Freight Class for Steel
Solid steel products almost always rate freight class 50, the lowest class, because steel weighs about 490 lb per cubic foot and even a loosely packed load stays far above 50 lb/ft³. For steel, the class is rarely the problem. Length is: LTL carriers add a charge per shipment once a piece reaches 8 feet, and XPO requires pipe, bars, rods and tubing to ship in a fully enclosed wooden crate.
How dense steel is
ASTM A615 lists a #4 reinforcing bar, half an inch across, at 0.668 lb per foot. Work that back and solid steel comes to about 490 lb per cubic foot (7,850 kg/m³), the figure engineers use for carbon steel. Class 50 starts at 50 lb/ft³, so a load would need to be about 90% empty space before solid steel fell out of class 50.
Hollow and fabricated steel is different. Shelving, racks, thin tube and welded frames enclose a lot of air, and they can measure far lower. Measure those loads as they will ship instead of assuming class 50.
Worked examples
Weights come from the 490 lb/ft³ steel figure and ASTM A615 bar weights. The crate size in the second example is an assumption; use your own.
Steel plate on a pallet — class 50
Four plates, each 48 × 40 × 1 in (544 lb at 490 lb/ft³), on a 37 lb GMA pallet: 8.75 inches high, 2,215 lb.
48 × 40 × 8.75 = 16,800 in³ ÷ 1,728 = 9.7 ft³. Density = 2,215 lb ÷ 9.7 ft³.
228 lb/ft³ → class 50. At this weight, check the pallet's load rating before the class.
Crated 20-foot rebar — class 50, plus a length charge
150 #4 bars, 20 feet long, at 0.668 lb per foot: 2,004 lb. Say the crate is 246 × 12 × 12 in and weighs 150 lb: 2,154 lb in all.
246 × 12 × 12 = 35,424 in³ ÷ 1,728 = 20.5 ft³. Density = 2,154 lb ÷ 20.5 ft³.
105 lb/ft³ → class 50. The length charge is the real cost: $5,240 at XPO or $1,514 at FedEx Freight, which may also refuse it.
Length charges for long steel
LTL carriers add a flat charge per shipment for long pieces, on top of the freight rate. XPO's rules tariff (Item 238, August 17, 2026) charges $460 when a handling unit is 8 to under 11 feet long, $925 from 11 to under 16 feet, $1,535 from 16 to under 20 feet and $5,240 at 20 feet or more.
FedEx Freight's tariff (Items 525 and 530) charges $375 for 8 to under 12 feet, then $775, $982 and $1,234 in steps up to 20 feet, and $1,514 at 20 feet or more. FedEx may also refuse any unit 12 feet or longer. For long bar and pipe, compare the LTL total with a flatbed quote before you book.
Crating bars, pipe and tube
XPO's tariff says that, under NMFC Rule 680 and its own policy, pipe, bars, rods and tubing of any length must be shipped in a fully enclosed, six-sided wooden crate. XPO can refuse uncrated loads of this kind. The crate protects the steel and the other freight on the trailer.
A crate adds weight and a little size, but at steel's density the load stays in class 50. Put the crate's real outside size and the total weight on the bill of lading, since the carrier will measure the crate, not the bars inside.
Check a steel shipment
Enter the pallet or crate's outside length, width and height, and the total weight. Solid steel will show class 50; hollow or fabricated steel may not.
Density-based estimate. Some commodities carry a fixed NMFC class — check our freight class by commodity pages.
Estimated Freight Class
Density
54.99
lb/ft³
Volume
53.33
ft³
Weight
2,933
lb
50+ lb/ft³ → Class 50
NMFC density scale (Docket 2025-1, effective July 19, 2025)
Free PDF includes a watermark. Pro removes it & adds your brand.
Estimates only — verify freight class/NMFC and chargeable weight with your carrier.
Uses the 13-tier NMFC density scale (Docket 2025-1). See the full freight class chart.
Frequently asked questions
What freight class is steel?
Class 50 for solid steel products such as plate, bar, coil and rebar, because they measure far above 50 lb/ft³. Hollow or fabricated steel, such as shelving or thin tube, can rate higher, so measure it.
What is the density of steel?
About 490 lb per cubic foot, or 7,850 kg/m³, for carbon steel. ASTM A615 bar weights, such as 0.668 lb per foot for a half-inch #4 bar, work out to the same figure.
How much does rebar weigh per foot?
Under ASTM A615: #3 is 0.376 lb/ft, #4 is 0.668, #5 is 1.043, #6 is 1.502 and #8 is 2.670.
Do LTL carriers charge extra for long steel?
Yes, per shipment. XPO charges $460 from 8 feet up to $5,240 at 20 feet or more. FedEx Freight charges $375 from 8 feet up to $1,514 at 20 feet or more, and may refuse units 12 feet or longer.
Does steel pipe have to be crated for LTL?
At XPO, yes: its tariff requires pipe, bars, rods and tubing of any length to ship in a fully enclosed, six-sided wooden crate, and it can refuse uncrated loads. Check your carrier's rule before you book.