How do I calculate freight class from density?

Density (PCF) = total weight in pounds divided by volume in cubic feet. Volume = length x width x height in inches divided by 1728. Match the density to the standard 13-bracket table: under 1 PCF is class 400, 8 to 10 PCF is class 100, 50+ PCF is class 50.

Why did the carrier change my freight class and charge more?

Carriers reweigh and remeasure shipments. If the actual dimensions or weight differ from what you declared, they reclassify (reclass) and bill the difference. Accurate dimensions, weight, and piece count prevent reclass fees.

Freight Class Calculator — Estimate LTL Class by Density

Length

Width

Height

Weight / unit

Pieces

Total volume

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cu ft

Density

—

PCF (lb/ft³)

Est. Class

—

by standard density

⚠️ Density-based estimate only. Some commodities have special NMFC classifications that do not follow density — final class depends on your NMFC code and the carrier. For multiple pieces, enter weight per unit and piece count.

What Is Freight Class?

Freight class is a standardized number from 50 to 500 (defined by the NMFC system) that determines your LTL shipping cost. It is based mainly on density, plus stowability, handling, and liability.

Rule of thumb: denser freight = lower class = lower cost. Light, bulky freight takes up space, so it gets a higher class and costs more.

The 18 classes are: 50 · 55 · 60 · 65 · 70 · 77.5 · 85 · 92.5 · 100 · 110 · 125 · 150 · 175 · 200 · 250 · 300 · 400 · 500

Standard Density-to-Class Chart

Most density-graded freight uses this chart. The calculator above is based on it.

Density (PCF)	Class	Density (PCF)	Class
< 1	400	12 – 15	85
1 – 2	300	15 – 22.5	70
2 – 4	250	22.5 – 30	65
4 – 6	175	30 – 35	60
6 – 8	125	35 – 50	55
8 – 10	100	≥ 50	50
10 – 12	92.5

About Your NMFC Number

An NMFC number is a commodity code (5–6 digits) that identifies exactly what you are shipping. Some commodities have a fixed class; others are graded by density. Provide your NMFC number when booking so the carrier classifies correctly.

Not sure which NMFC applies to your product? Use our free lookup tool: NMFC Lookup →

Avoid These Mistakes (They Cause Reclass Fees)

Inaccurate dimensions or weight — carriers reweigh and remeasure. Any mismatch triggers a reclass and a bill for the difference. Measure to the outermost edge (including the pallet) and include packaging weight.

Forgetting piece count — multi-piece shipments use total volume and total weight. Using a single piece can throw density off by 10x and get the class completely wrong.

Not providing an NMFC number — classification is most accurate with an NMFC number. Without one, only a density estimate is possible, and borderline freight is often reclassified by the carrier.

Treating hazmat as general freight — hazardous materials have their own classification and declaration requirements. Hazmat Guide →

FAQ

Are freight class and NMFC the same thing?

No. The NMFC number identifies what the commodity is; the freight class (50-500) is the billing tier. NMFC number + density determine the class.

What if my density falls right on a bracket edge?

Edge values go to the “greater-or-equal” bracket (e.g. exactly 10.0 PCF falls in the 10-12 bracket). Round dimensions and weight up to whole numbers.

Is the calculator’s class guaranteed?

It is a standard density-based estimate. Some commodities have special NMFC classifications that do not follow density — the final class depends on your NMFC code and the carrier.

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