No, a 25-inch suitcase cannot be a carry-on for any major domestic or international airline in 2026. The universal standard for carry-on luggage is 22 x 14 x 9 inches (including wheels and handles). A 25-inch bag is considered "Medium Checked" luggage and will be rejected at the boarding gate or security checkpoint. Even Southwest Airlines, which has the most generous carry-on policy in the U.S., limits bags to 24 x 16 x 10 inches, meaning a 25-inch bag is still too large. Attempting to bring a bag this size on board will likely result in a "Gate Check" fee, which can be as high as $60 to $100 on budget carriers like Spirit or Ryanair. For 2026 travelers, it is vital to measure from the very bottom of the wheels to the top of the retracted handle, as gate agents are increasingly strict with "sizing bins" to ensure bins can close on modern, high-capacity aircraft.