How long before take off should you check in?

Most airlines recommend checking in at least 2 to 3 hours before a flight for international travel and 1 to 2 hours for domestic flights. Online check-in typically opens 24 to 48 hours before departure, allowing you to secure your boarding pass early. It's essential to verify your specific airline's policies, as check-in times can vary. Arriving early helps ensure a smooth process through security and boarding.