Amazon Buy Shipping: why Amazon wants you to use it
Buy Shipping is Amazon's postage store inside Seller Central: open an FBM order, click Buy Shipping, and Amazon quotes its negotiated rates across connected carriers, prints the label, and confirms the shipment with valid tracking in one step. The pitch isn't just convenience — it's protection. Ship a Buy Shipping label on time, and Amazon takes responsibility for delivery-related A-to-Z Guarantee claims: a buyer's 'never arrived' claim against an on-time Buy Shipping shipment generally doesn't count against your order defect rate.
That claim-protection asymmetry is why most FBM sellers default to Buy Shipping even when a label elsewhere is slightly cheaper. The math changes only when the rate gap gets big — heavy items, oversized boxes, or sellers with strong commercial rates of their own. If you do buy postage outside Amazon, the burden shifts entirely to you: valid tracking, on-time delivery evidence, and any claim fallout.
FBA vs FBM: two different labeling worlds
Amazon sellers deal with two unrelated kinds of labels, and conflating them causes real mistakes. FBM (Fulfilled by Merchant) labeling is what this whole page is about: a carrier shipping label with the buyer's address, one per order, exactly like any other marketplace. FBA labeling is a different universe — FNSKU barcode stickers on each unit so Amazon's warehouse can identify your inventory, box ID labels on each carton, and the carrier label for the inbound journey. FNSKU and box ID labels are generated only inside Seller Central; no external tool can make valid ones.
Where the two worlds touch: the outside of an FBA inbound carton carries both a carrier shipping label and Amazon's box ID label. Place them on the same face of the box where possible, flat, not over any seam — and never let the carrier label overlap the box ID barcode. A carton the fulfillment center can't scan sits in receiving limbo while your inventory shows as 'in transit' for weeks.
⚠️ Never cover an FNSKU or box ID barcode with tape carrying print, strapping, or another label. Unscannable inbound cartons are one of the most common causes of delayed FBA check-ins.
The metrics your shipping labels feed
Amazon runs FBM sellers against hard numeric thresholds, and label workflow is what moves them. Valid Tracking Rate must stay at 95% or higher — every shipment needs a real, scannable tracking number from a recognized carrier, entered before or at shipment confirmation. Late Shipment Rate must stay under 4% — measured from order to carrier acceptance scan, not to when you printed the label. Order Defect Rate must stay under 1%, and delivery-related claims are one of its main feeders.
Read those three together and the operational picture is clear: print the label fast, get a real acceptance scan the same day, and make sure the tracking number lands in the order confirmation. A printed-but-unscanned package fails the Late Shipment clock silently; a hand-typed tracking typo fails Valid Tracking Rate loudly. Sellers suspended over metrics almost always lost the acceptance-scan habit first.
FBA inbound: the Partnered Carrier bargain
For getting inventory to Amazon's warehouses, the Partnered Carrier program is usually the cheapest ground option a small seller can access: Amazon's negotiated UPS rates, offered during shipping plan creation, with labels generated by Amazon and charges billed to your seller account. For typical small-parcel inbound cartons it routinely beats anything you can buy independently.
You'd ship inbound outside the partnered program when using a carrier it doesn't cover for your route, consolidating through a freight forwarder or 3PL, or when a pallet-level LTL shipment needs arrangements Amazon's flow doesn't handle for you. In those cases you generate your own carrier label — with the fulfillment center's exact address from the shipping plan and your shipment ID as the reference — and Amazon's box ID labels still come from Seller Central regardless.
Multi-channel sellers: keeping Amazon separate but consistent
Most FBM sellers also sell somewhere Amazon isn't — a Shopify store, eBay, wholesale accounts. The discipline that keeps metrics safe is treating Amazon orders as their own queue with their own rules (Buy Shipping by default, tracking always confirmed) while keeping the physical workflow identical: same 4×6 thermal stock, same packing station, same scale. This tool covers the non-Amazon side of that operation and the edge cases — sample shipments to reviewers or wholesale buyers, warranty replacements, and any label where postage comes from an account Amazon never sees.