LTL Shipping: What Is Minimum Density/Cubic Capacity?

For someone new to the world of LTL shipping, one of the first things that anyone must learn and always be aware of is whether or not their shipment has reached or is close to reaching Cubic Capacity. LTL (less than truckload) freight differs from FTL (full truckload) in many ways but never more so than in this instance. When shipping FTL, you cannot hit cubic capacity as you have rented the entire vessel and it is yours to fill as much or little as you desire. 

With LTL shipping, you have a limit as to how much space you are allowed to occupy, as well as strict limits concerning the absolute minimum amount of weight that a shipment must hit. Think of it as the sign in front of a ride at an amusement park that states, “You Must Be Of ‘X Size And Weight’ To Ride The Roller Coaster.”

Hitting cubic capacity can cause a freight quote to become invalid and can often double or even triple the initial price quote received. Knowing how this works is crucial for making sure that a shipment does not exceed the limits of what is considered an LTL shipment.

When A Shipment Hits Cubic Capacity

1.  A few exceptions with certain carriers aside, an LTL freight shipment hits Cubic Capacity whenever the shipment’s density reaches the magic number of “750 cu. ft. > 6.” Or “the 750 & 6 rule.” (Learn how to calculate density.)
2. That magic number translated essentially means that when a shipment has exceeded 750 cubic feet and its density is less than 6 pounds per cubic foot.
3. Calculating whether or not a shipment has hit cubic capacity is fast and easy and follows the same basic guidelines of calculating a shipment’s density as you normally would whenever trying to figure out what class your freight is.

Scenario #1

1. Multiply the Length, times the Width, times the Height of your shipment (L x W x H). For example, if you have a shipment that is 6 stackable pallets and each pallet is 40″L x 48″W x 48″H then you would multiply those dimensions and reach a number of 92,160. Multiply that number by 6 since there are six of those pallets and you reach a number of 552,960. Take 552,960 and divide it by 1,728 as you would any shipment when calculating its density, and you get a number of 320 cubic feet. 320 cubic feet is less than 750 cubic feet. So far so good!
2. Now let’s take the total weight of the shipment. For example, let us say that this shipment weighs 6,000lbs or roughly 1,000lbs per pallet. Divide your weight by your cubic footage (6,000/320=18.75). 18.75 would be the density of the shipment.
3. This hypothetical shipment is now for the purposes of this discussion, 320 & 18.75. That makes it a Class 70 shipment and it is safe to ship as LTL as it is far and away from hitting the “750 & 6” rule.

Scenario #2

1. What if however, you have 7 pallets that are 42L x 48W x 96H and are non-stackable? Using the previous formula you would be at 193,536 per pallet. Multiply that by 7 to get 1,354,752. Divide that by 1728 and you get 784 cubic feet. If the pallets weigh the same as in the previous shipment (1,000lbs per pallet) then you would be at 784 & 8. Still, here you are safe because, even though you have gone over 750 cubic feet, your density is still higher than 6 pounds per cubic foot and this can still qualify as an LTL shipment.

Scenario #3

1. Now let’s say you have 7 pallets, all 42L x 48W x 96H, that are all non-stackable, but the weight of each pallet is not 1,000 lbs each but is now only 500lbs per pallet? While your cubic feet at that point remains the same at 784, your density is now only 4 pounds per cubic foot. This is an example of a shipment that has hit Minimum Density/Cubic Capacity because it has broken the “750 & 6” rule. It has exceeded 750 cubes and is lighter than 6 pounds per cubic foot.

Related Reading: Check out our other LTL Shipping 101 posts

BONUS: Just because you have an NMFC code that states your freight is a certain class based on the item itself, it is considered best practice to calculate and quote a freight shipment based on its actual density in order to prevent possible reclassification by the carrier after a pick. Reclassification charges, while not nearly the cost of a shipment hitting Cubic Capacity, can still cause a shipment to significantly increase in price.