The 6 print rules that cover 90% of QR failures.

After three months of running 8 dynamic QRs at Maple Diner, I've learned what makes a QR scan reliably and what doesn't. Most people don't realize there's a checklist. They just print and hope.

These are the six rules I follow every time I send something to the printer. If you skip any of them, the QR will probably still work — but probably isn't good enough when 43% of your customers scan it.

Rule 1: Size

The minimum scan size is 1 inch (25mm) at arm's length. For storefront windows or distance scanning, scale up:

The math: a QR needs to be at least 10× larger than the scanner's required minimum module size, and modern phones can resolve roughly 1mm per module at 1 ft. A 1-inch QR has about 25 modules across, which gives you a comfortable margin.

A 0.5-inch QR? It scans about 60% of the time on a clean print, 30% with any wear or shadow. Don't.

Rule 2: Quiet zone

The quiet zone is the empty white border around the QR. Spec says 4 modules wide on all four sides. In practice, most printers default to 1-2 modules of quiet zone, which is the single biggest reason QRs fail to scan.

If you're designing the menu yourself, ensure the QR has a clear, unobstructed border. Don't tuck it next to text. Don't let a logo or graphic intrude into the quiet zone. The phone scanner needs that empty space to find the corner finder patterns.

Left: 4-module quiet zone, scans every time. Right: no quiet zone, scans about 40% of the time.

Rule 3: Error correction

Error correction is how much damage a QR can withstand and still scan. There are four levels:

• L (low): 7% recovery
• M (medium): 15% recovery
• Q (high): 25% recovery — use this for print
• H (highest): 30% recovery — use if there's a logo overlay

The default in most QR generators is M, but for printed materials I always bump to Q. The 1% increase in QR complexity is worth it for the print-resilience boost. If you're putting a logo in the center of the QR, use H — the logo essentially "damages" 15-25% of the modules, and you need the extra correction headroom.

QRBliss exports default to Q for printed PDFs, which is the right call.

Rule 4: Contrast

The QR modules (the dark squares) need to be sufficiently darker than the background to be readable by a phone camera. The contrast ratio standard for scannability is 3:1, but I aim for 4.5:1 because that also passes WCAG accessibility standards.

Practical rules:

• Dark on white: works always
• Black on dark cream: works
• Color on white: works if the color is dark enough (use the oklch() function in CSS to verify L < 50%)
• Color on color: rarely works
• Inverted (light on dark): technically supported but breaks ~40% of older Android phones

The maple-red on cream we use at the diner has a contrast ratio of 7.2:1. Way more than enough.

Rule 5: Color profile

This one is sneaky and only matters for offset printing (which most professional restaurant menus use).

CMYK printing reproduces color differently than RGB. A pure black QR module rendered in CMYK might come out as a slight gray-brown if the RGB-to-CMYK conversion isn't done correctly. This kills contrast.

The fix:

1. Export your QR as a vector PDF (not a rasterized PNG)
2. Convert to CMYK with the destination press profile
3. Pure black modules: use 100K (100% black ink only), not 4-color black
4. Send the PDF to the printer with bleed marks at 3mm

QRBliss's PDF export does steps 1-3 automatically. Just send the result to your printer.

Rule 6: Curved surfaces

If you're printing on a coffee cup, water bottle, or other cylindrical object, the QR will bend during scanning. Phone cameras can correct for some bending, but not unlimited. Rules:

• Up to 15° curvature: works fine, no special handling
• 15-30° curvature: increase QR size by 25% to maintain readability
• Over 30° curvature: doesn't work reliably, consider a flat sticker or label

Test on real customers, not just at your desk. Holding the cup at exactly the right angle in your office is not the same as a customer trying to scan in low restaurant lighting while holding a fork.

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The checklist

Before sending to print:

• Size at least 1 inch (or scaled appropriately for distance)
• 4 modules of quiet zone on all four sides
• Error correction at Q (or H with logo overlay)
• Contrast ratio ≥ 4.5:1
• CMYK color profile, modules in 100K
• If curved surface, sized up by 25%

If you can check all six, your QR will scan reliably for the next several years. If you can't check one, fix that one before printing.

I keep this checklist taped to my desk now. It saves me a phone call to the printer about every six weeks.