For domestic flights, you should be at the airport for a minimum of 45 minutes before your flight, although it's much safer to be there 90 minutes to two hours before departure.

For most airlines, the standard window to begin checking in for a flight opens exactly 24 hours before your scheduled departure time. Checking in as soon as this window opens is highly recommended, as it often allows you to secure better seat assignments (if they weren't pre-selected) and ensures you are high on the list for potential upgrades or standby priority. If you are checking in physically at the airport, the "cut-off" times are much stricter: for domestic flights, you should typically check in at least 90 minutes to 2 hours before departure, especially if you have luggage to drop off. For international flights, most experts and airlines recommend checking in at the airport at least 3 hours in advance to account for document verification, longer security lines, and immigration procedures. Most airlines close their check-in counters 45 to 60 minutes before takeoff, and failing to check in before this deadline can result in being denied boarding. Using a mobile app for check-in is the most efficient method, allowing you to skip the initial lines at the terminal and go straight to bag drop or security with a digital boarding pass.