Dunnage is anything you put in a carton to stop the contents moving; void fill is the part of it that occupies empty space, and cushioning is the part that absorbs a drop. Carriers publish how much of it they expect, UPS asking for at least two inches on every internal face and FedEx asking for two to three inches on all six sides, and the gap between those numbers and what most sellers actually use is where damage claims come from.
Give the calculator the packed carton and it returns five live services on your lane.
Vendors use dunnage, void fill and cushioning interchangeably, which is why people buy the wrong thing. Separating them takes one sentence each.
A well-packed carton usually needs two of the three. Something soft against the product, something bulky in the leftover corners, and in the fragile case a second carton around the lot. Which of those you skip is a decision about how much a replacement costs you.
Each is a minimum against the wall rather than a total across the box, so a product needs that clearance on the bottom and the top as well as the four sides. UPS goes further for the two-box method, asking for an outer box six inches greater in depth, width and length than the inner one and an additional three inches of cushioning around the inner box. FedEx phrases the same idea as a second box at least six inches longer, wider and deeper. The double boxing page prices what those six inches do to a rate.
USPS approaches it from the other end, saying nothing about inches and everything about closure, asking for enough two-inch-wide packing tape to close and secure all seams and telling shippers not to wrap a box in string, cord or twine because it gets caught in sorting equipment. Read on usps.com, 2026-07-28.
Every filler is cheap. What separates them is what they do when the box lands on a corner, and what the carrier guidance says about each one.
| Material | Best at | Listed price | Cost per unit |
|---|---|---|---|
| Loose fill peanuts, Uline S-1564 | Filling irregular gaps around light goods | $24 per 12 cu ft bag | $2.00 per cu ft |
| Inflatable pillows, Uline S-13698 | Fast void fill with no dust or static | $101 per 250-bag carton | $4.04 per cu ft |
| Crumpled kraft paper, Uline S-3574 | Dense fill and surface wrap in one material | $32 per 18 in x 1,200 ft roll | $0.027 per ft |
| Air-cellular bubble roll, Uline S-3927P | The layer against the product itself | $49 per 12 in x 750 ft roll | $0.065 per ft |
Void fill is priced by the cubic foot, and so is the empty space it replaces, except the carrier charges considerably more for it. We ran the identical 5 lb load in three cartons on one lane.
| Carton, outer inches | Actual weight | Cheapest service returned | Price |
|---|---|---|---|
| 12 x 10 x 6 | 5 lb | UPS Ground Saver | $13.52 |
| 18 x 14 x 10 | 5 lb | UPS Ground Saver | $20.50 |
| 24 x 18 x 14 | 5 lb | UPS Ground | $36.75 |
Nothing about the contents changed across those three rows. The biggest carton cost 2.7 times the smallest for the same five pounds, a $23.23 gap, which at the listed price above buys roughly eleven cubic feet of loose fill. The lesson is not to skimp on fill, it is to buy the smallest carton that still leaves your two inches, then fill it properly.
Two related pages go deeper. Loose fill covers the settling behaviour and the corrugated-pad fix, and the wrap comparison covers what goes against the product surface.
Dunnage is any material added to a shipment to keep the contents from moving, including void fill, cushioning, corrugated pads, foam end caps and pallet bracing. Void fill and cushioning are subsets of it, one occupying empty space and the other absorbing impact.
UPS asks for at least two inches of appropriate cushioning material against the corners, sides, top and bottom of the container, and FedEx asks for 2 to 3 inches of cushioning on all six sides. Both were read on the carriers own sites on 2026-07-28.
Seal the carton, then rotate it slowly through every orientation and listen. Any knock or slide means the load can still travel inside the box, and the fill needs topping up until the carton goes silent under the same test.
Only if it makes you buy a bigger box. The same 5 lb load quoted $13.52 in a 12 by 10 by 6 inch carton and $36.75 in a 24 by 18 by 14 inch one from Newark, NJ 07102 to Atlanta, GA 30303 on 2026-07-28. Fill itself runs about two dollars a cubic foot.