Every flight booking has a six character code attached to it. That code is called a PNR, short for Passenger Name Record. It is the single most important identifier in your trip, the thread that ties a reservation, a ticket, a boarding pass, and any changes back to the same booking. Here is how it actually works.

What the PNR contains

A PNR is a record stored in an airline or global distribution system. Inside it you will find.

  • Passenger name and contact details.
  • Itinerary details, flight numbers, dates, times.
  • Ticket status and fare basis.
  • Seat selections.
  • Baggage information.
  • Special service requests, like meals and wheelchair assistance.
  • Frequent flyer numbers.
  • Form of payment reference.

The visible PNR code is just the pointer. Everything above is stored behind that code on the airline's servers.

Why six characters

Six alphanumeric characters give roughly 2.1 billion combinations, more than enough for an airline's needs. The constraint came from the 1970s when the original systems were built around fixed width screens and limited memory. It stayed because it works.

Letters I and O are usually excluded to avoid confusion with the digits 1 and 0. Some airlines also avoid 0 and 1 entirely.

Who creates a PNR

PNRs are created in three places.

  • Airline booking system. Directly on the airline website or app.
  • Travel agency through a GDS. Amadeus, Sabre, and Travelport are the main global distribution systems that travel agencies use.
  • Online travel agencies. Expedia, Booking.com, and similar services connect to GDSs and create their own PNRs alongside the airline's.

Airline PNR and agency PNR

If you book through an agency, you often see two PNR codes. One is the agency's record locator in the GDS. The other is the airline's record locator. Both point to the same flight but are stored in different systems. Most of the time they are identical characters, but not always.

A sample itinerary from the Print A Trip builder shows both, labelled "Reservation Code" and "Airline Reservation Code," because real GDS style documents almost always display both.

What the PNR is used for

  • Web check in, you enter the PNR and your last name.
  • Mobile app pulling up your booking.
  • Gate agent retrieving your record if your boarding pass does not scan.
  • Calling customer service about your trip.
  • Embassy or visa office verifying that a booking exists on the airline system.

See a sample PNR on a novelty itinerary

The builder generates an Amadeus style record locator for every sample document.

Open the builder

PNR privacy

Your PNR is moderately sensitive. Combined with your last name it is enough for someone to view and sometimes modify your booking on the airline website. Do not share your PNR publicly or post a photo of your boarding pass where the PNR is visible.

Many airlines have tightened this over the years. Most now require a second factor, a birth date or email, before letting anyone change a reservation. Some still operate on name plus PNR alone.

How long a PNR lives

A completed PNR typically stays in airline systems for three to four years after the last flight, then archives. GDS providers retain PNRs longer, usually seven to ten years, subject to local privacy laws. This is why old bookings can sometimes be pulled up long after the trip.

What makes a PNR invalid

  • The ticket was cancelled and refunded.
  • The hold expired before payment was received.
  • The flight date has passed and the record has archived.
  • The PNR was reissued onto a new ticket and the original was voided.

An invalid PNR will not pull up a booking, even if you have the exact six characters. Cancelled or expired reservations are one of the most common reasons passengers discover their ticket does not check in.

For the physical document that carries the PNR on it, read how real boarding passes are designed. For how the three letter codes alongside the PNR are structured, see IATA three letter airport codes explained.