function calculateFreightClass() {
var length = parseFloat(document.getElementById('freightLength').value);
var width = parseFloat(document.getElementById('freightWidth').value);
var height = parseFloat(document.getElementById('freightHeight').value);
var weight = parseFloat(document.getElementById('freightWeight').value);
var resultDiv = document.getElementById('freightResult');
if (isNaN(length) || isNaN(width) || isNaN(height) || isNaN(weight) || length <= 0 || width <= 0 || height <= 0 || weight <= 0) {
alert("Please enter valid positive numbers for all fields.");
return;
}
var cubicInches = length * width * height;
var cubicFeet = cubicInches / 1728;
var density = weight / cubicFeet;
var freightClass = 50;
if (density < 1) freightClass = 500;
else if (density < 2) freightClass = 400;
else if (density < 3) freightClass = 300;
else if (density < 4) freightClass = 250;
else if (density < 5) freightClass = 200;
else if (density < 6) freightClass = 175;
else if (density < 7) freightClass = 150;
else if (density < 8) freightClass = 125;
else if (density < 9) freightClass = 110;
else if (density < 10.5) freightClass = 100;
else if (density < 12) freightClass = 92.5;
else if (density < 13.5) freightClass = 85;
else if (density < 15) freightClass = 77.5;
else if (density < 22.5) freightClass = 70;
else if (density < 30) freightClass = 65;
else if (density < 35) freightClass = 60;
else if (density < 50) freightClass = 55;
else freightClass = 50;
document.getElementById('classOutput').innerHTML = "Class " + freightClass;
document.getElementById('densityOutput').innerHTML = density.toFixed(2) + " lb/ft³";
document.getElementById('volumeOutput').innerHTML = cubicFeet.toFixed(2) + " ft³";
resultDiv.style.display = 'block';
}
Understanding LTL Freight Class
Freight class is a standardized shipping category established by the National Motor Freight Traffic Association (NMFTA). It is designed to provide a uniform pricing structure for Less-Than-Truckload (LTL) shipments. There are 18 different classes, ranging from Class 50 (the least expensive) to Class 500 (the most expensive).
How is Freight Class Calculated?
While freight class is determined by four factors—density, stowability, ease of handling, and liability—density is the primary driver for most general commodities. Our calculator uses the density-based formula:
- Step 1: Multiply Length x Width x Height in inches to get total cubic inches.
- Step 2: Divide cubic inches by 1,728 to convert to cubic feet.
- Step 3: Divide the weight of the shipment by the total cubic feet to find the density (Pounds per Cubic Foot – PCF).
- Step 4: Match the PCF against the NMFC density table to find the class.
Real-World Example
Imagine you are shipping a pallet of electronics that weighs 500 lbs. The pallet dimensions are 48″ x 40″ x 48″.
- Volume: 48 x 40 x 48 = 92,160 cubic inches.
- Cubic Feet: 92,160 / 1,728 = 53.33 cubic feet.
- Density: 500 lbs / 53.33 cu ft = 9.37 PCF.
- Based on the density table, a density of 9.37 PCF falls into Freight Class 100.
Why Accuracy Matters
Providing an incorrect freight class on your Bill of Lading (BOL) can lead to "Re-weigh and Re-class" fees from the carrier. These adjustments can often double the original cost of the shipment. Using a freight class calculator helps you estimate shipping costs accurately and avoid unexpected invoices from carriers like FedEx Freight, Old Dominion, or XPO Logistics.
Pro Tip: Always include the weight of the pallet itself (usually 30-50 lbs) in your total weight calculation, as carriers charge for the total gross weight of the unit, not just the product inside.