Freight Class for Corrugated Boxes
Empty corrugated boxes ship flat for a reason. Knocked-down (KD) bundles, banded tight on a pallet, measured 8.4 lb/ft³, which is class 100 on the current NMFC scale. A single loose bundle measured 6.0 lb/ft³, class 125. The same boxes shipped erected measured 1.7 lb/ft³, which is class 300. Flat versus erected is almost the whole decision.
Shipping the packaging itself
Corrugated is the strange case where the freight *is* packaging — so its density is purely a function of its own state. Knocked down flat and banded into bundles, corrugated is sheets of board stacked face to face: reasonably dense, easy to pallet, easy to rate. Erected, the identical boxes become their end-use shape — containers of air — and their measured density collapses by an order of magnitude. No other commodity's class swings this hard on a handling decision that costs nothing.
Board weight matters too, in the quieter second order. Heavy double-wall and triple-wall board runs meaningfully more pounds per sheet than single-wall E-flute, so a pallet of KD industrial boxes can measure two classes denser than the same cube of KD retail mailers. When you quote mixed board grades as one shipment, the blended density is what counts — weigh the real pallet rather than extrapolating from last month's different mix.
Worked examples
Measured as the carrier sees them: the outside of the bundle or the loaded pallet, and the total weight.
Palletized KD bundles, tightly banded — class 100
Flattened box bundles stacked 45" high on a 48" × 40" pallet, 420 lb.
48 × 40 × 45 = 86,400 in³ ÷ 1,728 = 50.0 ft³. Density = 420 lb ÷ 50.0 ft³.
8.4 lb/ft³ → class 100 on the current NMFC scale — the well-shipped end of the corrugated range.
A single strapped bundle of 25 KD boxes — class 125
One banded bundle of flattened medium shippers, 30" × 24" × 12", 30 lb.
30 × 24 × 12 = 8,640 in³ ÷ 1,728 = 5.0 ft³. Density = 30 lb ÷ 5.0 ft³.
6.0 lb/ft³ → class 125. Loose single bundles rate worse than a consolidated pallet.
The same boxes shipped erected — class 300
Erected empty boxes filling a 48" × 40" × 48" gaylord, 90 lb.
48 × 40 × 48 = 92,160 in³ ÷ 1,728 = 53.3 ft³. Density = 90 lb ÷ 53.3 ft³ = 1.7 lb/ft³.
1.7 lb/ft³ → class 300 — far outside the typical range. Erected boxes are shipped air; keep them flat.
Bundle, band, and stack to the pallet's edge
The KD pallet is won or lost in the strapping. Tight bundles with aligned edges stack into a solid block; loose bundles pillow in the middle, round the stack's shoulders, and add measured inches that are pure air. Band bundles to consistent counts, stack them column-aligned to the pallet's footprint, and cap the top layer flat — a corrugated pallet built this way measures what the board actually is.
And never ship erected boxes if there is any alternative. Erected corrugated rates at the light-freight extremes — class 300 territory or worse — which can price the *empty boxes* above the freight cost of the goods they'll eventually carry. If a customer needs boxes pre-erected (some packing lines do), price that shipment knowingly, or quote the KD equivalent plus on-site erecting as the comparison.
Check your box shipment's class
Enter the bundle or pallet size and the total weight. For pallets, measure the stack at its widest and tallest points.
Density-based estimate. Some commodities carry a fixed NMFC class — check our freight class by commodity pages.
Estimated Freight Class
Density
9
lb/ft³
Volume
53.33
ft³
Weight
480
lb
8–10 lb/ft³ → Class 100
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 are corrugated boxes?
Flat, banded bundles on a pallet usually rate class 100 to 125 on the current NMFC scale. Single loose bundles sit at the high end of that range. Erected, empty boxes rate about class 300. Ask your carrier whether your box product has a specific NMFC listing.
What freight class are empty boxes?
Flattened and banded, empty corrugated typically measures 6–9 lb/ft³ → class 100–125 on the current NMFC scale, and tight palletized bundles do better still. Erected empty boxes measure 1–2 lb/ft³ → class 300. Flat versus erected is the entire game.
Does board grade change corrugated freight class?
Yes — double- and triple-wall board weighs substantially more per sheet than single-wall, so KD bundles of heavy board measure denser and can rate a class or two lower on the same cube. Weigh the actual mixed pallet when grades vary.
How should I palletize flattened boxes for the best class?
Consistent banded bundle counts, edges aligned, columns stacked flush to the 48" × 40" footprint, flat top layer, tight strapping. The goal is a solid rectangular block — every pillowed bundle or rounded shoulder adds measured air.