Some airlines allow up to 6 hours. Most overseas flights, though, won't let you check in before 6 hours. When traveling domestically, you can typically check your bags two to three hours before your flight. If you're flying overseas, you can usually do so 3?6 hours beforehand.

In the aviation industry, there is a strict "too early" window for checking bags, primarily to prevent airport luggage rooms from becoming overcrowded. Most major airlines will not allow you to check a bag more than four hours before your scheduled departure time. This is a hard rule at many airports like London Heathrow or Orlando International, where the automated baggage systems have limited storage capacity for "early" bags. If you arrive at the terminal six hours early, you will likely be told to wait with your luggage in the public "landside" area until the four-hour window opens. However, some airlines that have massive "hub" operations (like Delta in Atlanta or Emirates in Dubai) offer "Early Bag Drop" or "Twilight Check-in" where you can drop your bags the evening before or up to 24 hours in advance, but these are exceptions rather than the norm. If you have a long layover and want to explore the city without your luggage, you should look for a "Left Luggage" service or use a third-party app like Bounce to store your bags at a nearby hotel or shop, as the airline counter will rarely assist you until your specific check-in window opens.