Overview

When shipping inventory to Amazon fulfillment centers via less-than-truckload (LTL) carriers through Amazon's Partnered Carrier program, sellers must assign the correct freight class to their shipments. Freight class determines shipping costs and handling requirements, making it one of the most important decisions in the inbound shipping workflow. Choosing the wrong freight class can lead to reclassification fees, delivery delays, or unexpected cost increases.

Key Points / What Sellers Need to Know

• Freight class is density-based — Amazon's partnered carrier program uses the National Motor Freight Classification (NMFC) system, where freight class is primarily determined by the density of your shipment (weight relative to volume).
• Density calculation matters — To estimate your freight class, divide the total shipment weight (in pounds) by the total cubic feet of space it occupies. Higher density generally means a lower freight class and lower shipping cost.
• Classes range from 50 to 500 — Freight classes span from class 50 (heaviest, most dense freight) to class 500 (lightest, least dense freight). Most Amazon FBA shipments fall between class 77.5 and class 200.
• Incorrect classification triggers adjustments — If the carrier determines that your shipment's actual freight class differs from what you declared, they may reclassify it and charge you the higher rate, sometimes with additional fees.
• Pallet dimensions and weight are inputs — You need accurate measurements of each pallet's length, width, height, and weight to calculate density and select the appropriate freight class.

How Freight Class Is Determined

Freight class under the NMFC system considers four primary factors: density, stowability, handling difficulty, and liability. For most standard Amazon FBA shipments consisting of boxed consumer products on pallets, density is the dominant factor. To calculate density, measure each pallet's dimensions in inches, convert to cubic feet (length × width × height ÷ 1,728), and then divide the pallet weight in pounds by the cubic footage. The resulting pounds-per-cubic-foot figure maps to a specific freight class. For example, shipments with a density of 35 pounds per cubic foot or higher typically qualify for class 65, while shipments at 6 to 8 pounds per cubic foot fall into class 125.