Freight Class 50 vs 70 Density Requirements

The Short Answer

Freight Class 50 items are extremely dense (>50 lbs per cubic foot), like steel nuts, bolts, or ingots. They are the cheapest to ship per pound.

Freight Class 70 items are standard density (15-22.5 lbs per cubic foot), like boxed paper, car engines, or computers. A Class 70 shipment typically costs about 40-50% more per pound than a Class 50 shipment.

Understanding the Core Concept

In LTL (Less Than Truckload) shipping, carriers don't just charge by weight—they charge by "shipability." The National Motor Freight Classification (NMFC) system assigns a "Class" from 50 (clean, heavy, easy to handle) to 500 (light, fragile, expensive). This system creates a standardized way for carriers to price the risk and opportunity cost of filling their trailers.

The Density Spectrum:

Class 50 (The Brick): Fits on a standard pallet, extremely heavy, hard to damage. Carriers love this freight because it ballasts their trailer, providing a lower center of gravity which is safer. Because it is desirable, it is the cheapest class.
Class 70 (The Box): Standard consumer goods. Fits well, stacks well, decent weight. This is the "baseline" or "average" freight class. Think of auto parts, boxed furniture, or dry food goods.

Why it Matters: Misclassifying your freight is a disaster. If you declare Class 50 to get a cheap rate, but the carrier re-weighs/re-measures it as Class 70, you will be hit with a "Reclassification Fee" (often $75-$150) plus the difference in rate. This can double your shipping bill instantly.

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The Formula Breakdown

Density Calculation

Weight (lbs) / Volume (ft³)

Volume = (L x W x H in inches) / 1728

Step 1: Calculate Cubic Feet
Measure the handling unit (including the pallet!). Do not just measure the boxes ON the pallet. The carrier charges you for the wood too.
Example: 48" x 40" x 48" Pallet.
(48 x 40 x 48) = 92,160 cubic inches.
92,160 / 1728 = 53.33 cubic feet.

Step 2: Calculate Density (PCF)
Divide total weight by cubic feet.
Scenario A: Weight = 2,800 lbs. Density = 2800 / 53.33 = 52.5 PCF. Since this is > 50 PCF, it automatically qualifies for Class 50 (or potentially even lower/cheaper density-based commodity rates).
Scenario B: Weight = 1,000 lbs. Density = 1000 / 53.33 = 18.75 PCF. This falls squarely into the Class 70 bucket (15-22.5 PCF).

The range for Class 50 is strictly "Heavy". The range for Class 70 is "Standard". If you are on the borderline (e.g., 22.4 PCF), slightly shrinking your pallet height could bump you into the next cheaper class (Class 65 or 60).

Real World Scenario

A manufacturer ships industrial pumps.
Weight: 1,150 lbs.
Pallet Dims: 48x40x50 inches (55.5 cubic feet).

Current State

Density: 1150 / 55.5 = 20.7 PCF.

Freight Class: 70.

Rate: $450.00

Optimization

Strategy: Used a shorter pallet or double stacked?

No, add 100 lbs of heavy spare parts to the same pallet.

New Weight: 1250 lbs. Density: 1250 / 55.5 = 22.52 PCF.

New Class: 65?

Wait, a heavier pallet is cheaper?
Sometimes, YES. By increasing the density from 20.7 to 22.52, you cross the threshold from Class 70 to Class 65 (if your carrier uses granular breaks). While the weight went up, the rate per pound went down.

Note: Always check specific carrier tariffs rules before "adding weight" to save money. This strategy is called "Bumping" or "Declaration of Higher Density," but it is only legal if the NMFC code specifically allows for it. Do not just throw bricks on a pallet unless you are selling bricks.

Strategic Implications

1. The "Pallet Overhang" Killer
If your boxes overhang the pallet by 2 inches on each side, your 48x40 footprint becomes 52x44.
Old Volume: 55.5 cubic feet.
New Volume: (52x44x50)/1728 = 66.2 cubic feet.
Density drops from 20.7 PCF to 17.3 PCF. You just made your freight less dense, potentially bumping it into a more expensive class, AND you are paying for more cubic feet. Eliminate overhang at all costs. Overhang also drastically increases damage rates, which carriers hate.

2. FAK (Freight All Kinds)
Large shippers negotiate an "FAK" agreement. For example, "All freight from Class 50 to Class 100 shall be rated at Class 70." This allows you to ship light, bulky items (that should be Class 100) at the cheaper Class 70 rate. This is the single most powerful negotiation lever in LTL contracts. If you ship mixed commodities, ask for an FAK 85 or FAK 70.

3. The "Do Not Stack" Cone
If you place a "Do Not Stack" cone on a pallet, you are effectively claiming the vertical space to the ceiling of the trailer (96-108 inches). Some carriers will re-rate your shipment as if it were 96 inches tall, destroying your density calculation. Only use "Do Not Stack" if absolutely necessary.

Common Commodities by Class

Understanding which products typically fall into each class helps you anticipate carrier behavior and negotiate better rates. Here are typical examples:

Class 50 Examples: Steel coils, iron castings, concrete blocks, battery lead, metal stamping dies, and industrial steel nuts and bolts. These are the carriers' dream freight—heavy, compact, damage-resistant, and stackable. If you ship anything in this category, you should be paying the absolute lowest LTL rates available.

Class 70 Examples: Automotive parts (engines, transmissions), office furniture, cases of paper, canned food, and boxed machinery. These represent the "middle ground" of freight—neither particularly dense nor particularly light. Most business-to-business shipments fall somewhere in this range.

What if you're on the border? If your commodity's NMFC code allows for "density-based rating," you may be able to declare a more favorable class by proving your actual density with documentation. This is why accurate measurement and thorough NMFC research are essential—the same product in a smaller box might qualify for a cheaper class.

Actionable Steps

Measure Twice, Quote Once: Never guess dimensions. An extra inch of height can change your density enough to change your class. Use a laser measure. Accurate dimensions are your best defense against re-bills.
Challenge Re-Weighs: Carriers profit from re-weighs. If you get hit with a re-class fee, demand the "W&I Certificate" (Weight & Inspection). If they measured the pallet at 50" high but it's really 48", fight it. You will win if you have photos.
Use a Density Calculator: Don't do math in your head. Use the tool on this site to confirm your PCF (Pounds per Cubic Foot) before booking the shipment. Print the calculation and tape it to the BOL (Bill of Lading) as proof of your math.

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Frequently Asked Questions

PCF stands for 'Pounds per Cubic Foot'. It is the unit of measurement for density. Formula: Total Weight / Total Volume (in ft³).

Generally, no. FTL is usually priced by the mile or flat rate lane. Freight Class is specifically an LTL (Less Than Truckload) concept used to standardize pricing across different commodities sharing the same trailer.

Yes. Lower class numbers generally mean lower rates. Class 50 is the 'cheapest' standard class (e.g., steel, bricks). Class 500 is the most expensive (e.g., ping pong balls, assembled lamp shades).

Class 70 typically covers freight with a density between 15 and 22.5 lbs per cubic foot. This includes car engines, printed matter, and food items.

Yes, but be careful. The carrier will usually rate the entire pallet at the *highest* class on the pallet. If you mix Class 50 bricks with Class 200 light bulbs, you might pay Class 200 rates for the bricks. Separate them if possible.

Disclaimer: This content is for educational purposes only.