Yes, you can almost always add extra bags at the airport, but it is rarely the most cost-effective option. Most airlines allow you to pay for additional checked luggage at the self-service kiosks or the check-in counter on the day of departure. However, "at-airport" fees are typically $10 to $25 higher per bag than the rates offered online or via the airline's mobile app. Furthermore, some ultra-low-cost carriers (like Spirit or Ryanair) charge significantly more—sometimes double—if you wait until the gate to declare a bag. If your extra bag exceeds standard weight limits (usually 50 lbs or 23 kg for economy), you will be hit with "overweight" fees in addition to the "extra bag" fee, which can quickly total over $100–$200 per piece. To save money, it is highly recommended to "Manage Booking" on the airline's website at least 24 hours before your flight to prepay for any luggage you know you will be bringing.