QR Code Guide

From generating a code to getting it printed and reliably scanned in the field — five topics that come up constantly in real projects.

01How QR codes actually work

A QR code is a two-dimensional barcode that turns a string of text into a black-and-white grid. If you enter a link, the link string itself is encoded into the grid; if you enter plain text, that text is encoded as-is. A scanner (your phone camera) locates the three large squares in the corners — the finder patterns — to work out position and orientation, then reads the grid back into the original string. The important part: a QR code is not connected to any server. The information lives inside the image itself, so a code never expires and keeps working even if the generator that made it disappears. Longer content produces a denser grid; the density steps are called versions (1–40). Higher versions hold more data, but at the same printed size each module gets smaller and harder to scan. Keeping your content short is the single best thing you can do for scan reliability.

02Choosing an error correction level

Every QR code carries redundant data so it can survive being partially covered or damaged. That recovery capacity is the error correction level: L (7%), M (15%), Q (25%) or H (30%). Raising the level makes the code more damage-resistant but also denser for the same content. Choose by environment: a code shown on a screen will never get scratched, so M is plenty — and if your content is long and capacity is tight, dropping to L is fine. For outdoor banners and stickers exposed to weather and grime, use Q or higher. H exists mainly for styled codes that deliberately cover part of the pattern with a logo. In short: M by default, Q for harsh environments, H for logo overlays, L for maximum capacity.

03Why SVG for print

Bitmap formats like PNG are grids of pixels, so edges blur into staircases when enlarged. That is harmless on screen, but stretching a small PNG onto a large banner softens the module edges — a common cause of scan failures. SVG describes shapes as mathematical coordinates instead, so the edges stay razor-sharp at any size, from a business card to a building wrap. Print shops can drop an SVG straight into Illustrator artwork and recolor or rescale it without quality loss, which is why handing over SVG is the safest choice for anything that gets printed — and why SVG is this site's primary download. For web pages and documents, PNG is convenient; just pick a resolution comfortably larger than the displayed size (1024px or more) so downscaling keeps it crisp.

04Business cards, banners, table tents

On business cards, place the QR at least 15mm wide on the back — below that, older phones struggle. Banners usually hang above eye level, so check at design time that the code sits where people can point a phone without stretching (roughly 1.2–1.8m from the ground) and print it at least 10cm wide. For restaurant and café table tents linking to menus or ordering pages, glossy lamination is the usual culprit when scanning fails — specify a matte finish. Three rules apply everywhere. First, keep the quiet zone: the blank margin around the code (this tool's default of 4 modules) is part of the spec, not decoration. Second, keep strong contrast between a dark code and a light background. Third, always print a real-size proof and test-scan it with several phone models before the full print run.

05When a QR code won't scan

Work through this checklist in order. 1) Size — the code should be at least one tenth of the scanning distance; a code scanned from one meter away needs to be at least 10cm wide. 2) Quiet zone — text or graphics butted up against the code confuse the scanner; keep at least four modules of clear space on all sides. 3) Contrast — dark code on a light background is the rule. Inverted or low-contrast color pairs prevent the scanner from finding the pattern. 4) Reflection — gloss coating, glass, or a bad lighting angle puts a highlight right where the camera needs detail; switch to matte or move the code. 5) Damage — scratches and dirt beyond the error correction budget are unrecoverable; if wear is expected, generate at Q or higher from the start. 6) Content length — very long URLs make dense grids that scan poorly at small sizes. Shorten the address and regenerate; the same printed size will scan far more reliably.