Everything You Need to Know About QR Codes (URLs, WiFi, Contacts, Business Cards)

QR codes went from restaurant-menu novelty to daily infrastructure faster than almost any technology in recent memory. They’re on business cards, restaurant tables, event tickets, product packaging, and shop windows. But most people who use them don’t know what’s actually inside one, or that a QR code can do a lot more than open a URL. This guide fixes both.

The four things people actually put in a QR code

1. A URL

Type the URL, generate the QR, print or display. When someone scans, their camera app offers to open the link. This is 90% of QR code usage.

https://toolvaults.net

No special formatting — just the URL as text. Modern camera apps (iOS Camera, Android Google Lens, WeChat) all recognise it automatically.

2. WiFi credentials

Print this and stick it near your router. Guests scan and their phone offers “Join CoffeeHouse network?” without typing anything.

WIFI:T:WPA;S:CoffeeHouse;P:latte1234;;

The format:

• T: — the network type. Usually WPA (works for WPA/WPA2/WPA3). Use WEP for old networks or nopass for open ones.
• S: — the network name (SSID).
• P: — the password. Leave empty for open networks.
• Both semicolons at the end are required.

If your network name or password contains ;, ,, ", :, or \, escape it with a backslash: PASS\;WORD.

3. A contact card (vCard)

For business cards — someone scans, their phone offers “Add Alex Rivera to Contacts.” No hunting for your details later.

BEGIN:VCARD
VERSION:3.0
FN:Alex Rivera
ORG:ToolVaults
TITLE:Founder
TEL:+15551234567
EMAIL:alex@example.com
URL:https://toolvaults.net
END:VCARD

Only BEGIN:VCARD, VERSION:, FN: (full name), and END:VCARD are required. Everything else is optional; add what you want.

4. Plain text

Anything goes — a poem, an activation code, an inventory number. If it starts with http:// or https://, phones treat it as a URL; otherwise they show it as text with a copy button.

Error correction — the letter that matters

Every QR code has an error correction level: L, M, Q, or H. This controls how much of the QR can be damaged or covered before it stops scanning:

• L — tolerates ~7% damage. Smallest code (fewer dots). Use when the code will be pristine (screen display, freshly printed).
• M — ~15% damage. The default. Good balance for most physical printing.
• Q — ~25% damage. Use for printed materials that will get scuffed (sticker on a shipping box).
• H — ~30% damage. Densest code. Use when you overlay a logo in the middle — the QR will still scan despite the logo covering some of it.

Custom colors — the rules that matter

You can color QR codes. Some rules apply:

• Dark on light — never inverted. Scanners look for dark modules on a light background. A light-on-dark QR often fails to scan. Some newer scanners handle inverted codes, but don’t rely on it.
• Contrast is the whole game. Dark blue on white — fine. Light grey on white — bad. If you can barely see the pattern with your eye, a phone camera will struggle too.
• Solid colors, not gradients. A subtle gradient in the modules might survive; a dramatic one will break the scan.
• Keep the quiet zone. The white margin around the QR is part of the code — scanners use it to find the boundary. Don’t crop it or fill it with pattern.

Sizing for print

• Minimum size: ~2 cm (0.8″) square for a URL of typical length. Smaller than that and phones start to struggle at arm’s length.
• Business card: ~2.5-3 cm works well. Anything smaller than 2 cm is hit-or-miss on cards handed across a table.
• Poster / restaurant table: at least 5 cm (2″). Ideally more if guests scan from a seated distance.
• Billboard or storefront window: the rule is roughly “height in cm ≈ 10 × distance in metres.” A code meant to be scanned from 5 m away should be at least 50 cm on a side.

Common questions

How much data can a QR code hold?

In practice: up to about 4000 characters of text, 2900 bytes of binary, or a URL of up to ~2000 characters. The more you cram in, the denser the pattern gets — a busy QR needs to be printed larger to remain scannable.

Do QR codes expire?

Not the codes themselves. But a URL-based QR is only useful as long as the URL works — if you shut down the site or change the URL structure, the printed QR becomes a dead link. Use a permanent short-URL or a controlled redirect service if that’s a risk.

Are QR codes safe?

The code itself is inert — just a picture. The risk is what the encoded content leads to. A malicious URL can lead to a phishing page. Modern phones show you the target URL before opening it; check it before you tap.

Making one

Use our QR Code Generator — supports plain text, URLs, WiFi, and vCards, custom colors, error correction level selection, and downloads as PNG or SVG. Runs entirely in your browser — the content you encode never leaves your device, which matters for WiFi passwords and personal contact info.

If you need to URL-encode something before dropping it into a QR (e.g. a URL with special characters as a query parameter), URL Encoder will handle that first.