What is a QR code?
A QR code (short for Quick Response code) is a two-dimensional barcode made of black and white squares that stores information such as a website address, text, contact details or Wi-Fi credentials. Point a smartphone camera at it and the phone reads the pattern in a fraction of a second and offers to open the link or take an action.
Unlike a traditional barcode, which stores a short number in one direction, a QR code stores data both horizontally and vertically. That lets it hold far more information in a small space and still be read from any angle — even when part of it is dirty or damaged.
A short history
The QR code was invented in 1994 by Masahiro Hara and his team at Denso Wave, a Toyota group company in Japan, to track automotive parts on the production line faster than barcodes allowed. Denso Wave chose not to enforce its patent, making the format free for anyone to use, and it became an international standard (ISO/IEC 18004) in 2000. QR codes went mainstream once smartphone cameras began reading them natively, and adoption surged during the COVID-19 pandemic as businesses moved to contactless menus, check-ins and payments.
How do QR codes work?
A QR code is a grid of small squares called modules. Each dark or light module represents a bit of data. Special fixed patterns help a camera locate the code, straighten it and read it reliably:
Anatomy of a QR code
- 1Finder patterns — Three large squares that let a camera find the code and work out its angle.
- 2Alignment pattern — Helps correct distortion when the code is curved or photographed at an angle.
- 3Timing pattern — Alternating modules that tell the scanner how big each module is.
- 4Data & error correction — The black and white modules that store your content plus backup data.
- 5Quiet zone — The empty margin around the code. Without it, scanners struggle to separate the code from its surroundings.
Versions and capacity
QR codes come in 40 sizes, called versions. Version 1 is 21 × 21 modules, and each version adds 4 modules per side, up to version 40 at 177 × 177. The generator automatically picks the smallest version that fits your content. The maximum capacity of a version 40 code is:
| Data type | Maximum characters |
|---|---|
| Numeric (0–9) | 7,089 |
| Alphanumeric (A–Z, 0–9, some symbols) | 4,296 |
| Binary / bytes (e.g. URLs, UTF-8 text) | 2,953 |
| Kanji / Kana | 1,817 |
Error correction
QR codes use Reed–Solomon error correction, which stores backup data so a code still scans when part of it is scratched, faded or covered. There are four levels — choose a higher one for codes that will be outdoors, on packaging or handled often:
| Level | Recovers up to | Best for |
|---|---|---|
| L — Low | ~7% damage | Clean digital screens; smallest possible code |
| M — Medium | ~15% damage | Most print and everyday uses (default) |
| Q — Quartile | ~25% damage | Packaging, labels and industrial settings |
| H — High | ~30% damage | Harsh environments or codes likely to be partly covered |
Higher error correction adds more modules, so the code becomes denser for the same content.
Types of QR codes
Static vs. dynamic QR codes
Every QR code is either static or dynamic. A static code — the kind this free generator creates — stores your content directly in the pattern. It never expires and works without any service, but it can’t be edited or tracked once printed.
A dynamic QR code stores a short link instead. When scanned, the short link redirects to your real destination, which you can change at any time. Because each scan passes through the redirect, dynamic codes also provide analytics such as scan counts, locations and devices. Compare static and dynamic codes or see what dynamic codes can do.
QR codes by content
The content you encode decides what happens when someone scans the code:
| Type | What happens when scanned | Example use |
|---|---|---|
| Website (URL) | Opens a web page in the browser | Menus, landing pages, PDFs, videos, social profiles |
| Text | Displays a message on screen | Serial numbers, instructions, short notes |
| Opens a new email with address, subject and body filled in | Support requests, feedback, RSVPs | |
| Phone | Starts a call to the number | Service vehicles, flyers, emergency contacts |
| SMS | Opens a text message with the number and message ready | Opt-ins, voting, appointment confirmation |
| Wi-Fi | Joins the wireless network automatically | Cafés, hotels, offices, home guests |
| vCard | Saves a contact to the address book | Business cards, name badges |
| Payment | Opens a payment app with the payee pre-filled | Shops, street vendors, invoices |
Popular uses for QR codes
QR codes connect the physical world to digital content. Some of the most common ways businesses and individuals use them:
- Restaurant menusContactless menus, ordering and table-side payments, plus links to reviews.
- Product packagingInstructions, ingredients, warranty registration, authenticity checks and recipes.
- Business cardsShare your website, portfolio, LinkedIn profile or contact details with one scan.
- Guest Wi-FiLet visitors join your network instantly — no spelling out passwords.
- PaymentsAccept payments via apps like UPI, PayPal or bank transfer links at the counter.
- Events & ticketsRegistration, check-in, agendas, feedback forms and digital tickets.
- Print & outdoor adsTurn posters, flyers, magazines and billboards into measurable campaigns.
- Real estateLink yard signs and brochures to listings, virtual tours and booking pages.
- EducationShare course material, assignments, videos and attendance forms in class.
- HealthcarePatient information, appointment booking and medication instructions.
- Inventory & logisticsTrack parts, assets and shipments — the job QR codes were invented for.
- Museums & tourismAudio guides, exhibit details and translated information for visitors.
QR code design & printing best practices
A QR code only works if people can scan it. Follow these guidelines before you print:
- Keep strong contrast. Use a dark foreground on a light background. Brand colors are fine as long as the code stays clearly darker than its background — avoid light-on-dark codes.
- Leave a quiet zone. Keep an empty margin of at least 4 modules around the code, and don’t crowd it with text or graphics.
- Size it for the distance. Make the code roughly one-tenth of the scanning distance, and never smaller than 2 × 2 cm (0.8 in).
- Keep content short. Shorter URLs create simpler codes that scan faster and print smaller. Dynamic QR codes always use a short link.
- Use SVG for print. Vector files stay sharp at any size; PNGs can blur when enlarged.
- Add a call to action. “Scan to view the menu” or “Scan for 10% off” tells people why they should scan — and increases scans.
- Mind the surface. Avoid glossy reflections, tight curves and folds, and choose higher error correction for outdoor or high-wear placements.
- Always test. Scan the final printed proof with several phones, in the lighting where it will be used, before you print thousands.
| Placement | Typical scan distance | Recommended minimum size |
|---|---|---|
| Business card, label | 10–20 cm | 2 × 2 cm (0.8 in) |
| Table tent, flyer, menu | 20–40 cm | 3–4 cm (1.2–1.6 in) |
| Poster, window sign | 1–2 m | 10–20 cm (4–8 in) |
| Banner, trade-show stand | 3–5 m | 30–50 cm (12–20 in) |
How to scan a QR code
iPhone & iPad
Open the Camera app and point it at the code. Tap the yellow link that appears. You can also add “Code Scanner” to Control Center.
Android
Open the Camera app or Google Lens and point it at the code, then tap the link. On some phones, enable QR scanning in camera settings.
From a screenshot
Open the image in Google Lens or the Photos app (iOS: long-press the code) to read QR codes saved on your phone.
On a computer
Upload or drag the image into Google Lens in your browser, or use your phone to scan the code on screen.
Are QR codes safe?
A QR code itself can’t harm your phone — it only contains text. The risk is where it leads. Criminals sometimes stick fake codes over real ones to send people to phishing pages, a scam known as “quishing”.
When scanning
- Check the link preview before opening it, and look for misspelled domains.
- Be wary of stickers placed over existing codes — especially on parking meters, EV chargers and posters.
- Never enter passwords or payment details on a page you reached from an unexpected QR code.
When publishing
- Link only to secure HTTPS pages on domains you control.
- Print your brand name and website next to the code so people know it’s genuine.
- Check your printed codes regularly for tampering.