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Freight Density: How it Shapes Your Shipping Strategy

Resources > Freight Density: How it Shapes Your Shipping Strategy
Discover the pivotal role freight density plays in estimating your shipping costs. Freight density, as outlined by industry authority NMFTA, directly influences the freight class of your shipment and is integral to determining costs.
Published: February 6, 2020
Last Modified: August 28, 2023
Author: Natalie Kienzle

Over the past few years, the growth surge in the world of eCommerce and related markets has resulted in the use of freight density for cost calculation. Every item, from a feather-light foam to a heavy metal machinery part, presents its own unique challenge. Not knowing how it affects your costs could make or break your shipping strategy. 

Freight density is how much space an item takes up in a truck in relation to its weight. It’s calculated by taking the weight of the item in pounds, divided by the item’s volume, and measuring in pounds per cubic foot. This measurement plays a crucial role in determining shipping costs, packing requirements, and even the mode of transportation.

We are going to take a comprehensive look at freight density and everything that’s involved in it for you to plan your shipping strategy. 

freight density used to measure boxes packages on a rolling conveyor system.

What is Freight Density?

To put things simply, freight density refers to the amount of space that an item may occupy in relation to its shipping weight. There are different complications when it comes to finding an accurate freight density, and they’ll be explored as the article goes on. 

This measurement is then used to determine how much it would cost to ship your products. Knowing your freight's density early on can help prevent costly adjustments. If the freight density is incorrectly reported, you may face additional charges when the freight is reweighed and measured at the terminal.

We’re going to look into a few ways that this ends up impacting shipping and logistics:

  • The influence of freight density on shipping costs
  • How freight density affects cargo loading and unloading
  • The role of freight density in determining freight class
  • The importance of accurate freight density calculation in logistics planning.

By the end, you’ll have a strong working knowledge of freight density and how it impacts different shipping options. 

The Role of Freight Density In Shipping and Logistics

One of the most crucial aspects of freight density is its influence on shipping costs. There's a strong connection between the two, with density directly impacting your freight rates. Another critical role of freight density lies in the calculation of freight class, a standardized classification system used in the freight industry.

We’ll take a look at freight class later on, but for now, it’s important to note two main things:

  • Shipments that take up more room per weight will ultimately cost more to ship. 
  • A shipment that is heavier yet more compact, will often cost much less to ship

While it may seem simple enough, freight density in shipping does get far more complicated. Let’s consider other ways in which density and cost are connected.  

What is the Connection Between Freight Density and Freight Costs?

Shipping high and low density items is less about weight and more about the efficient use of space. A small, compact item, even one of considerable weight, is often easier to stack and handle. 

Their efficient use of space in a truckload or a shipping container, means more goods can be transported at once. This efficiency can result in lower shipping costs per item. On the flip side, lower density goods take up more space relative to their weight, which often leads to higher freight costs. These items may be more fragile or just an awkward shape that doesn’t disperse weight well. 

The less efficient an order is, the more it’s going to cost a shipper. For those who feel that weight should still be the biggest factor, let’s consider the following scenario. 

Imagine you're a carrier, and you have a truck that can accommodate 1,000 cubic feet of cargo. You have two customers, each wishing to ship cargo with the same volume but different densities. 

  • Customer A has a high-density cargo that weighs 10,000 lbs
  • Customer B has a low-density cargo that weighs only 1,000 lbs. 

In terms of volume, they both occupy the same space. But the low-density cargo from Customer B is significantly lighter than the high-density cargo from Customer A.

On the one hand, they can charge more to Customer A because they're using more of the truck's weight capacity, a critical resource in truckload shipping since it affects fuel consumption.

The low-density cargo isn’t adding much weight, but does take up valuable space. By not being able to use that space for another client, the carrier makes less profit overall. This translates into higher shipping costs for Customer B. 

Charging by density means that weight and volume don’t tip the scale too hard in one direction or another and lead to steadier pricing. 

However, calculating costs based purely on freight density isn't without challenges. Other factors come into play:

  • Distance
  • Fuel costs
  • Demand

Furthermore, the calculation itself can be tricky, especially for irregularly shaped items or those packed in non-standard containers. Learning how to run this calculation yourself, or at least knowing which measurements are being used, can help you plan for costs. 

Another complexity arises with freight classes. These are categories defined by the National Motor Freight Traffic Association (NMFTA) that consider density, among other factors, when standardizing freight pricing across the industry. Freight density plays a significant role in determining these classes, and thus, understanding it is crucial for accurate shipping cost predictions.

Workers loading=

How To Calculate Freight Density

While there are many online calculators that enable you to calculate freight density simply, it is always worth knowing the method, so you can quickly work out things for yourself should you need to. 

In this section, we will be breaking down the density calculation method of working out freight density.

Step 1: Measurements 

The first step to calculating density is to measure weight and volume. 

  • Weight: The total weight of the shipment, measured in pounds (lbs). It must include the commodity and any packing or packaging materials.
  • Volume: the total space that the shipment occupies, measured in cubic feet. Calculate by multiplying the length, width, and height. Divide the result by 1,728 (since there are 1728 cubic inches in a cubic foot).
    • Volume = (Length x Width x Height) / 1728

Look at a shipment as a single piece to measure all the volume dimensions in inches.  If your shipment is in multiple boxes or pallets, each one can be measured individually, or you can figure out how the combined measurements would read. 

As with weight, you should include any packaging and skids that will travel. For packages that are awkwardly sized, base the measurement on the furthest points along each axis. That is to say, height, length, and depth again. Basically, you’re placing the item in a figurative box, and then measuring that.

It might not be as accurate or straight forward as an actual box, but it does the job. When shipping items that have been brought from overseas, be sure to change measurements from metric to standard. 

Step 2: Density Formula

Once you have taken the measurements to find weight and volume, it’s time to calculate the density. For freight shipping, specifically, density is calculated by dividing the weight of the shipment by the total volume and is measured in pounds per cubic foot (PCF). T

The formula for density is:

  • Density (PCF) = Weight (lbs) / Volume (cubic feet)

It is critical that you keep the same measurement standards throughout the process. All measurements MUST follow the U.S. standardized system. If you forget to convert something from kilos or centimeters into pounds and inches, your results will not be accurate. 

Step 3: Apply Shipment Dimensions 

To illustrate this step, let’s look at a high-density and low-density example. The first is a shipment of lead bars, a heavy but compact square package. 

Lead Bars Shipment

Weight500 lbs
Length2 ft
Width2 ft
Height2 ft
Volume2 ft x 2 ft x 2 ft = 8 cubic feet
Freight Density500 lbs / 8 cubic feet = 62.5 PCF

At 500 pounds, this will count as a freight shipment, even though it’s a relatively small package. It’s not something that a parcel service is likely to work with. 

Contrast these measurements with that of a low-density item, such as cotton balls. 

Cotton Balls Shipment

Weight10 lbs
Length2 ft
Width2 ft
Height2 ft
Volume2 ft x 2 ft x 2 ft = 8 cubic feet
Freight Density10 lbs / 8 cubic feet = 1.25 PCF

This is the exact same size as the lead bars, but the final density measurement is much lower. At only 10 pounds, it might even be something easily shipped using a parcel service. However, if you need to send multiple shipments of cotton balls, perhaps as a resupply to a large store, freight shipping is still a great option. 

Remember, for multiple pieces to a single shipment; you should add them together before dividing the cubic feet of the shipment. You should also round fractions to the nearest full 

number when it comes to cubic feet.

Step 4: Use Density to Find Freight Class 

The final step of calculating freight density is actually applying it to your shipping costs. Shipments that are charged according to their density are given a specific freight class by the National Motor Freight Traffic Association (NMFTA). 

This classification system makes it possible for carriers to set pricing that accurately reflects the cost of transporting a shipment. Since its use is widely accepted, it also eliminates confusion among clients. Everyone is on the same page regarding the nature and cost of a shipment, so prices remain competitive and predictable.  

Understanding Freight Class Density

When it comes to freight class, we’ve already mentioned that it’s a standardized system of classification that is used for commodities. More specifically, it’s used for goods that are transported via an LTL carrier  (less-than-truckload).

This freight class system goes a long way to make sure that all customers only receive an unbiased price when they opt to ship via freight.

Freight class assignment is applied to a shipment based on the total density of the freight being shipped, or the specific commodity that is in transit. To keep track, there is a freight class density chart. 

What is the Freight Class Density Chart? 

The Freight Class Density Chart is a tool used to determine the freight class of a shipment based on its density. This chart is part of the National Motor Freight Classification (NMFC) guide established by the NMFTA. 

The chart lists different ranges of freight density, each associated with a specific freight class. By calculating the density of their freight, shippers can use it to identify the matching freight class. 

This is useful for many reasons:

  • Cost estimations
  • Carrier communications
  • Load planning
  • Load dispute resolutions

In short, if you’re involved in shipping, whether through LTL services or even full truckload services, access to such charts is a must. 

Loaded pallets pushed to the far rear of a dry van trailer.

How Many Freight Classes are There?

As we have already discovered, the freight class of the item you are shipping is a huge factor in being able to determine how much your freight shipment will cost. 

There are 18 different classes in total, and they range from 50, which is the cheapest and most dense, to 500, which is the most expensive and least dense.

When it comes to finding out what commodities go in which class, it can get rather complicated. If we try to generalize, then we can say that if an item is heavy, compact, and not really fragile, then it will fall into a lower class. 

If an item is lower in density, takes up more room, and may be susceptible to damage, then this consignment will be given a higher freight class and costs more to ship. 

Basic Breakdown of Freight Classes Based on Density

Freight ClassDensity (in pounds per cubic foot)
50Over 50
5535 - 50
6030 - 35
6522.5 - 30
7015 - 22.5
77.513.5 - 15
8512 - 13.5
92.510.5 - 12
1009 - 10.5
1108 - 9
1257 - 8
1506 - 7
1755 - 6
2004 - 5
2503 - 4
3002 - 3
4001 - 2
500Less than 1
Source: NMFTA 

This is a simplified list and is frequently updated. Even if you are able to accurately measure your shipment’s density, realize there are other factors involved. Your shipment’s density might be between 12 and 13.5, which would place it in class 85. 

However, when other factors are considered, that class could go up or down. Working with a trusted carrier is the best way to ensure your shipments are classed correctly. Reputable carriers will always use the NMFC’s updated requirements for classifying your shipments. 

Learn more in our conclusive guide to LTL Freight Classes and the NMFC. 

How does Freight Class Impact Shipping Costs?

Freight class will aid in the determination of shipping costs for carriers and clients. The assigning of freight classes properly is imperative, especially when carriers and shippers are handling combinations of heavier goods and fragile materials. 

Once goods are officially classed, the real pricing comes about. 

  • Higher freight class = higher cost
  • Lower freight class = lower cost

When there is space that could be used for heavier items – those that, pound for pound, contribute more to the overall weight (and revenue) of the truckload – shippers get a better rate. 

Therefore, carriers charge more to ship lower density, higher freight class items that don’t use space efficiently. At the end of the day, the freight density calculations even things out somewhat. Even so, heavier, compact items are going to get the better deal in a freight situation. 

This is also why it’s important to get the freight class right. If the incorrect freight class is used, this can cause a backlog of issues that will ultimately delay any shipment you send. So, it may be beneficial for you to put in a little extra time and training for your employees and brush up as much as possible on freight classification.  

Warehouse working pulling a loaded pallet jack.

Factors Affecting Freight Classification and Shipping Cost

While we have examined freight density in detail, we’ve also mentioned that it’s not the only factor that determines freight class or costs. 

There are hundreds of determining factors when it comes to arranging LTL and FTL shipments, such as:

  • Travel Distance: In a lot of cases, when it comes to shipping, you will find that the greater the distance your goods have to travel, the more it will cost. Need more information about freight shipping routes? Get your cargo on the road with our handy map.
  • Travel Speed: If you are looking for a shipment to be delivered quickly, you will always find that this comes at a cost. Expedited services, regardless of density, come at a premium. 
  • FAK : Freight All Kinds, is a simple method of pricing that groups together different freight classes and allows shippers to combine them into one class. FAK is most commonly used as a tool for shippers who ship mixed pallets.
  • Special Delivery Requirements: When goods have special requirements and need additional aid from the carrier, prices go up. The fragility of a shipment can also raise its freight class and costs because the risk of damage is greater. 

While all of these things should be taken into account, the two most important things you can do when it comes to your shipment is to know the density and the NMFC freight class code it will fall into. 

Knowing both of these things will enable you to plan your shipments better and also avoid any extra costs that you may not have been expecting.   

Why Request a Freight Density-Based Quote for Your Shipping Needs? 

More carriers, LTL and others, are using density-based pricing systems within the freight industry. Much of this is due to how it promotes efficiency during the packaging process. 

Before the introduction of classifications and freight density, many businesses would simply package their shipment in the most convenient box for them, regardless of the size, quantity, or weight of the items within. Carriers and manufacturing businesses alike have come to see how wasteful this can be. 

By requesting density-based quotes, everyone in the industry benefits from the greater efficiency involved.  

  • Shippers and companies have started to use smaller packaging and attempt to confine more items to a single box.
  • More room is being saved on loaded trailers, allowing for increased deliveries due to a better use of space
  • The number of trucks needed to complete deliveries has gone down, which makes for a cleaner and greener industry

Density-based pricing has already become incredibly popular throughout the industry and has been adopted by companies using air, land, and sea. 

If you know that your shipments may end up traveling internationally, requesting quotes based on density will save you time and money down the line. 

Although NMFC numbers assigned to Freight class rankings are unique to North America, the methods for finding density are nearly universal. 

What is an NMFC Number for Shipping?

NMFC numbers (or codes) were created when transportation regulators came to realize that there was a dire need for a more effective form of standardization. In a shared effort to create a fair measure for freight pricing, the NMFTA created a classification system for every type of freight.

This system relies on the existing Freight Class system, but goes above and beyond by assigning a specific code to all types of products. 

How is NMFC Determined?

An NMFC designation is mostly based on density, but there are three other standards involved, too. The codes will also help the carrier set the shipping rates that are to be delivered to the customer.

A product’s finalized NMFC code is based on:

  • Density:  Measured as PCF using the standard density to weight formula. This becomes the base classification that is then altered by the other factors.
  • Stowability: This rates products based on how easy they are to ship and package within a trailer. 
  • Ease Of Handling: Packages that are hazardous or overly awkward for carrier employees to manage get pushed into a higher freight class that’s reflected in the code.
  • Liability:  Freight that is perishable or extremely fragile represents a greater financial risk to carriers. This often includes items that need a temperature controlled environment. 

The extent to which each of these affects the final cost is difficult to estimate. As products evolve, their codes get ranked higher or lower on the freight class chart as well. 

For the most consistent service and pricing options, keep up a good relationship with your preferred carrier. They may not be able to lock in prices all the time. However, open lines of communication go a long way towards making sure that you aren’t blindsided by changes, either. 

Harness the Power of Freight Density With USA Truckload Shipping

Whatever your shipment may be and whatever size, classification, or density, you should always be mindful of the shipping company you use. 

USA Truckload Shipping provides a trusted service that can cater to every shipping need. 

  • Full Truckload
  • Hazmat Shipping
  • Drayage Services

We have the skills and expertise to move your loads at competitive prices. Get your shipping back on track with our experienced carrier partners.  

Call us at (866) 353-7178 or get a freight quote online today. 

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