What is NMFC? / 什么是NMFC？
NMFC (National Motor Freight Classification) is the standard system used by all LTL carriers in the U.S. to classify freight. Each commodity is assigned a Freight Class (50–500) that determines shipping rates.
NMFC（美国国家汽车货运分类标准）是所有美国LTL承运商统一使用的货物分类体系。每种商品对应一个 Freight Class（50–500），Class越高运费越贵。
4 Factors That Determine Freight Class / 决定货类的4个因素
📊 Density 密度
Weight ÷ volume (lbs per cubic ft). Higher density = lower class = lower cost.重量÷体积。密度越高，等级越低，运费越便宜。
🔧 Handling 搬运难度
How easy or difficult the freight is to handle. Fragile, odd shapes, or hazmat increase class.是否易碎、异形、危险品——搬运越困难，等级越高。
📦 Stowability 堆叠性
Can the freight be stowed with other items? Non-stackable or irregular items get higher class.是否可以和其他货物堆放？不可堆叠的货物等级更高。
💰 Liability 责任风险
Likelihood of damage, theft, or spoilage. High-value or perishable items get higher class.损坏、丢失、变质的风险。贵重品或易腐品等级更高。
Density vs NMFC: Which Takes Priority? / 密度和NMFC哪个优先？
⚠️ Important Rule / 重要规则
NMFC code always takes priority over density calculation. Density is only ONE of the four classification factors. Even if the density suggests a lower class, the carrier will classify based on the actual NMFC rules for that commodity — which may include handling, stowability, and liability factors that increase the class.
NMFC编码始终优先于密度计算。密度只是四个分类因素之一。即使密度建议较低的Class，承运商仍会按该商品的实际NMFC规则来分类——其中可能包含搬运、堆叠和责任等因素，从而提高Class。
Example / 举例： A shipment of glass panels might calculate to Class 70 by density alone, but because glass is fragile (high handling + high liability), its NMFC classification is Class 85–150. If you ship at Class 70, the carrier will reclassify and charge you the difference.
例如：一批玻璃板按密度可能算出Class 70，但因为玻璃易碎（搬运难度高+责任风险高），NMFC实际分类是Class 85–150。如果你按Class 70发货，承运商会重新分类并收取差价。
Best Practice / 最佳做法
1️⃣ Know your NMFC code — search it on this page or ask your supplier. This is the most reliable way.
查清你的NMFC编码——在本页搜索或向供应商确认，这是最可靠的方式。
2️⃣ If you don't have an NMFC code — our system will calculate class based on density. This works well for most standard cargo.
如果没有NMFC编码，系统会根据密度自动计算Class，对大多数标准货物够用。
3️⃣ Watch for exceptions — fragile, battery, liquid, loose/unboxed items may need a higher class regardless of density.
注意例外情况——易碎品、含电池、液体、裸装货物即使密度低也可能需要更高等级。
4️⃣ Accurate dimensions & weight matter most — if your measurements are accurate, reclassification risk is low.
尺寸和重量的准确性最重要——测量准确，被重新分类的风险就低。