QR codes connect printed material to the online world: menus, posters, business cards, packaging, event tickets, and product manuals all use them. Creating one takes seconds. Creating one that scans instantly from across a room, on a glossy poster, in dim light, takes a little more thought. This guide covers what to put in a code and how to design and test it properly.
What a QR Code Can Contain
A QR code simply stores text. Phones recognise certain text formats and offer an action, such as opening a link or joining a network:
| Purpose | What to encode |
|---|---|
| Website | https://www.example.com/menu |
mailto:hello@example.com | |
| Phone call | tel:+441234567890 |
| Text message | SMSTO:+441234567890:Hello |
| Wi-Fi network | WIFI:T:WPA;S:NetworkName;P:Password;; |
With the ToolGhost QR Code Generator, you type or paste any of these into the text box, choose the size and colours, and generate the code.
Keep the Content Short
The more characters you encode, the more modules (the small squares) the code needs, and the denser it becomes. Dense codes need to be printed larger and are harder to scan. A few tips:
- Use the shortest version of a URL that works, without tracking parameters you do not need.
- Link to a web page with details instead of encoding a long paragraph of text.
- For contact details, a link to an online profile is often simpler than a full contact card.
Size: How Big Should You Print It?
A practical minimum for close-range scanning, such as a business card, is about 2 × 2 cm (0.8 × 0.8 in). For codes scanned from further away, a common rule of thumb is that the code's width should be at least one tenth of the scanning distance:
- Scanned from 30 cm (a table or flyer): at least 3 cm wide
- Scanned from 1 metre (a counter display): at least 10 cm wide
- Scanned from 3 metres (a wall poster): at least 30 cm wide
For print, generate the largest image size available and scale it down in your design software rather than enlarging a small image, which can blur the edges.
Colour and Contrast
- Dark on light: Scanners expect dark modules on a light background. Inverted codes (light on dark) fail on some phones.
- Strong contrast: Black on white is ideal. Brand colours work if the foreground is much darker than the background, such as navy on cream.
- Avoid similar shades: Red on orange or grey on grey may look stylish but scans poorly.
- Keep the quiet zone: Leave a clear margin around the code, ideally at least four modules wide. Text or graphics too close to the edge stop scanners from finding it.
The ToolGhost generator lets you set both the foreground and background colour, so you can match your branding while keeping contrast high.
Error Correction
QR codes include built-in redundancy, so they still scan when partly damaged or dirty. There are four levels:
| Level | Approximate damage it can recover from |
|---|---|
| L | 7% |
| M | 15% |
| Q | 25% |
| H | 30% |
Higher levels make the code denser. They matter most for codes printed outdoors, on packaging that may get scuffed, or when placing a small logo over the centre.
Static vs Dynamic QR Codes
A static QR code stores the content directly. It never expires and needs no account or subscription to keep working, but it cannot be changed after printing. A dynamic code stores a short redirect link managed by a paid service, so you can change the destination and see scan statistics, but it stops working if the service or subscription ends.
The ToolGhost generator creates static codes. To keep the option of changing the destination later, point the code to a page on your own website that you control, such as yourbusiness.com/menu, and update that page as needed.
Testing Checklist Before You Print
- Scan the code with at least two different phones, ideally one iPhone and one Android.
- Test the printed proof, not just the screen version.
- Scan from the real distance and lighting where the code will be used.
- Check the destination opens correctly on mobile data, not only on your office Wi-Fi.
- Make sure the landing page is mobile friendly, since everyone arriving from a QR code is on a phone.
- Add a short call to action next to the code, such as "Scan to see today's menu", so people know why to scan it.
Safety and Privacy
- QR codes can hide malicious links. Encourage trust by printing the short web address next to the code, and check public codes for tampered stickers placed over the original.
- Only encode Wi-Fi passwords for guest networks, not your main network.
- The ToolGhost generator creates the code image using the free QR Server API (api.qrserver.com), so the text you encode is sent to that service to draw the image. Avoid encoding confidential information in any QR code.
Frequently Asked Questions
Do QR codes expire?
Static QR codes do not expire. They work as long as the content they point to, such as your website, is still available.
Do I need an account to create a QR code on ToolGhost?
No. The QR Code Generator is free and works without signing up.
Why won't my QR code scan?
The most common causes are low contrast, a code printed too small for the scanning distance, a missing quiet zone around the edges, or too much data making the code dense.
Can I put my logo in the middle?
A small logo covering the centre can work because of error correction, but always test thoroughly. Keep the logo under about 20% of the code's area.