Convert between pixels, print size, and DPI so prints stay sharp.
A QR image file has no physical size of its own — it is just a grid of pixels. DPI (dots per inch) is what maps that grid onto paper: the required pixel width equals the print width in inches multiplied by the DPI. Commercial print shops expect 300 DPI; large-format posters viewed from afar get away with 150; tiny high-detail labels may need 600.
Pixels alone do not decide whether a code scans — modules do. A module is one of the small black or white squares in the code, and the printed size of each module is what a phone camera must resolve. The rule-of-thumb minimum printable module on consumer printers is about 0.33–0.4 mm, and 0.5 mm or more is comfortably safe. A dense vCard code squeezes 57 modules into the same width a short link covers with 25, so each module prints less than half as large — that is why density matters as much as centimetres.
Screens are far more forgiving than paper: a monitor shows roughly 100–160 pixels per inch and phones zoom freely, so a small export can look sharp on screen yet blur in print. Use this calculator whenever a design goes to a printer: pick the real printed width, the printer's DPI, and the content density, and export at least the pixel width it reports — or sidestep the problem entirely by downloading a vector format such as SVG or PDF.
A 2 cm code on a card needs only 237 px at 300 DPI — but density is the trap: a typical URL prints 0.61 mm modules (sharp), while a full vCard drops to 0.35 mm (borderline). Encode a short dynamic link instead of a raw vCard and the same 2 cm scans first try.
An event poster in a mall corridor is scanned from a metre away, so print the code 8–10 cm wide. At 300 DPI a 10 cm code needs 1182 px — a 1024 px export is slightly under, so go to 2048 px and every module lands over 2.4 mm, sharp from across the hallway.
Delivery boxes and retail shelf labels often print on 600 DPI thermal printers: a 3 cm sticker needs 709 px and gives a typical URL 0.91 mm modules — plenty. Below 1.5 cm even a short link goes borderline, so keep stickers at 2 cm or more for glossy or curved packaging.
Multiply the print width in inches by the printer DPI: a 5 cm code at 300 DPI needs about 591 pixels. As a rule, a 1024 px export covers everything up to roughly 8.7 cm wide at 300 DPI, which handles business cards, stickers, and most flyers comfortably.
Pixels are the digital grid of the image file; DPI (dots per inch) says how densely those pixels are laid onto paper. The same 1024 px file prints about 8.7 cm wide at 300 DPI but 17.3 cm at 150 DPI — the file has no physical size until a DPI maps it onto the page.
A module is one of the small black or white squares that make up the code, and the scanner must resolve every single one. The practical minimum printable module on consumer printers is about 0.33–0.4 mm, with 0.5 mm or more comfortably safe. That is why a dense vCard code needs a bigger print than a short link — more modules must share the same width.
No — pixels beyond what the printer can lay down are simply discarded, and file size grows for nothing. Sharpness is capped by the physical module size, not the pixel count: a 4096 px export of a dense code printed 1 cm wide still fails, because each module lands below the printable minimum. Fix density or print size first, then match the pixels.
For professional printing, always prefer a vector format (SVG, PDF, or EPS): it scales to any size with perfectly crisp module edges and makes this whole calculation unnecessary. Use PNG when the destination requires a raster image — then this calculator tells you the minimum pixel width to export so the print stays sharp.
Screens display around 100–160 pixels per inch and browsers smooth-scale images, so a small file can look fine on a monitor. Print at 300 DPI demands roughly two to three times more pixels for the same physical width, and enlarging a small PNG smears the module edges the scanner depends on. Re-export at the required width instead of upscaling.
Dynamic QR codes let you change the destination anytime — no reprinting — and show you every scan: when, where, and on which device. Try the full QRA studio free for 14 days.