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 limits. 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. Keep reading to find out. 

Key takeaways

• A standard rule of thumb in trucking is that diesel weighs about seven pounds per gallon, though the exact weight varies by type and conditions.
• Temperature significantly affects diesel weight; warmer diesel is lighter. while cooler diesel is denser and heavier.
• There are several types of diesel fuel with different weights. with #1 diesel (6.9 lbs/gal), #2 diesel (7.1 lbs/gal), and biodiesel (7.2 lbs/gal) being the most common.
• Knowing diesel weight is crucial for truckers because exceeding federal weight limits (80,000 pounds total) can result in fines and delays at weigh stations.
• A full truck’s fuel tanks can add between 875 and 2,100 pounds, depending on tank size.

What is the weight of diesel fuel?

A widely accepted trucker guideline is that a gallon of diesel fuel weighs around seven pounds. For example, if you wanted an approximate idea of how much 100 gallons of diesel weighs, you’d multiply 100 by seven to get an estimate of 700 pounds. For 300 pounds of diesel, the estimated weight would be 2,100 pounds, and so on.

Though fuel tanks come in different sizes, most truck diesel tanks take between 125 and 300 gallons of fuel. Depending on the size of the tanks, a truck with a full tank will carry between 875 and 2,100 pounds of fuel. 

Standard fuel weight measurement units

The American Petroleum Institute gravity, otherwise known as API gravity, measures the specific gravity or weight of gas 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

Why is it important to know how much diesel fuel weighs?

Trucks must adhere to weight limitations, and weigh 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 weight of 80,000 pounds. The limit is 20,000 pounds on a single axle and 34,000 pounds on tandem axles. 

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

When you fill up, the total 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.  

What are the different types of diesel?

Diesel fuel comes in several types, each tailored for specific engines, climates, or applications. Here are the most common types, including their approximate weights at 60° Fahrenheit (F).

#1 diesel (d1)

• Characteristics: Lighter, less viscous, and lower energy content than #2 diesel
• Uses: Used in colder climates due to better cold-weather performance; it resists gelling in low temperatures
• Advantages: Improved flow and combustion in cold weather conditions
• Disadvantages: Lower fuel efficiency and less lubricity compared to #2 diesel
• Weight: About 6.9 pounds per gallon (lighter due to lower density)

#2 diesel (d2)

• Characteristics: Heavier, denser, and contains more energy than #1 diesel
• Uses: Standard diesel for most trucking vehicles and machinery; suitable for warmer climates and heavy-duty engines
• Advantages: Higher fuel efficiency and better lubricity, which helps reduce engine wear
• Disadvantages: Gels at low temperatures unless additives or blending with #1 diesel are used
• Weight: About 7.1 pounds per gallon (heavier due to higher density)

Winterized diesel

• Characteristics: A blend of #1 and #2 diesel, or #2 diesel treated with anti-gel additives
• Uses: Designed for use in cold climates to prevent gelling and improve cold flow properties
• Advantages: Performs well in winter without compromising efficiency too much
• Weight: Between 6.9 and 7.1 pounds per gallon, depending on the blend ratio of #1 and #2 diesel

Biodiesel

• Characteristics: Produced from renewable sources like vegetable oils, animal fats, or algae. Common blends are b5 (5% biodiesel, 95% petroleum diesel) and b20 (20% biodiesel, 80% petroleum diesel).
• Uses: Compatible with most diesel engines without major modifications
• Advantages: Lower emissions, renewable, and biodegradable
• Disadvantages: Higher gel point than petroleum diesel, potential compatibility issues with some engines or materials
• Weight: About 7.2 pounds per gallon on average (varies based on blend and source material)

Renewable diesel

• Characteristics: Made from renewable sources but chemically identical to petroleum diesel
• Uses: Direct replacement for petroleum diesel in any diesel engine
• Advantages: Lower emissions, excellent performance, and compatibility
• Disadvantages: Limited availability and potentially higher cost
• Weight: Approximately 6.8–7.0 pounds per gallon, depending on its chemical composition

Ultra-low sulfur diesel (ULSD)

• Characteristics: Contains significantly less sulfur (<15 parts per million) compared to older diesel fuels
• Uses: Required fuel grade for modern diesel engines with advanced emission controls
• Advantages: Reduces sulfur emissions, meeting environmental standards
• Disadvantages: Slightly less lubricating than older diesel, requiring additives
• Weight: Around 7.0 pounds per gallon (slightly lighter than traditional diesel due to lower sulfur content)

Dyed diesel (off-road diesel or reefer fuel)

• Characteristics: Contains a red dye to indicate it is untaxed fuel for off-road use
• Uses: Agricultural, construction, or industrial equipment not used on public roads
• Advantages: Cheaper due to tax exemption
• Disadvantages: Illegal for use in on-road vehicles; heavy penalties if misused
• Weight: Same as #1 or #2 diesel, depending on the specific type used (6.9–7.1 pounds per gallon)

High-performance diesel

• Characteristics: Premium diesel with higher cetane levels and additional additives
• Uses: For high-performance engines and vehicles requiring enhanced efficiency and reduced emissions
• Advantages: Cleaner engine operation, better performance, and reduced emissions
• Disadvantages: More expensive than standard diesel
• Weight: Roughly 7.0–7.1 pounds per gallon, similar to #2 diesel

Each diesel type is optimized for specific conditions or applications, so choosing the correct type is critical for performance, longevity, and compliance with regulations.

What impacts the weight of diesel fuel per gallon?

Several factors impact the weight of diesel fuel per U.S. gallon, primarily through changes in its density. Here are the main factors:

• Temperature: Diesel fuel expands when heated and contracts when cooled. Warmer diesel has a lower density, making it weigh less per gallon, while cooler diesel is denser and heavier.
• Type of diesel: Different types of diesel have varying chemical compositions and densities. For example, #1 diesel is lighter than #2 diesel because it has fewer heavy hydrocarbons.
• Additives and blends: Additives (such as anti-gel agents, stabilizers, or detergents) and blends (such as winterized diesel or biodiesel) can alter the density and therefore the weight. For instance, biodiesel tends to be denser than petroleum diesel, increasing the weight.
• Sulfur content: The sulfur content in diesel can slightly affect its weight. ULSD has a lower density compared to older high-sulfur diesel.
• Moisture content: Water contamination in diesel fuel can increase its weight. Even small amounts of moisture can affect measurements, especially in large quantities.
• Fuel quality and refining process: The refining process and the crude oil source influence the chemical makeup of diesel. Variations in refining methods can lead to differences in the density of the distillate.
• Impurities: Impurities or contaminants, such as dirt or other fuels mixed in, can affect the weight and density of diesel.

Because of these factors, diesel is typically measured by volume (gallons or liters) and weight calculations are standardized to a reference temperature (usually 60°F).

Know your diesel fuel weight per gallon

So, how much does a gallon of diesel fuel weigh? Although the answer varies, multiplying the number of gallons in your tank by seven will always give you a decent rough estimate.

Keeping an eye on this weight is important for several practical and safety reasons, particularly in industries like trucking, transportation, and construction. Ultimately this simple calculation can save you hundreds or thousands of dollars in fines, prevent delays, and even save lives.

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