Quick answer
The minimum scannable size of a QR code is determined by the 10:1 rule: the printed code should be at least 10 times the width of a single module. For a typical URL QR code (Version 3-4, around 29x29 modules) printed at 0.5 mm per module, the code should be at least 5 mm square. In practice, plan for 1 cm (0.4 inches) minimum for a short URL scanned at 10-15 cm distance, and 2-3 cm (0.8-1.2 inches) for comfortable handheld scanning.
Size guidelines by use case
| Use case | Minimum size | Recommended size |
|---|---|---|
| Business card | 1.5 x 1.5 cm | 2.5 x 2.5 cm (1 inch) |
| Product packaging | 1.5 x 1.5 cm | 2 x 2 cm |
| Print ad (magazine) | 2 x 2 cm | 3 x 3 cm |
| Poster or flyer | 3 x 3 cm | 5 x 5 cm or larger |
| Billboards (read from 5m) | 40 x 40 cm | 60 x 60 cm |
| Screen / digital | 100 x 100 px | 200 x 200 px |
The 10:1 rule explained
The printing-industry rule of thumb is that a QR code must be at least 10 times the width of one module in the code. A module is one of the small black or white squares that make up the QR pattern. For a standard URL QR code (Version 3) with 29 modules across, and each module printed at 0.5 mm wide, the total code is 14.5 mm wide. To comfortably scan this from 10-15 cm, the code should be at least 14.5 x 14.5 mm, ideally larger.
A simpler way to think about it: 1 cm of code width = 10 cm of scan distance. So a 3 cm code scans comfortably at 30 cm. A 5 cm code scans at 50 cm. This is why posters and billboards need much larger codes - the scan distance is much greater.
The quiet zone (white border)
A QR code needs a quiet zone of at least 4 modules of white space on all four sides. This is the white border that helps the scanner distinguish the code from the surrounding design. If you place a QR code on a colored background or right next to other graphics, the scanner may fail. Either keep the quiet zone white, or add a white rectangle behind the code.
For a 3 cm code, the quiet zone should be at least 4 mm on each side. Including the quiet zone, the total visual footprint of a 3 cm code is about 3.8 x 3.8 cm. Plan for this when designing layouts.
Color and contrast
A QR code must have high contrast between the dark and light modules. The standard is black on white, which gives the best scannability. Other high-contrast color combinations (dark blue on white, dark green on light yellow) work in most lighting conditions. Avoid:
- Red on green (color-blindness unfriendly)
- Light colors on light backgrounds (insufficient contrast)
- Dark colors on dark backgrounds (insufficient contrast)
- Same-color-on-same-color (invisible)
- Background patterns or gradients through the code (interferes with scanning)
High error-correction for small codes
For small or hard-to-scan codes, use the highest error-correction level (H = 30%). This makes the code more resilient to:
- Print imperfections on low-quality printers
- Surface texture (fabric, textured paper, curved bottles)
- Lighting glare at certain angles
- Finger smudges or partial obscuring
- Adding a logo overlay in the center (H level is required for logo overlay)
The trade-off is that H-level codes store about 30% less data, so very long URLs may not fit. For a short URL, this is rarely a problem.
Frequently asked questions
What is the minimum size for a scannable QR code?
About 1 cm x 1 cm (0.4 inches square) for a short URL scanned at 10-15 cm distance. For business cards and packaging, use 1.5-2.5 cm. For larger items like posters and billboards, scale up - a 60 cm code reads from 5 meters away.
Why is my QR code not scanning?
The most common cause is that the code is too small for the scan distance. Use the 10:1 rule: 1 cm of code width for every 10 cm of scan distance. Other causes: insufficient contrast between code and background, missing quiet zone (white border), a logo placed without enough error correction, or the code is warped (printed on a curved surface without alignment pattern support).
What size QR code for a business card?
Aim for 2 to 2.5 cm (0.8 to 1 inch) square. This is large enough to scan reliably with most phones at the typical 10-15 cm holding distance, but small enough to leave room for other content on a standard 8.5 x 5.5 cm business card.
What is the quiet zone of a QR code?
The quiet zone is the white space required around all four sides of a QR code. The standard minimum is 4 modules (the small squares that make up the code) on every side. If your code is 2 cm square, the quiet zone should be at least 2.5 mm on each side. Without the quiet zone, scanners can fail to detect the code's edge.
How big should a QR code be on a poster?
For a poster viewed from 1-2 meters, use at least 3-5 cm. For larger distances, scale up: a poster viewed from 5 meters needs a 20-30 cm code. The rule of thumb is 1 cm of code width per 10 cm of expected scan distance. Outdoor billboards viewed from 10+ meters need codes 50-100 cm wide.
Can I make a QR code too small?
Yes. Below 1 cm square for a short URL, smartphones start failing to read the code reliably. Below 5 mm, even good scanners in good lighting will fail. The 10:1 rule (1 cm of code per 10 cm of scan distance) is the safest guideline.
Does print quality affect QR code readability?
Yes. A 300 DPI print is the minimum standard for clear QR codes. Lower DPI (like newspaper print at 150 DPI) works for larger codes but can cause issues for small ones. Use vector formats (SVG or EPS) when possible - they scale to any size without quality loss and print perfectly at any DPI.
What size QR code for product packaging?
For retail packaging, use 1.5 to 2.5 cm square. Make sure to include the 4-module quiet zone on all sides. For very small products (cosmetics, jewelry), consider whether a QR code is the right choice at all - sometimes a URL is more practical. Test the code on the actual printed material before mass production.
Generate a properly sized QR code
QRBuilt lets you set the size from 100-500 pixels in the Style tab, and exports at any resolution you need. For print, use the SVG or EPS format - they are vector formats that scale to any size without quality loss.
Create Your QR Code