Thermal receipt printers (58mm and 80mm rolls) are everywhere in retail and food service, and they're a very different printing environment than a laser or inkjet printer — QR codes that look perfect on screen can turn into a blurry, unscannable mess if you don't account for it.
Why thermal printing is different
Thermal printers use heat to darken paper rather than depositing ink, which means edges are naturally a bit softer and resolution is lower than a standard office printer. Fine detail that's crisp in a PDF can blur slightly when printed this way.
Sizing for 58mm vs 80mm rolls
- 58mm receipts — keep the QR code no larger than about 25-30mm wide to leave margin on both sides
- 80mm receipts — you have more room; 30-40mm wide gives a comfortable scan target
Use a higher error-correction level
Thermal printing benefits from a higher error-correction setting than digital-only use, since it compensates for the slight blur and any minor print-head wear over time. If your generator offers a choice, pick a higher correction level for anything printed thermally.
Keep it simple — skip fine custom colors
Thermal printers are single-color (usually black on white or a tinted paper) — custom colored QR codes won't render correctly. Stick to standard black-on-white for anything headed to a thermal printer.
Test on your actual printer
Print a single test receipt and scan it with two or three phones before running a full batch. Print head wear varies printer to printer, and what scans perfectly on one device may not on an older one.