In 2026, carry-on weight enforcement is becoming significantly stricter as airlines move toward a universal 22" x 14" x 9" size standard. While major U.S. carriers like Delta, United, and Southwest often don't have a strict weight limit for domestic flights (provided you can lift the bag), budget and international airlines are very different. Carriers like Frontier (35 lbs), KLM (26 lbs), and Lufthansa (17 lbs) have low, hard caps that are frequently checked with scales at the gate. As overhead bin space becomes more contested, gate agents are increasingly using their discretion to "force-check" bags that look heavy or exceed dimensions. Even if your bag fits the size, if it's over the airline's specific weight limit, you could be charged a gate-check fee of $50 to $100. To avoid surprises in 2026, always check the "Weight" section of your specific airline's baggage policy, as these numbers vary wildly between carriers.