Editorial
Guides from the bench
12 original articles, about 155 minutes of reading, written by the LabelStack editors for people who reprint labels after a jam and need the grid to hit the sticker. These are not marketplace copy-paste pages and not keyword doorways. If a measurement is wrong, tell us.
Print alignment
How to print Avery 5160 barcode labels that actually line up
Avery 5160 is a 30-up Letter sheet: three columns of 2.625″ labels, ten rows of 1″ labels, with 0.1875″ side margins and 0.5″ top and bottom. When a barcode PDF looks perfect on screen and lands a quarter inch off the sticker, the printer—not the grid—is usually at fault. This guide is the checklist we use on the bench before a production run.
14 min read · August 28, 2026
Symbology chooser
Code 128 vs UPC vs EAN vs FNSKU: which barcode should you print?
A barcode is not a decoration. Retail checkout, Amazon inbound, and a warehouse bin location each expect a different symbology. Printing the wrong one is how cartons sit in “unfulfillable” or a register beeps no-match. This chooser is the one we wish we had printed above the pack bench.
16 min read · August 28, 2026
Amazon FBA
Amazon FBA FNSKU labels: what to print and what not to mix
An ASIN is a catalog listing. A UPC is a GS1 retail GTIN. An FNSKU is Amazon’s warehouse identity for your unit in a given condition. Printing the retail UPC on an FBA inbound box is how inventory lands in the wrong bin. This guide is for sellers who reprint FNSKU sheets after a jam and need the sticker to scan at the fulfillment center.
15 min read · August 28, 2026
Validation
GS1 check digits for UPC, EAN, and ITF-14 — worked examples
The last digit of a GTIN is not decoration. It is a modulo-10 checksum. One transposed digit in a 200-row CSV will print 200 labels that a register rejects. LabelStack computes the checksum per row and tells you which spreadsheet line is wrong. This page walks the arithmetic so the red row is not a mystery.
14 min read · August 28, 2026
Print quality
Why barcodes should be SVG: quiet zone, DPI, and scanners
A barcode is a machine-readable measurement of black and white modules. If you screenshot a code, JPEG it, or let a printer scale it, the modules stop being even. Handheld scanners are unforgiving. This is the print-quality standard we hold the LabelStack PDF to.
13 min read · August 28, 2026
Operations
A bulk CSV barcode workflow that does not leak your catalog
Most reprint disasters start in a spreadsheet: the wrong column mapped as the barcode, a header treated as a SKU, a UPC with a broken check digit. A bulk generator should fail those rows before a single sticker comes out. This is the working-sheet recipe we use so a jam at 2 a.m. is a reprint, not an upload to a stranger’s server.
14 min read · August 28, 2026
Retail GTINs
Why you should not invent UPC or EAN numbers
Plenty of “free UPC generators” will happily draw bars for a 12-digit string that passes a check digit. That is a math trick, not a catalog identity. Retailers, Amazon, Walmart, and Target treat a GTIN as a licensed number. This guide is the blunt version of that distinction, written so a shop does not print 500 stickers of someone else’s code.
12 min read · August 28, 2026
Printers
Laser vs inkjet for barcode labels: toner, ink, and stock
A barcode is a contrast problem. Office printers were built for letters, not for modules that a gun will measure. Choosing laser vs inkjet, 5160 vs 8160, and real black vs “looks black” is the difference between a sheet that scans in the aisle and a sheet that only scans under your desk lamp.
12 min read · August 28, 2026
Warehouses
Warehouse bin and location barcodes that stay scannable
A bin label is not a product label. It has to survive a forklift aisle, a dusty shelf lip, and a handheld scan from three feet. The symbology is almost always Code 128 of a location you invented on purpose. This guide is the house standard we recommend when a shop outgrows writing “back left” on painter’s tape.
12 min read · August 28, 2026
Books
ISBN-13 book barcodes for small presses and self-publishers
A modern ISBN is already an EAN-13. If you own 978-0-123456-78-9, the barcode is those 13 digits with the hyphens gone. This guide is for the small press or self-publisher who needs a scannable bookland code on a sticker or a cover proof, without uploading the title list to a hosted generator.
11 min read · August 28, 2026
Paper sizes
Letter vs A4 label sheets: why the PDF must match the paper
An Avery 5160 PDF is 8.5″ × 11″. An Avery L7160 PDF is 210 × 297 mm. They are not interchangeable “close enough” pages. Printing one on the other is the most common international alignment failure we see, and it has nothing to do with barcodes.
11 min read · August 28, 2026
QA
How to test-scan barcode sheets before a production run
The cheapest barcode error is the one you catch on a single proof sheet. The expensive one is the one you find after 400 units are in a carton. This is a short protocol you can run in five minutes with a phone, and a stricter one if you own a handheld gun.
11 min read · August 28, 2026