United Airlines Online Check-In and Your Boarding Pass

According to the airline's public information, United online check-in generally opens 24 hours before the scheduled departure time and closes shortly before takeoff: allow around 1 hour before departure on a domestic US flight, and more on an international flight, including transatlantic routes from Paris, Nice or Geneva.

At the airport, counters and baggage drop close earlier than boarding. On a long-haul flight to the United States, plan to be checked in and to have dropped your bags at least 1 hour before departure, and arrive well before that: three hours ahead remains a reasonable margin at Paris Charles de Gaulle. The boarding gate closes before the displayed departure time, and a passenger who arrives afterward may be denied access, even if already checked in.

These benchmarks vary depending on the airport, the route and codeshare arrangements: a United flight operated by Lufthansa, Brussels Airlines or Air Canada follows the rules of the airline actually operating the flight.

Three routes lead to your United boarding pass:

• The united.com website, in the check-in section, using your six-character confirmation number, ticket number or MileagePlus number, along with your last name.
• The United app, which displays your boarding pass, gate, connections and baggage tracking.
• Self-service kiosks and counters at the airport, for anyone who needs to present a document, pay for a bag or sort out a booking issue.

What travelers sometimes call "pre-check-in" corresponds, at United, to entering information into your booking ahead of time: passport, ESTA or visa, US contact address, frequent flyer number. Filling in these details before the 24-hour window opens avoids being held up when you go to check in.

The website and app are available in English, but some screens and some airline emails may appear in a different language depending on where you booked and which channel you used.

Some bookings cannot be completed online and are redirected to an agent: an unaccompanied minor, a pet in the cabin, a special assistance request, an oversized bag, a ticket bought through a travel agency with incomplete details, or a missing document check required to enter the United States.

Once check-in is confirmed, United offers a mobile boarding pass in the app, delivery by email or text message, addition to your phone's wallet, and a printed paper version. Check that it shows your name exactly as it appears on your passport, the flight number, terminal, gate and seat.

The mobile pass is not accepted everywhere: some airports, particularly at secondary stops or outside the United States, still require a paper document, printed at a counter or kiosk. If your trip has several segments, check that each leg has its own pass: a connection operated by another Star Alliance member is sometimes issued only upon arrival at the stopover.

Your seat can change after check-in, in the event of an aircraft swap or overbooking. A boarding pass marked for gate seat assignment remains valid but means you should arrive early at the boarding area.

Useful details to look for: the boarding group (United boards by numbered groups) and the TSA PreCheck marking on domestic US flights.

Check-in is only one step: baggage drop and document verification remain.

On transatlantic flights, the checked baggage allowance depends on the fare and cabin. Basic Economy fares are the most restrictive and do not always allow a cabin bag to be placed in the overhead bin depending on the route; on domestic US flights, checked baggage is generally chargeable in Economy. MileagePlus elite members and holders of certain co-branded credit cards get higher allowances. The fare paid and the destination determine the details, which appear in your booking and on the baggage page of the airline's official website.

Baggage drop takes place at Bag Drop counters after online check-in, often after printing a tag at a kiosk. Oversized items, musical instruments and sports equipment must go through a dedicated counter and should be flagged in advance.

To enter the United States, ESTA (or a visa) and a valid passport are checked at check-in, along with your US address. Missing information prevents the boarding pass from being issued until it is corrected.

In the event of a cancelled flight, delay or missed connection, United generally rebooks the passenger and reissues boarding passes in the app.

United is a founding member of Star Alliance: a ticket issued by the airline frequently includes a segment operated by a partner, in which case the operating carrier's own procedure applies, with its own opening times and its own baggage rules.

The check-in rules of the partners most often combined with United are detailed here: Air Canada for flights to Montreal and Toronto, All Nippon Airways and Asiana Airlines for Asia, Austrian Airlines via Vienna, Aegean for Greece and Air New Zealand for the South Pacific.

When check-in opens at an inconvenient hour, overnight or during another flight, travelers can turn to iBoardingPass, an independent paid service, unaffiliated with any airline, that covers more than 227 airlines. It carries out online check-in automatically as soon as the airline's window opens and sends the boarding pass by email.