Calculate your shipment's density and estimated freight class instantly.
Shipment Estimation Results:
Freight Class: —
Note: This is an estimate based on density. Carriers may also consider stowability, handling, and liability.
function calculateFreightClass() {
var length = parseFloat(document.getElementById('shipLength').value);
var width = parseFloat(document.getElementById('shipWidth').value);
var height = parseFloat(document.getElementById('shipHeight').value);
var weight = parseFloat(document.getElementById('shipWeight').value);
var resultBox = document.getElementById('freightResultBox');
var classOutput = document.getElementById('classOutput');
var densityOutput = document.getElementById('densityOutput');
if (!length || !width || !height || !weight || length <= 0 || width <= 0 || height <= 0 || weight = 50) { freightClass = "50"; }
else if (density >= 35) { freightClass = "55"; }
else if (density >= 30) { freightClass = "60"; }
else if (density >= 22.5) { freightClass = "65"; }
else if (density >= 15) { freightClass = "70"; }
else if (density >= 13.5) { freightClass = "77.5"; }
else if (density >= 12) { freightClass = "85"; }
else if (density >= 10.5) { freightClass = "92.5"; }
else if (density >= 9) { freightClass = "100"; }
else if (density >= 8) { freightClass = "110"; }
else if (density >= 7) { freightClass = "125"; }
else if (density >= 6) { freightClass = "150"; }
else if (density >= 5) { freightClass = "175"; }
else if (density >= 4) { freightClass = "200"; }
else if (density >= 3) { freightClass = "250"; }
else if (density >= 2) { freightClass = "300"; }
else if (density >= 1) { freightClass = "400"; }
else { freightClass = "500"; }
resultBox.style.display = 'block';
classOutput.innerHTML = "Estimated Freight Class: " + freightClass;
densityOutput.innerHTML = "Total Volume: " + cubicFeet.toFixed(2) + " cu ft" +
"Density: " + density.toFixed(2) + " lbs/cu ft";
}
Understanding Freight Class and NMFC Density
If you are shipping Less Than Truckload (LTL), determining your freight class is the single most important step in getting an accurate shipping quote and avoiding costly "re-weigh" or "re-class" fees from carriers. Freight class is a standardized shipping industry pricing classification established by the National Motor Freight Traffic Association (NMFTA).
What is Freight Class?
Freight class is a number ranging from 50 to 500 that categorizes commodities based on their "transportability." There are 18 different classes. A lower class (like Class 50) represents items that are very dense, hard to damage, and easy to handle (like steel bolts). A higher class (like Class 500) represents items that are very light relative to their size, fragile, or difficult to stow (like bags of ping pong balls or expensive kayaks).
How the Calculator Works: The Density Factor
While the NMFTA considers four factors (Density, Stowability, Handling, and Liability), density is the primary driver for most shipments. Density is calculated by dividing the total weight of the shipment by its total volume in cubic feet.
The Calculation Steps:
Measure: Record the length, width, and height of your shipment in inches (including pallets or packaging).
Calculate Volume: Multiply L x W x H to get cubic inches.
Convert to Cubic Feet: Divide the total cubic inches by 1,728.
Determine Density: Divide the weight of the shipment (in pounds) by the cubic feet.
Freight Class Density Table
Density (lbs per cubic foot)
Freight Class
Greater than 50
50
15 to 22.5
70
9 to 10.5
100
5 to 6
175
Less than 1
500
Example Calculation
Imagine you are shipping a pallet of boxed electronics components:
Dimensions: 48″ L x 40″ W x 45″ H
Weight: 400 lbs
Volume: (48 x 40 x 45) = 86,400 cubic inches
Cubic Feet: 86,400 / 1,728 = 50 cubic feet
Density: 400 lbs / 50 cu ft = 8 lbs per cubic foot
Result: Based on the density of 8, this shipment is Class 110.
Frequently Asked Questions
What happens if I get the class wrong?
If you list the wrong freight class on your Bill of Lading (BOL), the carrier's inspectors will likely catch the discrepancy at the terminal using "dimensioners." They will then issue a "Reclassification" invoice, which often includes the higher shipping rate plus an administrative fee (usually between $25 and $75).
Does every item have a density-based class?
No. Some items have a "fixed class" regardless of density. For example, some machinery or chemicals have a specific NMFC code that dictates a permanent class. Always check the NMFC book or consult with your broker for specialized items.