QR code formats and printing

Size to the scanning distance rather than one fixed number: a good rule of thumb is roughly a tenth of the distance a viewer will stand from it, with about 2 cm as the practical floor even up close on a card. A poster read from three meters away needs a code around 30 cm across to scan reliably on the first try.

SVG for anything going to a print vendor or design software, since its vector paths stay sharp at any size from a card to a billboard. PNG works fine for on-screen use or a fixed-size upload where the display size never changes. Choosing SVG whenever a print shop is involved avoids blurry, pixelated output later.

Dark modules on a light background give the most reliable contrast, and a full black-on-white pairing scans best of all. Lighter or closer-toned color pairs can still work but need enough contrast to stay readable by a camera; MakeQR checks every combination and flags one that's too faint before it goes to download.

Yes. A PNG download keeps transparency in its alpha channel, and an SVG has no background at all unless a solid color is added underneath. This lets a code sit directly on packaging, apparel or colored artwork instead of showing a white square around it. The dark modules still need enough contrast against whatever surface they land on.

A logo covers only the center of the pattern, and error correction rises automatically to its highest level once one is added, so the surrounding modules can still be read even with that section blocked. Print quality otherwise depends on the same factors as any code: resolution, size and contrast. A logo does not raise the minimum print size on its own.

Size mismatched to reading distance is the most frequent cause: a code sized for a business card doesn't work on a billboard read from across a parking lot. Low contrast, a low-resolution PNG stretched past its native size, and a busy background behind the code are the next most common failures, all avoidable with an SVG file and a quick scan test first.