Why a shipping label won't scan, and how to fix it
Last updated October 28, 2026
Most unreadable shipping labels come from a short list of print and application problems. FedEx publishes a one-page printer guide that covers them, and the same causes apply to labels from any carrier. Go through the list below from top to bottom.
| Symptom | Likely cause | What to try |
|---|---|---|
| Narrow white lines across the barcode | Dirty or damaged print head (thermal) | Clean the print head with a cleaning card or pen; if lines remain, the head may need replacing |
| Faded print or small white voids | Aged or dirty ribbon, wrong heat or speed settings, low toner | Check the ribbon, heat and speed settings; replace toner; print solid black on white |
| Barcode cut off or too close to an edge | Not enough blank margin (quiet zone) on each side | FedEx's guide asks for 0.10 in or more on all sides; reprint at Actual size with no cropping |
| Label smaller than expected | Printer or viewer scaled the page | Print at Actual size and measure; USPS says labels should print approximately 4 × 6 in |
| Barcode on a seam, edge or rough surface | Placement | Put the label on the largest flat face, away from seams and edges |
| Wrinkles or lifting corners | Application | Apply with pressure and smooth out wrinkles |
| Tape or a plastic pouch over a plain-paper label | Tape or plastic can damage scanning ability, says FedEx | Per FedEx, avoid taping over labels, especially over the barcode |
| Coloured label stock | Low contrast | Use black on white; if part of the label is coloured, keep the barcode background white |
A quick procedure
- Print a test label at Actual size and measure it.
- Inspect the barcode under good light for lines, voids and light patches.
- Scan it with your own scanner and compare the number with the text printed under the barcode.
- Change one thing at a time (cleaning, darkness, stock) and re-test, so you know what fixed it.
- If a label will not scan after fixes, print a new label and, if you were charged for the bad one, request a refund under your carrier's rules. USPS says an online label cannot be altered and must be used as printed, so do not hand-edit or re-draw a label.
This guide summarizes public carrier guidance and general printing practice; it cannot tell you whether a carrier will accept a particular label. If you use Labelloom to re-flow a label PDF, test-print and test-scan it first; it keeps labels at 100% scale and warns when the margin around the printed area is small.
Sources
- FedEx, "Printer maintenance guidelines" (PDF, last update February 20, 2023 per the document): https://www.fedex.com/content/dam/fedex/us-united-states/shipping/images/printer_maintenance_guidelines.pdf (read 2026-10-28)
- USPS, "Click-N-Ship — The Basics" (FAQ): https://faq.usps.com/articles/Knowledge/Click-N-Ship-The-Basics (read 2026-10-28)
- FedEx, "How to create, print, and manage shipping labels": https://www.fedex.com/en-us/shipping/create-shipping-label.html (read 2026-10-28)
Related tool: Labelloom. Estimates and guidance only; check the source documents before relying on a figure.