How to make a QR code that actually scans

QR codes are everywhere — restaurant menus, business cards, conference badges, the back of every package. Most look fine on screen and then fail to scan from any distance. The fix is understanding four settings and picking the right one for your context.

The four settings that matter

The QR Code Generator exposes:

1. Content. What the QR points to. A URL, a Wi-Fi network, contact info, or plain text.
2. Size. The physical or pixel size of the rendered code.
3. Error correction. L (low, 7% damage tolerance), M (medium, 15%), Q (quartile, 25%), H (high, 30%). Higher levels make the code denser.
4. Colors and margin. Foreground, background, and a "quiet zone" of white space around the edge.

These four interact. Get them right and a QR scans instantly. Get them wrong and people pull out their phones, hold them awkwardly, and walk away.

A scanning rule of thumb

The minimum scannable size depends on the scan distance:

• Up close (held in hand): 1 cm × 1 cm is enough. So 100 × 100 pixels on screen, or a 12 mm sticker in print.
• Arm's length (poster on a wall, conference badge): 3–5 cm. So 300+ pixels on screen, 30–50 mm in print.
• Across the room (3 m, like a menu QR on a wall): 10 cm minimum. Bigger is better.
• Across a parking lot (storefront window): 30+ cm. At this point you should probably also show a short URL.

Rule of thumb: minimum scannable size is roughly 1/10th of the intended scan distance.

When to add a logo

You can overlay a small logo in the middle of a QR by relying on the error correction. With error correction set to H (30%), you can obscure up to 30% of the code and still have it scan. In practice, keep the logo to ~15% of the area, centered, with a small white background behind it for contrast.

If you want to add a logo:

1. Set error correction to H when generating.
2. Download as SVG (better for editing than PNG).
3. Open in any vector editor and overlay your logo at 15% of the QR area.
4. Test it with three different scanner apps before printing 10,000 copies.

For QRs without a logo, M (medium) is fine. Higher correction levels add density (smaller modules), which is harder to scan at distance, so don't over-correct.

Three things that ruin QR scans

1. Low contrast. Black on white or dark on light is the safe combination. Light on dark works for most scanners. Color on color rarely does. If you absolutely need a color QR, test exhaustively.
2. Reflective material. Glossy paper, glass, or laminated stickers reflect bright light and confuse the scanner. Matte finish always wins.
3. Curve or fold. QR codes assume a flat surface. Wrapping one around a cylindrical product (a bottle, a coffee cup) often breaks scanning. Either flat-mount it or use multiple QRs.

Wi-Fi QRs are underrated

The single best use of a QR code is a Wi-Fi network QR taped inside the guest bathroom door. The format is:

WIFI:T:WPA;S:<SSID>;P:<password>;H:false;;

Generate it, print it, laminate it. Every guest with a smartphone connects in three seconds and you never read out a 24-character WPA2 password again.