Typically, you can check a bag several hours before your flight, but the exact window depends on the airline and airport. Most domestic trips allow bag drop roughly 45 minutes to 4 hours before departure, with many airlines setting a practical window of 2–4 hours for international travel. Some carriers and airports explicitly restrict check-in if you arrive too early, while others offer earlier bag drop options for premium or convenient service. Key points to know

• Domestic flights: bag drop usually opens a few hours before departure, and you’ll commonly need to be checked in at least 30–60 minutes before departure.
• International flights: expect tighter security and customs processing, so bag drop/check-in typically needs to occur at least 3 hours before departure.
• Specific airline policies vary: a few carriers allow bag drop as early as 4–6 hours before departure, while others may cap early check-in at 3–4 hours or a fixed window around the flight time.
• Airport rules can also affect timing: some airports enforce earlier or later windows for bag drop depending on terminal operations and staffing.

Practical tips

• Check your airline’s official baggage policies and the airport’s check-in hours for your specific flight to confirm the exact time you can drop or check bags.
• Arrive at the airport with ample time to spare: for domestic travel, plan to be at the airport 2 hours before departure; for international travel, 2–3 hours is a safer target, accounting for bag drop, security, and immigration/customs.
• If you’re traveling with a lot of luggage or unusual items, verify any size/weight limits and the number of bags allowed to avoid delays at the counter.

If you’d like, share your airline and route (domestic vs international), and I can give a more precise window based on that airline’s published rules.