The short answer: a printed boarding pass carries a PDF417 barcode holding the IATA BCBP (Bar-Coded Boarding Pass) data. A mobile boarding pass shown on your phone uses a 2D matrix code instead — most commonly Aztec, sometimes QR or Data Matrix — because a square code fits a screen better than a wide strip.
The IATA BCBP standard
Aviation cannot have every airline using a different code — a passenger connecting between carriers has to scan at any gate, any airport. So IATA (the International Air Transport Association) defined the Bar-Coded Boarding Pass standard, which fixes both the data layout and the symbologies allowed. Every compliant pass encodes the same fields in the same order, so any BCBP-aware reader worldwide can decode it.
Printed PDF417 vs mobile matrix codes
BCBP comes in two physical flavours:
- Printed pass → PDF417
- A wide, stacked 2D barcode. Its elongated shape sits naturally on the tear-off strip, and airport laser-and-imager hardware has supported it for decades. This is the classic "boarding pass barcode".
- Mobile pass → Aztec / QR / Data Matrix
- On a phone, a square matrix code is easier to display and scan than a long strip, so mobile BCBP allows Aztec, Data Matrix or QR. Aztec is especially common because it needs no surrounding margin.
If you want the deeper comparison of these symbologies, see QR vs PDF417 vs Aztec vs Data Matrix.
What the barcode contains
The BCBP payload is a compact string of fields, not a secret. Decoding one reveals roughly:
- Passenger name
- Booking reference / PNR (the six-character record locator)
- Flight number and operating carrier
- Origin and destination airport codes
- Date of flight and Julian date
- Seat number and boarding sequence number
- Cabin / fare class and, where present, a security signature
Notably, it does not contain payment details or a password — but it does contain enough to look up your booking, which is the basis of the privacy note below.
Signatures and security
BCBP supports a digital signature over the data. When present, a gate reader can verify the pass is genuine and unaltered without contacting a server — useful at remote gates and during outages. As with every ticket, though, the real protection is the airline's departure-control system marking each boarding pass as used, so the same sequence number cannot board twice. The barcode is the lookup key; the system enforces the rules. (See ticket security.)
Getting it to scan
- Mobile: brightness to maximum, auto-brightness off, code shown whole with a little margin. Add the pass to your phone's wallet so it works offline and surfaces quickly.
- Printed: plain paper, black on white, do not fold across the PDF417. A creased or faded thermal print is the usual reason a printed pass fails.
If it reads but is declined, the issue is in the airline's system — see why won't my ticket scan.
A privacy note on photos of boarding passes
Because the barcode encodes your name and booking reference in the clear, posting a photo of your boarding pass online can expose your booking. Anyone who decodes the code may be able to access your reservation on the airline's site. Don't share images of boarding passes, and bin printed ones rather than leaving them on the seat.