Most ecommerce orders belong in the smallest package that gets the product there intact. For soft, unbreakable goods that is a poly mailer. For small items that can take a knock but not a crush, a padded mailer. For anything fragile, heavy or made of several pieces, a corrugated box with two to three inches of cushioning on every side. Get that choice right and the two other decisions, whether to pay for branded packaging and what to expect a 3PL to pack with, get much easier.
The reason the choice matters more than it looks is postage. Carriers can bill a package on its dimensional weight whenever that works out higher than its actual weight, so a box that is two inches too big in each direction can be billed as if it weighed several pounds more than it does. It is worth understanding that mechanism before you buy a single case of boxes.
Which packaging fits which product
Product | Pack it in | Why |
|---|---|---|
Apparel, textiles, soft goods | Poly mailer, or a paper mailer if recyclability matters to your customers | Nothing to break, the mailer adds almost no weight, and a mailer packed flat holds far less volume than a box, so there is far less air to be billed for |
Small, flat, sturdy items (books, cards, phone cases, packaged accessories) | Padded or bubble-lined mailer, or a rigid cardboard mailer for anything that must not bend | Cushions against drops and edge hits without the postage and storage cost of a box |
Fragile items (glass, ceramics, candles, cosmetics in glass) | Corrugated box with cushioning on all six sides | Needs a crush-resistant shell and space for padding; see how to ship fragile items for the full method |
Heavy or dense items (supplements in bulk, tools, cast goods) | Single-wall corrugated for most, double-wall when the weight or value warrants it | The box has to hold its shape under its own contents and whatever gets stacked on top |
Multi-item orders, kits, subscriptions | Mailer box or corrugated shipper sized to the typical order | Keeps items from grinding against each other, and the box doubles as the presentation |
Liquids and anything that can leak | Sealed inner bag or absorbent wrap inside a box | A leak ruins the label, the shipment and sometimes the carrier's other packages |
The table is a starting point, not a rule. A boxed product that already has a sturdy retail carton may only need a poly mailer around it, and a low-value fragile item may be cheaper to replace occasionally than to over-pack every time. The test is simple: what does it cost when this item arrives damaged, and how much packaging does it take to make that rare?
Poly, padded or paper mailer
Poly mailers are the default for anything soft. They weigh almost nothing, shrug off rain and conveyor grime, and they store flat, so a case of them takes far less shelf space than boxes. Plain ones are cheapest; bubble-lined versions add a layer of padding for small items that shouldn't be bounced around; expansion mailers have gusseted sides for thicker orders like a hoodie or a pair of jeans.
Paper mailers, padded or plain, trade some water resistance for easier recycling and a more natural look. They cost more per unit than plain poly and are heavier, but for a brand whose customers care about materials they are the honest middle path between poly and a box. The materials side of that decision has its own page: eco-friendly packaging materials.
Whatever you pick, size the mailer to the folded product. A mailer that is far too big flaps in transit, invites tearing at the seal, and looks careless when it arrives. Aim for the fewest sizes that cover your catalogue, often two or three.
When a box is the right call
A box earns its cost when the product can be crushed, when it needs cushioning that a mailer can't hold in place, or when the order is heavy enough that a bag would split. There are three kinds of box, and only one of them is a shipping container on its own.
- Paperboard folding cartons are the thin cardboard boxes products come in on a retail shelf. They protect against scuffs, not drops, and ship inside something else.
- Rigid boxes are the heavy, non-folding boxes used for premium gifts, electronics and cosmetics. They present well and resist crushing, but they are expensive, take a lot of shelf space, and still usually travel inside a corrugated shipper.
- Corrugated boxes have a fluted layer between two liners, which is what gives them crush strength. Single-wall handles most parcels. Double-wall is for heavy items, fragile contents, or anything that will be stacked. Mailer boxes, the fold-and-tuck style with a lid that opens like a drawer, are corrugated too, just lighter and designed to be seen when opened.
Right-sizing matters more with boxes than with anything else, because a box is where the postage math turns against you. Measure your three or four most common order shapes, pick the smallest standard box that leaves room for cushioning, and resist the urge to stock one big box that fits everything. It will fit everything, and whenever its dimensional weight comes out above the actual weight, you will pay for the air around it.
What packaging does to postage
Carriers price parcels on whichever is greater: the actual weight, or a dimensional weight worked out from the box's volume. Length times width times height in inches, divided by a divisor, rounded up to the next pound. All three major US carriers now use 139 as the standard divisor, though the details differ in ways that matter for a small brand:
- USPS applies dimensional weight to Ground Advantage and Priority Mail parcels only when they exceed one cubic foot, 1,728 cubic inches, so a box up to 12 by 12 by 12 inches ships on actual weight. Above that, the volume is divided by 139 (DMM 133.1.4 for Ground Advantage, DMM 123.1.3 for Priority Mail). USPS also adds nonstandard-size fees for parcels longer than 22 inches or larger than two cubic feet.
- UPS can apply dimensional weight to any package, with no size threshold, and the divisor depends on how you pay: 139 on Daily Rates (an account with negotiated or published daily pricing) and 166 on Retail Rates at a UPS Store counter (UPS dimensions and weight).
- FedEx uses 139 and charges the greater of dimensional or actual weight on every package (FedEx dimensional weight).
Here is what that does to a four-pound order. In a 12 by 10 by 8 inch box, 960 cubic inches, USPS bills the actual four pounds because the box is under a cubic foot. UPS on Daily Rates and FedEx divide 960 by 139 and bill seven pounds. Move the same order into a 14 by 12 by 12 inch box, 2,016 cubic inches, and every carrier now bills by volume: 15 pounds at a 139 divisor, 13 pounds at UPS retail. Nothing about the product changed. The box did.
Mailers help here because a mailer packed flat holds far less volume than a box, but they are not exempt. UPS and FedEx run the same calculation on a mailer as on a box, and USPS applies its one-cubic-foot test to the mailer's packed dimensions like any other parcel. What the math produces depends entirely on how the filled mailer measures. As one illustration, a 10 by 13 inch mailer packed two inches thick is 260 cubic inches, which rounds up to two pounds at a 139 divisor; pack the same mailer thicker and the figure climbs with it. Measure a few of your own packed mailers and run the numbers rather than assuming. The practical point is that a thin mailer has far less air in it to pay for than the 14 by 12 by 12 box above, and that is why the first question when postage looks high is not "which carrier" but "which box".
One related question comes up constantly: whether a poly mailer counts as a large envelope at USPS and gets the cheaper flat price. Only if it meets the standards for a flat, which means no more than three quarters of an inch thick, flexible, and of uniform thickness with the contents unable to shift more than two inches (DMM 201.4). A folded T-shirt in a mailer usually fails the thickness or uniformity test, so it is priced as a package. Treat the parcel price as the real one and the flat price as a bonus if your product happens to qualify.
Cushioning and void fill
Cushioning stops the product moving and absorbs impact; void fill just stops it moving. For fragile items, FedEx's packing guidance is to allow two to three inches of cushioning on all six sides, and that figure is a good one to design your box sizes around. The common options:
- Kraft paper, crumpled or machine-pleated, is cheap, recyclable and fine as void fill for sturdy items. It compresses under a heavy product, so it is weak protection for anything fragile.
- Air pillows are light and take up volume for very little weight, which makes them ideal for filling space in a box without adding postage. They offer little resistance to a sharp impact.
- Bubble wrap, or recycled-content bubble, is the workhorse for fragile items: wrap the item, then fill the remaining space so nothing shifts.
- Foam, in sheets, pouches or molded inserts, is the usual choice for glass, electronics and high-value goods, where protection shaped to the item matters more than the price of the fill.
A shake test is the fastest check: close the box, shake it, and if you can hear or feel the product move, add fill. If a product keeps arriving damaged despite good cushioning, the problem is usually the box, which is too big, too weak or reused one time too many.
Branded or stock packaging
Branded packaging means anything printed or made for you: custom boxes, printed mailers, branded tape, tissue, inserts. Stock packaging is the plain brown box or grey mailer any supplier sells by the case. The honest trade-off:
- Branded carries setup costs and is priced by quantity. Custom printing has to be set up for each run, so suppliers set minimum order quantities and quote a lower per-unit price as the run gets longer. The smaller your run, the more of that setup cost lands on each order, so get a quote at the quantity you would actually buy and compare it with the stock equivalent.
- Branded packaging is inventory. Every size you print has to be forecast, bought ahead, stored and counted. If a 3PL packs for you, ask whether custom packaging is stored and billed as inventory, because at most warehouses it is.
- A printed outer box advertises what's inside. For high-value goods left on a doorstep, a plain shipper with the branding inside draws less attention. For a subscription or gift product, the outer print is part of what the customer is paying for.
- Start with branding on the inside. Printed tissue, a sticker, a branded insert card, or a roll of printed kraft tape on a stock box makes the delivery feel considered without committing to a custom-printed carton, and each is easy to price against one on a supplier quote. Water-activated kraft tape, printed or plain, also makes a tamper-evident seal, which is a practical benefit on top of the cosmetic one.
If you are deciding whether branded packaging pays, treat it as an experiment rather than a conviction. Run a few hundred orders in each, then compare the numbers you actually have: damage rate, packaging cost per order, postage per order (a custom box that is slightly larger can cost more in postage than it does in printing), and repeat purchase rate if you can attribute it. Don't take anyone's word for how much unboxing lifts conversion. Measure it on your own orders.
Unboxing without overspending
The unboxing moment is the one time your brand is physically in the customer's hands, and it is worth a little thought. It does not need to be expensive. The order arriving undamaged and on time is most of it. After that, the things customers notice are a clean, easy-to-open package, the items arranged rather than tossed, a packing slip that doubles as a thank-you, and one small extra: a card, a sticker, a sample. Our guide to what a packing slip should include covers the one insert every order should carry anyway.
Keep the gestures proportionate to the price of the product and the margin on the order. Tissue paper and a card in a stock mailer can feel more generous than an elaborate box that clearly cost more than the item inside it.
What a 3PL packs your orders in
The questions to ask any fulfillment company are the same ones you'd ask yourself: what packaging comes standard, whether it is included in the per-order price or billed per box and mailer, whether they will use your custom packaging and how they charge to store it, and how they handle inserts and packing slips. Ask who files the carrier claim when a package arrives damaged, too.
At Simpl, packaging is included in the flat per-order rate along with picks, packing and postage, starting at $7 per order. Our stock packaging is recycled mailers, recycled bubble and standard boxes, and we source specific eco materials on request. If you want your own branded packaging used, or packing slips and marketing inserts included with each order, ask us; both are handled on request. Gift wrapping and handwritten notes are offered as well, and for apparel brands we can poly-bag each garment as an add-on service. If a carrier damages or loses a package we shipped, we file the claim. The ecommerce fulfillment and pricing pages have the rest of the detail.