Flying with Frontier? Understanding the 3-1-1 Rule on Frontier can help you breeze through airport security. Under the TSA's 3-1-1 rule, liquids, gels, and aerosols in your carry-on must be in containers of 3.4 ounces (100 ml) or less, all fitting inside one clear, quart-sized bag, with one bag allowed per passenger. Following these guidelines helps prevent delays and keeps your screening process smooth. If you're carrying larger liquid items, pack them in your checked baggage. Knowing the 3-1-1 Rule on Frontier before your trip makes travel easier and stress-free.