What Is Freight Class 400 in LTL Shipping?
Freight Class 400 is the lowest-density class on the current 13-tier density scale. In density-rated freight, packaged shipments below 1 lb/ft³ map to Class 400.
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What shipping class 400 means
Class 400 generally represents packaged freight that is extremely light for the amount of trailer space it occupies.
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Exact upper boundary
Anything below 1.00 lb/ft³ is in the Class 400 density band. At 1.00 lb/ft³, the density tier moves to Class 300.
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Weight alone does not determine Class 400
The same weight can produce very different densities at different packaged sizes. Class 400 depends on total packaged weight divided by final packaged cubic volume.
Freight Class 400 Density Rule & Threshold
The Class 400 density rule is simple on the current 13-tier scale: density must be less than 1.00 lb/ft³.
Class 400
Under 1
lb/ft³
Class 300
1 to <2
lb/ft³
0.50 lb/ft³ → Class 400
0.99 lb/ft³ → Class 400
1.00 lb/ft³ → Class 300
1.50 lb/ft³ → Class 300
How to Calculate Freight Class 400
Calculate cubic feet from the shipment's final outside dimensions, then divide total packaged weight by that volume. A result below 1 lb/ft³ estimates as Class 400.
Worked Class 400 calculation
Dimensions
48 × 40 × 48 = 92,160 in³
Cubic Feet
92,160 ÷ 1,728 = 53.33 ft³
Density
40 ÷ 53.33 = 0.75 lb/ft³
Estimated Class
400
Freight Class 400 Examples
Shipment examplesThese examples show how packaged dimensions and weight can produce a Class 400 density estimate. Commodity names alone do not determine freight class.
Click for full size
Empty Cartons and Packaging
A large, very lightweight pallet using the same dimensions as the primary Class 400 example.
48 × 40 × 48 in · 40 lb
0.75 lb/ft³
Estimated Class 400
Foam or Insulation Materials
A taller lightweight handling unit can remain below 1 lb/ft³ when its packaged weight stays low relative to volume.
48 × 40 × 60 in · 50 lb
0.75 lb/ft³
Estimated Class 400
Class 400 Near-Boundary Example
At 53.33 ft³, a 53 lb shipment is still below the 1.00 lb/ft³ Class 300 threshold.
48 × 40 × 48 in · 53 lb
0.99 lb/ft³
Estimated Class 400
Freight Class 400 Calculator
The calculator is preloaded with the 48 × 40 × 48 in, 40 lb Class 400 example above. Change any dimension or the weight to see how density and estimated class change.
When does this example move out of Class 400?
Class 400 weight window
For these exact 48 × 40 × 48 in dimensions, 53.33 lb remains just below 1.00 lb/ft³ and estimates as Class 400.
Into Class 300
With hundredth-pound inputs, 53.34 lb is the first value that reaches or exceeds the 1.00 lb/ft³ boundary and moves into Class 300.
Freight Class 400 vs Class 300
Class 400 and Class 300 meet at the 1.00 lb/ft³ boundary. Class 400 is below 1 lb/ft³; Class 300 runs from 1 to under 2 lb/ft³.
Class 400
Under 1 lb/ft³
Example: 48 × 40 × 48 in, 40 lb, 53.33 ft³ → 0.75 lb/ft³.
Class 300
1 to under 2 lb/ft³
Same dimensions at 80 lb → 1.50 lb/ft³.
Click for full size
The dividing point is 1.00 lb/ft³.
Below 1.00 lb/ft³ maps to Class 400. At 1.00 lb/ft³, the density tier moves to Class 300.
Freight Class 400 Requirements
There is no single commodity checklist that automatically makes a shipment Class 400. For density-rated freight, the key requirement is a final packaged density below 1 lb/ft³, while the commodity's applicable classification provisions still matter.
- Measure final outside dimensions. Include the pallet, packaging, protrusions, and overhang.
- Use total packaged weight. Include the product, pallet, cartons, wrap, and other packaging.
- Verify density is below 1 lb/ft³. Exactly 1.00 lb/ft³ is no longer in the Class 400 density band.
- Check the commodity classification. Density is not the only factor that can determine the final freight class.
Freight Class 400 Packaging Requirements
Packaging affects the dimensions and weight used in the density calculation, so measure the shipment only after it is fully prepared for transport.
- Measure to the shipment's farthest outside points, including stretch wrap, corner protection, pallet edges, and any overhang.
- Include all packaging weight in the gross shipment weight.
- Do not assume a lightweight commodity is Class 400 before checking its final packaged density and applicable classification.
Why packaging can change the estimate
At 48 × 40 × 48 in, 40 lb produces 0.75 lb/ft³ and estimates as Class 400. If the same packaged size reaches 53.34 lb, it crosses the 1.00 lb/ft³ boundary and moves into Class 300.
Freight Class 400 by Weight: Is There a Weight Limit?
Freight Class 400 does not have one universal shipment weight or maximum weight. The weight that stays below 1 lb/ft³ depends on the shipment's cubic volume.
Weight window for the 53.33 ft³ example
For a 48 × 40 × 48 in shipment, the exact volume is 53.333... ft³. At that volume, weights through 53.33 lb remain below 1.00 lb/ft³. With hundredth-pound inputs, 53.34 lb crosses into Class 300.
Class 400
≤53.33 lb
Below 1 lb/ft³
Class 300 begins
≈53.34 lb
At the 1.00 lb/ft³ boundary
How Class 400 Shipments Get Reclassified
A shipment that initially estimates as Class 400 can move to another class when the final measurements, weight, or applicable classification provisions differ from the information used for the estimate.
- The measured density reaches 1.00 lb/ft³ or more. At 1.00 lb/ft³, the shipment leaves the Class 400 density band and enters Class 300; higher densities can move into other density tiers.
- The packaged dimensions or weight were entered incorrectly. Even small changes can matter when a shipment is close to 1.00 lb/ft³.
- The commodity's NMFC provisions assign or affect classification differently. A density estimate is not a substitute for the applicable commodity classification.
Class 400 boundary example
A 48 × 40 × 48 in shipment has an exact volume of 53.333... ft³. At 53.33 lb it remains just below 1.00 lb/ft³. With hundredth-pound inputs, 53.34 lb crosses the boundary and estimates as Class 300.
What Is the NMFC Code for Freight Class 400?
Class 400 is a freight class, not a single NMFC item number. There is no universal “Class 400 NMFC code” that applies to every commodity.
Freight class
A class number such as 400 used in freight classification and rating.
NMFC item
A commodity-specific classification provision that may include density, packaging, or other requirements.
Use the commodity's applicable NMFC provisions when the final classification matters for shipping or billing.
Does FedEx Freight Use Class 400?
FedEx Freight’s current 13-tier density guidance places density-rated freight below 1 lb/ft³ in Class 400. At 1.00 lb/ft³, the density tier moves to Class 300.
Continue Planning Your LTL Shipment
Use the full freight class, density, pallet, and linear-feet tools for the next stage of shipment planning.
Freight Class Calculator
Estimate class from finished packaged dimensions, weight, and density.
Freight Density Calculator
Calculate cubic feet and pounds per cubic foot.
Pallet Freight Calculator
Plan pallet dimensions, shipment weight, density, and configuration.
Freight Linear Feet Calculator
Estimate trailer-space usage for pallets and non-stackable freight.
Freight classes shown on this page are density-based estimates for shipment planning. Actual classification may also depend on value, handling requirements, liability, stowability, dimensions, and applicable commodity-specific provisions. Confirm the final freight class with your carrier, broker, or official NMFC resources before shipping. NMFC® is a registered trademark of the National Motor Freight Traffic Association, Inc. FreightClassCalculator.tools is an independent calculator and is not affiliated with, endorsed by, or licensed by NMFTA.