For international travel in 2026, online check-in typically opens 24 to 48 hours before departure, depending on the airline. However, checking in at the airport is a different story; most carriers recommend arriving at the airport at least 3 hours prior to an international flight. This is because international travel requires manual document verification (passports, visas, and health records) that cannot always be completed digitally. The "hard deadline" for checking in at the airport counter is usually 60 to 75 minutes before takeoff; if you arrive after this window, you may be denied boarding. For certain high-security routes or busy hubs like London Heathrow or Dubai, it is safer to aim for the 4-hour mark. Even if you have checked in online and have no bags to drop, you must still visit the "Document Check" or "Baggage Drop" counter to have your physical travel documents verified by an agent before proceeding to security, as digital boarding passes for international flights are often not finalized until this physical verification is complete.