How to make a Wi-Fi QR code guests can scan to connect

What actually goes inside a Wi-Fi QR code

Unlike a website code, a Wi-Fi code does not encode a URL. It encodes a short structured string that phones recognise as network credentials, in the form WIFI:T:WPA;S:NetworkName;P:Password;H:false;;. T is the security type, S is the SSID, P is the password and H flags whether the network is hidden.

Because everything the phone needs is in the pattern, the code works with no internet connection, no account and no provider in the loop. That also means it is inherently static: change the Wi-Fi password and the old code stops working, so you reprint. Plan for this by choosing a password you intend to keep for a while.

The security type matters more than people expect. Most modern routers run WPA2 or WPA3, both of which are encoded as WPA. An open network with no password uses nopass, and legacy WEP has its own value. If you encode WPA on an open network, the phone will try to send a password to a network that does not want one and the join silently fails.

Making the code, step by step

Start on the router admin page or the label on the underside of the device and copy the SSID exactly as it appears, including capitalisation and spaces. A single wrong character produces a code that scans perfectly and joins nothing, which is a maddening thing to debug in a busy café.

Next, decide which network you are sharing. If your router supports a guest network — most consumer and business routers made in the last decade do — enable it and encode that one. Guest networks isolate clients from the main LAN, which keeps a stranger's laptop away from your point-of-sale terminal, network printer, security recorder and any shared drives. This is the single most important decision in the whole process.

Then generate the code, style it if you want, and test before printing. Scan with at least one iPhone and one Android handset, and specifically test with a phone that has never joined the network, since a phone that already knows the network will appear to succeed regardless.

• Copy the SSID character-for-character, including case and spaces.
• Enable and encode the guest network, not the primary LAN.
• Tick the hidden-network flag only if the SSID is genuinely not broadcast.
• Test on a phone that has never connected to the network before.
• Keep the plain-text password printed in small type as a fallback.

Where to place it and how big to print it

Wi-Fi codes are scanned at close range — someone sitting at a table, standing at a reception desk, or unpacking in a holiday rental. That puts the scan distance in the 30–50 cm band, so 3 cm square is comfortable and 2 cm is the practical minimum. There is rarely a reason to go smaller; the whole point is that it is easy.

Good placements share one property: the guest is already stationary and looking at the surface. Table tents, the inside of a menu's back cover, a card in the welcome folder, a small acrylic stand at reception, a sticker inside a hotel wardrobe door. Bad placements are anywhere a person is walking, or anywhere the code sits behind glossy glass that throws camera glare.

Print dark on light with a clear four-module quiet zone, and use error correction level M. If you are laminating or placing the code where it will get handled and scuffed — a bar top, a shared workspace — step up to Q so a scratched corner still decodes.

Troubleshooting a code that will not connect

If the camera reads the code and shows the raw WIFI: string as text instead of offering to join, the phone's OS is too old to handle the Wi-Fi payload natively. Android below version 10 and iOS below 11 both behave this way. The fallback is a dedicated scanner app, or simply the printed password.

If the phone offers to join but then fails, the cause is almost always one of three things: a mistyped SSID, the wrong security type, or a hidden network without the hidden flag set. Work through them in that order. Re-scan your printed code and read the decoded string carefully rather than trusting the form you filled in.

If it works on Android and not on iOS, check for special characters in the password. Semicolons, colons, commas and backslashes have meaning inside the Wi-Fi payload format and must be escaped; a generator that does not escape them will produce a code that truncates the password. The quickest fix is a password without punctuation.

• Raw text shown instead of a join prompt — the phone OS is too old.
• Join fails immediately — SSID typo or wrong security type.
• Works on some phones only — unescaped punctuation in the password.
• Nothing scans at all — quiet zone cropped or code printed too small.