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How Much Does a Gallon of Diesel Weigh?

As a truck driver, you need diesel fuel to get your load from Point A to Point B. You’ll fill up on a regular basis to keep the wheels turning and income rolling in every day. You’re unlikely to even consider the weight of the fuel until you roll onto a scale and your truck and load are over the legal limit. This means lost time and an unnecessary expense. 

By now you’re probably wondering how much a gallon of diesel weighs and how to calculate the diesel weight per gallon. Read on and find out. 

What Is the Weight of Diesel Fuel?

A widely accepted guideline for truck drivers is that a gallon of diesel fuel weighs around seven pounds. Though fuel tanks come in different sizes, most truck diesel tanks take between 125 and 300 gallons of fuel. 

There is a fuel tank located on either side of the trailer. The diesel is divided between the tanks to ensure even distribution of weight across the axles. Depending on the size of the tanks, a truck that has just filled up will carry between 875 and 2,100 pounds of fuel. 

Why Is It Important to Know?

Trucks must adhere to weight limitations, and weight stations play a crucial role in enforcing these regulations. Exceeding these limits can lead to damage to public infrastructure, prompting authorities to establish and enforce these restrictions.

Truck size and weight standards are set by both federal laws and state laws. Federal laws limit the gross weight of the truck and the load to a total of 80,000 pounds. The limit is 20,000 pounds on a single axle and 34,000 pounds on a tandem axle. 

These controls hold for the transport of loads on the Interstate System. Any commercial trucks weighing in at 10,000 pounds or more must stop for weight inspections. 

When you fill up, the weight of the vehicle will increase, affecting fuel consumption. In addition, if you’re carrying a load that is close to the weight limit you could fall foul of the law. 

If you’re caught hauling a vehicle that is over the weight limits, you’ll not only pay a fine, but you’ll also lose time as you offload cargo and arrange for alternative transport to get the goods to their final destination.  

Understanding the Location of Fuel Tanks

Diesel trucks have tanks on either side of the truck. The fuel pump draws from both tanks to ensure that the weight stays balanced. Semi-trucks often have two tanks on either side of the trailer. 

The diesel weight lies mostly on the steering axle or drives. Drop nose rigs typically carry their tanks under the cab doors on the frame. The tanks of long hood trucks are usually located beneath the bunk. 

What are the Different Types of Diesel?

There are two standard diesel types used in diesel trucks in the U.S.   

  • Diesel 1D: This is the least viscous of diesel fuels. It is mainly used in cold climatic conditions.
  • Diesel 2D: This is the type of diesel that is used most commonly as it is suitable for normal to warmer climates. Higher viscosity offers better lubrication for the moving parts of the engine. Sometimes, 1D is mixed with 2D for a winter diesel mix.
  • Diesel 4D: This is designed for low-to-medium speed motors where the load and speed are constant. It has the highest density of all diesel fuels and it is used in railroad trucks and generators. 
  • EN 590 Diesel: This is the type of diesel fuel most commonly sold in European countries.

What Impacts the Weight of Diesel?

Measuring the weight of diesel is not as easy as you might expect. There are several factors that affect the weight to volume ratio.


Diesel fuel weight can slightly vary with temperature changes. In colder conditions, diesel can thicken, potentially causing filter clogs at 5°F, and it becomes denser. Conversely, in warm temperatures like 110°F, a gallon of diesel weighs approximately 6.8 pounds.

Fuel Grade

The varying viscosity of the various diesel grades creates weight differences. Viscosity affects boiling point, pour point, and cetane rating. The average weight is as follows: 

  • Diesel 1D: 7.3 pounds per U.S. gallon
  • Diesel 2D: 7.09 pounds per U.S. gallon
  • Diesel 4D: 8 pounds per U.S. gallon
  • EN 590 Diesel: 6.96 pounds per U.S. gallon 

Measurements and API

The American Petroleum Institute gravity otherwise known as API gravity measures the specific gravity or weight of petrol or diesel. It is an inverse measure of the weight of petroleum products against water. 

Light oil with a specific gravity of more than ten will float on water. Fuel with a specific gravity of less than ten falls into the category of heavy fuel as it will sink below the surface of the water. The lower the API the higher the energy level.

There are three different gallon measures. How you convert your gallon to weight can cause a discrepancy. The imperial gallon is the heaviest but the U.S. gallon is the international measure. 

  • Dry Gallon: 7.93 to 9.32 pounds
  • Imperial Gallon: 8.19 to 9.61 pounds
  • U.S. Gallon: 6.82 to 8 pounds

Know the Weight of Your Diesel and Save Time and Money

If you’re a diesel truck driver, it’s important to know how to calculate the weight of the diesel in your tanks. Unless you do, you could fall foul of the law when weighing in. Calculating the weight isn’t that difficult. 

For a quick estimate, multiply the number of gallons in your tank by 7. This simple calculation provides a reasonably accurate measure of the diesel load in your tanks.

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