QR codes on business cards: what to actually encode

Encode a vCard with four fields — name, one mobile, one email, one website — print it at 2.5 cm on the back of the card, and put the phone number and email in readable text as well.

That covers most people. The rest explains when it does not, and where each of those numbers comes from.

vCard or a link to your page

The only decision that really matters, and it happens before you generate anything.

A vCard is a contact file carried inside the code itself. The camera decodes it, the phone offers “Add to Contacts”, and the details land in the address book. Nothing is fetched, so it works in a lift or a basement conference room with no signal — see do QR codes work without internet.

A link sends people to a page you control, which you can change whenever you like.

	vCard	Link to a page
Needs a connection	No	Yes
Steps to save the contact	1 tap	3–4 taps, if they bother
Changeable after printing	No	Yes
Symbol density	High	Low
Breaks when	never — it is self-contained	domain lapses, page moves, host shuts down

Use a vCard when your details are stable. Most people’s are. A mobile number survives job changes; an email at your own domain survives most things.

Use a link when they are not. If you change employer every eighteen months, or the number on the card is a desk extension that gets reassigned, a link to yourdomain.com/marcus is the better call — you update one page instead of reprinting a box of cards. Cards are cheap, so a reprint is not the disaster people treat it as, but do not encode a detail you already know is temporary.

Why vCard 3.0 and not 4.0

We generate vCard 3.0 (RFC 2426, 1998) deliberately, even though 4.0 (RFC 6350) is the current standard.

4.0 is the better spec. It is also imported inconsistently. iOS and Android have handled 3.0 identically for over a decade; with 4.0 the results vary by OS version and by which app does the import, and the failures are silent — a phone number stored as a tel: URI arrives blank, or a field is dropped without a warning.

A contact card that fails to import is worthless regardless of which specification it satisfies. Compatibility beats correctness here.

Keep the card short

Every field you add makes the symbol denser, and on a surface this small that is not a minor effect.

A minimal vCard — name, one mobile, one email, one website — is about 175 characters. Here is what each addition costs, at error correction level M, printed at 2 cm:

What you encode	Approx. characters	Modules	Module size at 2 cm
Name, mobile, email, website	175	57	0.35 mm
+ company and job title	225	61	0.33 mm
+ street address	290	69	0.29 mm
+ a one-line note	380	77	0.26 mm
Two phones, address, long note	620	93	0.22 mm

The address and the note are the worst offenders and the two nobody needs. Nobody scans a card to learn a postcode. Drop both and the symbol loses roughly a third of its module count. Accented characters cost two bytes each in UTF-8, so a name like Zoë is quietly more expensive than it looks.

Error correction is the other density trap. Raising a 175-character vCard from level M to level H takes it from 57 modules to 73 — a third larger for the same content. H is for codes that get scuffed on a wall. A card that lives in a wallet does not need it. Stay on M.

The size trap

A business card is 85 × 55 mm. There is not much room, so people shrink the code, and this is where cards fail. At 0.22 mm each black square is thinner than a printed hairline, and two things break at once.

Printing. A good offset press holds 0.25 mm modules; a digital press or a quick-print shop, less reliably — ink spread on coated stock thickens the dark modules and closes the white gaps between them. Below about 0.3 mm you are relying on the printer being better than average.

Cameras. A decoder needs roughly three camera pixels per module, plus autofocus lock and a steady hand. At normal reading distance a modern phone manages 0.3 mm and struggles below that. An older phone or a scratched lens gives up sooner.

So: 0.4 mm or larger works, 0.3 mm is a coin flip, and 0.22 mm fails often enough that it is not worth the space you saved.

Working backwards, a 175-character vCard at 2.5 cm gives 0.44 mm modules. That is the recommendation, and it is why the field count matters — size and content are the same decision. More arithmetic in QR code minimum size for printing.

Where to put it on the card

The back, usually. The front belongs to the name and the logo, and a code there competes with both. The back is normally near-empty.

Away from the trim edge. Printers cut with a tolerance of 1–2 mm. A code sitting 2 mm from the edge can come back with its quiet zone shaved off on one side, and that alone stops it scanning. Leave 5 mm clear.

With its quiet zone intact. Four modules of blank margin on every side — about 1.8 mm at 0.44 mm modules. It is not decoration; the decoder uses it to find the symbol, and designers crop it constantly.

Never across a fold. A crease through the pattern kills it, and creases collect wear, so a code that scanned on day one stops after a month in a pocket.

Printing

• Matte, not gloss. Gloss lamination and spot UV reflect overhead light straight back into the camera and wipe out whole regions of the pattern. Matte costs the same.
• Dark on light. Black on white is ideal, dark navy on cream is fine. A light code on a dark background inverts the contrast and many decoders reject it outright. Tinted modules cost contrast you cannot spare at 0.44 mm.
• Test the printed proof. Not the PDF, not the screen. Scan the physical card with an iPhone, an Android phone and Google Lens under normal office lighting. It takes a minute and it is the only test that counts.

Print the details in text too

Put the mobile number and the email address on the card as readable text, alongside the code.

Not everyone scans. Some have a cracked camera, some an old phone, some are handed your card where getting a phone out is awkward, and plenty simply will not bother. A card that is only machine-readable fails for a meaningful share of the people you hand it to.

The code is a shortcut for the people who want one, not a replacement for the information.

The setup, in order

1. Generate a vCard with four fields: name, mobile, email, website.
2. Leave error correction at M.
3. Put it on the back, 5 mm clear of the trim and away from any fold.
4. Size it at 2.5 cm minimum, with a four-module quiet zone.
5. Print matte, dark on light, with the number and email in text beside it.
6. Scan the physical proof on iPhone, Android and Google Lens before ordering the full run.