Introduction
Freight class determines how much you pay to ship items by LTL (less-than-truckload) carriers. The National Motor Freight Classification (NMFC) system assigns a class from 50 to 500 based on your shipment's density, which is its weight divided by its volume. A lower class means a lower shipping cost, and a higher class means a higher cost.
This Freight Class Calculator makes it simple to find your shipment's class. Just enter the length, width, height, and weight of your item, and the tool does the rest. It calculates the volume in cubic feet, finds the density in pounds per cubic foot (PCF), and matches it to the correct NMFC freight class. You can use US or metric units, and the calculator handles the conversion for you.
Knowing your freight class before you request a shipping quote helps you plan costs, avoid billing surprises, and compare carrier rates with confidence. Use the calculator below to get your result in seconds.
How to Use Our Freight Class Calculator
Enter your shipment's size, weight, and number of pieces below. The calculator will find your freight density and give you the correct NMFC freight class.
Unit System: Pick US/Imperial (inches and pounds) or Metric (centimeters and kilograms). If you switch units after typing in numbers, the calculator converts them for you.
Length: Type the length of one piece of your shipment. Use inches for US or centimeters for Metric.
Width: Type the width of one piece of your shipment. Use inches for US or centimeters for Metric.
Height: Type the height of one piece of your shipment. Use inches for US or centimeters for Metric.
Weight: Type the weight of one piece of your shipment. Use pounds for US or kilograms for Metric.
Number of Pieces: Type how many identical pieces are in your shipment. This must be a whole number of 1 or more.
Calculate: Click the Calculate button to see your results. You will get your estimated freight class, density in pounds per cubic foot, volume per piece, total volume, and total weight.
Reset: Click the Reset button to clear all fields and start over with the default values.
What Is Freight Class?
Freight class is a number assigned to shipments that move by LTL (less-than-truckload) carriers. The National Motor Freight Traffic Association (NMFTA) created 18 classes that range from class 50 to class 500. These classes help carriers decide how much to charge for shipping your goods.
How Is Freight Class Determined?
The most common way to find your freight class is by calculating density. Density is how much something weighs compared to how much space it takes up. You measure it in pounds per cubic foot (PCF). A heavy, small item has high density and gets a lower class number. A light, large item has low density and gets a higher class number. Lower class numbers mean lower shipping costs.
How to Calculate Density
First, multiply the length, width, and height of your shipment in inches. Divide that number by 1,728 to get cubic feet. Then divide the weight in pounds by the cubic feet. The result is your density in PCF. This calculator does all of that math for you instantly. If you need to determine the volume of irregularly shaped shipments or want to explore volumetric weight for air freight comparisons, those tools can also help with your logistics planning.
Why Freight Class Matters
Carriers use freight class to set their rates. If you pick the wrong class, you could get hit with extra fees or a reclassification charge. Knowing your correct freight class before you ship helps you get accurate quotes, avoid surprise costs, and plan your budget. It also helps you compare rates between different LTL carriers fairly. When planning your overall supply chain, understanding lead time alongside freight costs gives you a more complete picture. For parcel shipments, you can also estimate costs using our USPS shipping calculator or FedEx shipping calculator.
Things to Keep in Mind
Density is not the only factor that can affect freight class. Some items have a fixed class set by the NMFC code based on what the product actually is. Fragile, hazardous, or oddly shaped items may be assigned a higher class regardless of density. Always check the specific NMFC classification for your commodity when possible. This calculator gives you a density-based estimate, which works well for most standard shipments. For construction materials like concrete or steel, knowing the exact weight beforehand makes your freight class calculation more accurate.