A-One 80321/A4/3 × 8 = 24 per sheet/66 × 33.9 mm
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Letters and digits, up to 5. Goes in front of every ID on the sheet.
Q is free for a bare ID. H survives more damage and, with a prefix, may need a larger code — watch the QR readout.
Print the test sheet on plain paper, lay it over a label sheet and hold both to a window. Negative values move the printing up and left: if it lands 2 mm low, set Shift down to −2. Saved per stock in this browser.
Under 0.9 mm per module. It will still scan, but hold the phone closer and keep the label clean. Dropping the prefix or using error correction Q buys the module size back.
Print at 100%. Any scaling throws every label on the sheet out of register. In macOS Preview that means choosing Scale: 100% rather than Scale to Fit — both “Print Entire Image” and “Fill Entire Paper” resize the page. Elsewhere look for “Actual size”, and turn off “fit to page” or “shrink to printable area”. Set the paper to A4.
Feed each sheet once. A label sheet that goes through a laser printer twice can jam or shed adhesive.