Packaging Optimization: Stop Shipping Air and Start Saving Money

A supplement company I worked with shipped vitamins in 12 by 10 by 8-inch boxes. The bottles fit, barely, with a mountain of air pillows filling the empty space. When we switched them to 9 by 7 by 5-inch boxes — actually sized for their product — they saved an average of 2.40 dollars per package. At 2,200 packages per month, that came out to 63,360 dollars in annual savings. Same product, same carrier, same destination. The only thing that changed was the box.

This is the reality of dimensional weight pricing: every cubic inch of empty space inside your box costs money. The carriers are not charging you for the weight of your product — they are charging you for the space your box occupies in their truck. And most e-commerce businesses are shipping boxes that are 20 to 40 percent larger than they need to be.

How Dimensional Weight Costs You Money

Dimensional weight is calculated by multiplying the length, width, and height of your box (in inches) and dividing by a carrier-specific factor — 139 for UPS and FedEx, 166 for USPS. The carrier charges you for whichever is greater: the actual weight or the dimensional weight.

A 12 by 10 by 8-inch box has a dimensional weight of about 7 pounds using the UPS/FedEx factor. If your product inside weighs 2 pounds, you are paying the 7-pound rate. Switch to a 9 by 7 by 5-inch box and the dimensional weight drops to about 2.3 pounds — now you are paying for the actual weight of your product instead of paying for empty air.

The cost difference per package ranges from one to four dollars depending on the carrier, service, and zone. On the surface, two dollars per package does not sound dramatic. But multiply it by hundreds or thousands of monthly shipments and the annual waste is staggering. Most businesses do not even realize they are overpaying because they never look at the DIM weight column on their carrier invoices.

The Right-Sizing Process

Right-sizing means matching your box dimensions to your product dimensions as closely as possible while leaving just enough room for cushioning material. The goal is not to eliminate packaging protection — it is to eliminate the empty space that serves no purpose except inflating your shipping cost.

Start by measuring your top-selling products and determining the minimum box size that holds each product with two inches of cushioning on every side. For many products, this means a box that is significantly smaller than what you are currently using. If your best seller is a 6 by 4 by 3-inch item, the ideal box is roughly 8 by 6 by 5 inches — not the 12 by 10 by 8-inch box you grabbed because it was the closest size on the shelf.

Most packaging suppliers offer custom box sizing at reasonable minimums. If you ship more than a few hundred packages per month, ordering boxes cut to your specific dimensions costs less per unit than buying standard sizes and pays for itself quickly through reduced DIM weight charges.

If custom boxes are not practical, stocking three to four standard box sizes and selecting the smallest one that fits each order is still a major improvement over using one-size-fits-all packaging. The five minutes it takes someone to choose the right box size for each order saves you money on every single shipment.

Poly Mailers vs Boxes

For products that are not fragile — clothing, fabric items, books in protective sleeves, stickers, accessories — poly mailers eliminate the dimensional weight problem entirely. Carriers measure poly mailers differently than boxes, and the flexible packaging conforms to the item rather than creating a rigid box of empty space.

A T-shirt shipped in a poly mailer weighs a few ounces and costs two to four dollars to ship. The same shirt in a small corrugated box might trigger a dimensional weight of two to three pounds and cost six to eight dollars. The poly mailer saves three to five dollars per shipment while providing adequate protection for non-fragile items.

Padded poly mailers add a layer of bubble protection and are suitable for items that need slight cushioning but not the structural rigidity of a box. Electronics in retail packaging, books, and small hard goods often ship safely in padded mailers.

Void Fill: Less Is Better

Void fill exists to prevent items from moving inside the box, not to fill every cubic inch of space. If you need a lot of void fill, your box is too big. The ideal amount of void fill is the minimum needed to immobilize the product and cushion it from the box walls.

Air pillows are the most efficient void fill by weight — they add almost nothing to the actual package weight while preventing movement. Kraft paper is inexpensive and recyclable. Packing peanuts work but customers hate them, and they tend to shift during transit, which means the product can settle to the bottom of the box with peanuts on top rather than surrounding it.

Foam-in-place systems that inject expanding foam around the product create custom cushioning for every package and eliminate nearly all wasted space. These systems cost several thousand dollars for the equipment but make sense for businesses shipping fragile or high-value items where both protection and space efficiency matter.

Measuring Your Opportunity

The fastest way to quantify your packaging waste is to audit ten to twenty of your most recent shipments. For each one, compare the actual weight to the billed weight (which is the greater of actual and DIM weight). If the billed weight consistently exceeds the actual weight, you are shipping air.

Calculate the difference between what you paid and what you would have paid at the actual weight rate. Multiply that per-package difference by your monthly volume, and you have your annual savings opportunity from right-sizing.

Shipping platforms like atoship show both actual weight and DIM weight for every shipment, making it easy to spot which products and box sizes are costing you the most in wasted dimensional weight charges. This data-driven approach lets you prioritize which packaging changes will have the biggest financial impact.