Good morning,
2 years selling same private label product, using same barcode thermo paper and thermo printer. Zero changes but somehow in July I started to get random “un scannable” barcodes.
They are now saying that out of 100 units 15 of them wont scan. Twice I have asked to send me a photo of one of those labels and they did. I tried scanning it myself using an iphone app and it scanned and gave me my sku so im so no understanding whats going on. Im selling 60-90 units per day.
Frustrating.
May I know which thermal printer are you using?
You need to use a barcode scanner, not an iPhone app, as the phone uses photographic technology, not what warehouse scanners use.
Also, be careful that there is sufficient light margin at both ends of the barcodes.
This is a surprisingly common issue, and it usually isn’t your printer or your barcode quality at all, it’s Amazon’s inbound scanning equipment or handling process. What you’re describing fits exactly what happens when FC scanners struggle with thermal labels that are slightly faded, wrinkled, overexposed to heat, or applied on curved surfaces, even though they still scan perfectly with a phone. Amazon’s scanners use industrial readers calibrated differently from consumer apps, and they can reject labels that look totally fine to us. The fact that the photo they sent scans on your phone actually strengthens the case that the issue is on their end, not yours.
July is also when a lot of FCs switch to higher-speed sortation lines, and labels get rubbed, smudged, or partially damaged during conveyor handling. A surprisingly small mark, abrasion, or reflection can cause Amazon’s scanners to fail even though the code remains readable in a low-speed manual context.
A few things that often fix the issue for sellers:
• Slow your thermal printer down or increase darkness to produce heavier, higher-contrast barcodes.
• Make sure barcodes are printed at least 300 dpi (some printers drift over time and need recalibration).
• Avoid printing too close to the label edge — Amazon scanners hate that.
• Switch to gloss or polypropylene labels instead of cheap thermal paper if humidity or heat is a factor.
• Make sure the barcode is at least 1.5 inches wide with enough quiet zone around it.
• Add a clear protective label on top if labels rub against each other during packing.
Many sellers also report that the problem comes and goes depending on which FC receives the shipment, which is another sign it’s a scanning environment issue rather than your labels. If the percentage is increasing, it’s worth opening a case and politely asking Amazon to log it as an FC-handling issue, because you have proof the label is scannable. But operationally, upgrading label quality or print settings is usually what finally resolves it.