light crude oil.

Heavy Crude Oil

A low API gravity and a high specific gravity characterize heavy crude oil, which is why it requires more refining. Heavy crude oil has longer hydrocarbon chains than other natural oils, and it contains more impurities like sulfur.

Heavy crude oils take more refining and produce fewer amounts of petrol, methanol, and other products. So, they attract lower prices in the worldwide industry.

Is Stored Crude Oil Renewable?

No, stored crude oil is not renewable. The hydrocarbon chains in the stored natural oil break with time. This breakage of chains results in the spoilage of crude oil.

How to Calculate the Weight of a Gallon of Oil

If you know the volume of oil, you need its density and temperature to calculate its weight. The methods used for this purpose are specific gravity and API gravity.

Specific Gravity

The density of a liquid is measured with a reference liquid, such as water, at a certain temperature. The specific gravity is first calculated by dividing its mass by its volume. Next, you should divide the answer by the density of water at the same temperature.

You can determine a liquid’s current weight by multiplying its specific gravity by the density of water in pounds per US gallon (pounds per gallon) at a particular temperature.

API Gravity

Because the API gravity of oil is inversely proportional to its density and lower density oils yield price increases, API gravity is essential as a measure of value—divide 141.5 by the oil’s specific gravity to calculate API gravity, minus 131.5.

Factors Affecting Weight of Oil


Viscosity is the main factor affecting how much a gallon of oil weighs, and density means the resistance of a liquid to flow. Like, honey is denser than water because honey is more resistant to flowing if they flow on the same surface.

In a viscous liquid, molecules are tightly packed with each other. This allows the liquid to fit in more molecules in a tiny space, increasing weight.


Temperature also plays a vital role in how much a gallon of oil weighs. When oil is at a low temperature, its molecules are cool and settled down. As the temperature increases, its molecules become active and excited, thus moving at high speeds. This is the reason why heating oil weighs more than cold oil. The motion of molecules is so fast that it thins down the oil, thus decreasing the weight. This is why all the oil weights are registered with the temperature at which they were measured.


Low pressure does not affect the oil weight. However, high pressures can compress the liquids and force their molecules together, resulting in a weight decrease.


There you go – a detailed answer to how much a gallon of oil weighs. You should keep in mind many factors while asking how much a gallon of oil weighs; for instance, motor oil depends mainly on its grade. Similarly, if you want to know how much crude oil weigh or how much vegetable oil weigh, you should check the number of factors it relies on.

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