Shipping used goods without losing money

Buy the label online, not at the counter

Before any of the rules below: the price at the post-office counter is rarely the cheapest way to pay for postage. Labels bought online, through the marketplace's own shipping flow or a carrier's website, are often cheaper for the same service. Compare before you buy, and print at home.

Three easy ways to lose money on shipping

Three mistakes are easy to make. Sellers offer "free shipping" they never priced into the listing. Sellers pick the wrong service for the item shape and pay more than they had to. Sellers skip insurance on something fragile and eat the loss when it breaks. None of these have a one-size-fits-all fix. A two-pound book and a thirty-pound floor lamp are different shipments; a cast-iron pan and a glass vase are different risk profiles.

What follows are general guidelines, not hard rules. The specifics will move with the item, the destination, and the value at stake.

Packaging the carriers already give you

The boring trick that's easy to miss: the carriers will hand you the boxes for free if you're using their service. USPS Priority boxes are free to order through usps.com and delivered to your door at no charge. UPS and FedEx have free packaging for their own services as well. Carriers will deliver bulk packaging to a residential address; you do not have to be a business.

Beyond carrier-provided packaging: reused Amazon and other delivery boxes (almost-free supply, just remove the old labels with a marker or a fresh address sticker), grocery-store paper for fill, used bubble wrap saved from your own deliveries. The packaging cost on most items can run close to zero if you're willing to keep a small box of supplies.

Flat-rate vs. calculated: pick by item shape, not item value

Calculated shipping (priced by weight plus distance) wins for most items because it scales with the actual cost. The buyer pays whatever it costs to ship to them; you don't have to guess. Flat-rate wins for a narrow band: heavy items in small boxes, where the actual weight would push calculated rates above the flat-rate price.

Rough rule: if your item is heavier than about 5 lbs and fits in a flat-rate box, run both rates side by side. Otherwise default to calculated. Using flat-rate for everything (especially light items in big boxes) can mean overpaying on every package, and that adds up.

The dimensional-weight gotcha

UPS and FedEx don't always charge by what your package weighs. For boxes that are big-but-light, both carriers calculate a "dimensional weight" (length times width times height divided by 139 for ground service in the US, as of April 2026), then bill on whichever number is higher: actual weight or dimensional weight. The math catches sellers off guard on items like pillows, lampshades, or anything packed in an oversized box.

Practical rule: if your item is light but the box is large, measure the outside dimensions and run the dimensional-weight math before you pick a carrier. USPS Ground Advantage and Priority Mail use dimensional weight only above 1 cubic foot, so for boxes under that threshold USPS often wins on light-but-bulky items. Above 1 cubic foot, UPS and FedEx will both apply the dimensional charge regardless. Knowing which side of the threshold your package sits on changes the cheapest carrier.

The free $100 insurance that's easy to forget

USPS Priority Mail includes $100 of declared-value coverage at no extra charge. UPS Ground includes $100 of declared-value coverage at no extra charge. Both have been baseline features for years; neither carrier markets them aggressively, so it's easy not to realize the coverage is already there.

That free $100 baseline is the entire reason the "under $100, skip the insurance" rule of thumb works. The insurance isn't skipped; it's already included in the rate. Above $100, USPS prices additional insurance in tiers: $4.50 for coverage up to $200, rising to $9.05 at $600, then $1.50 per $100 (or fraction) above that, per the USPS price list in effect since July 12, 2026. UPS publishes its own declared-value schedule; check it when you book. At that point the math becomes a per-shipment decision.

Heavy, fragile, awkward: when to charge, when to refuse

Some items eat your profit if you're not careful with them. Heavy items where shipping cost approaches half the sale price. Fragile items where insurance becomes mandatory. Awkwardly shaped items that don't fit standard boxes: lamps, framed art, sports equipment, anything with one long dimension.

Two answers depending on the math:

• Charge correctly. If shipping is going to cost $30, the buyer pays $30. Don't bury it in the item price; calculated shipping does this automatically and the buyer sees the real number before they commit.
• Local pickup only. When shipping would eat a big share of what the item sells for, "pickup only" in your local marketplace listing is often the right call. Less reach, but no shipping disaster on the back end.

Some items just shouldn't ship. A 50-pound piece of exercise equipment, a tall floor lamp with a fragile shade, an oversized framed print: the right marketplace for these is local. Knowing which items belong in that category saves you from one bad return that wipes out a month of small wins.

When shipping costs more than the item

Say you've got an $8 item and the cheapest label is $10. Before you list it, look at how often that exact item sells, and at what price. If you're fine sitting on something obscure and waiting, it can still sell. But think about what you're asking of the buyer: once shipping is added, they're paying more than double your asking price. It has to be worth their while.

So it comes down to how much demand there is for that particular thing, how long you're willing to sit with it, and whether listing, packing and shipping it is worth the effort to you. The general rule: is it cheap because nobody wants it, or cheap because it was never expensive in the first place?

Take an old desktop computer. It has some novelty to it, but it's now less powerful than the phone in your pocket, so it might be worth $40 instead of the $400 it once was. There may be someone out there who'd pay that $40, but they're few and far between, because the machine is obsolete: software that's no longer supported, on hardware that can't run modern programs. With something like that, your data matters more than the price. Take the drive out and deal with it properly (the $50 rule covers how), then donate or recycle the rest.

Now take a Funko Pop you paid $30 for that's worth $10 today. There's a decent chance it sells at $10, because there's still a market for it; collectors just aren't as excited about that model anymore, so its price came down. A collectible never had a function in the first place, so it can't go obsolete the way a computer does. The collectors' market is what keeps it relevant, and its price reflects that market. Cheap because the market cooled is a very different thing from cheap because nobody needs it anymore.

The recap, as a numbered list

1. Buy labels online and compare prices; the post-office counter is rarely the cheapest.
2. Order free Priority and UPS boxes from the carriers; never pay for packaging that the carrier hands out.
3. Default to calculated shipping. Use flat-rate only for heavy items in small boxes.
4. For light-but-large items, run dimensional weight before picking UPS or FedEx; USPS often wins under 1 cubic foot.
5. Trust the free $100 insurance baseline on Priority and UPS Ground. Pay for additional coverage only above $100.
6. When shipping would eat a big share of the price, sell locally or price for it.
7. Self-insure under $100, paid-insure over it. The threshold is regret, not math.
8. When shipping costs more than the item, ask whether it's cheap because nobody wants it, or because it was never expensive.

For the side of shipping that's about what you can't legally put in a box (hazmat, lithium batteries, restricted categories), the next read is what you can't (or shouldn't) sell online.