You can check in for a United Airlines flight as early as 24 hours before your scheduled departure using the United Airlines website, mobile app, or airport kiosks. Online check-in is available for both domestic and international flights and allows you to choose your seat, add baggage, and receive a digital boarding pass. For domestic flights, you must complete check-in at least 45 minutes before departure, and for international flights, check-in must be completed at least 60 minutes prior to departure. United recently updated its check-in policy to ensure passengers arrive on time and avoid last-minute delays. The boarding process begins around 30 to 40 minutes before the flight, and gates typically close 15 minutes before domestic flights and 30 minutes before international flights. If you prefer airport check-in, ticket counters usually open 3 to 4 hours before flight time and close according to the same deadlines. Self-service kiosks are available at most major airports and usually operate from 3 hours before the flight until about 30–60 minutes before departure depending on the destination. Curbside check-in is also available at select U.S. airports and typically opens 4 hours before takeoff, closing 40 to 45 minutes before departure. If you have checked bags, make sure you allow enough time for baggage drop and security screening. United recommends arriving at the airport at least 2 hours before a domestic flight and 3 hours before an international flight to ensure a smooth experience. Online check-in is ideal for travelers with only carry-on luggage who want to avoid lines and save time. However, certain passengers—such as those traveling with pets, unaccompanied minors, or those needing special assistance—must check in at the airport counter. Many travelers find that checking in online exactly 24 hours before their flight gives them better access to preferred seating or upgrades. It’s also a great way to confirm your itinerary and upload any required travel documents for international trips. United’s system is user-friendly and works well across devices, helping streamline the travel process from start to finish. In summary, United Airlines allows passengers to check in 24 hours in advance, with final check-in deadlines of 45 minutes for domestic and 60 minutes for international flights. Whether you choose to check in online or at the airport, understanding these time frames will help you avoid delays, secure your seat, and enjoy a hassle-free travel experience. Being prepared and checking in early ensures that you meet all airline requirements and arrive at your gate ready for boarding without stress.