For years, the carry-on argument had a fixed address. It happened at the gate, in the minute before boarding, with a metal frame and a gate agent who could say yes or no. That address is changing. Airline carry-on enforcement is moving off the jet bridge toward the lobby, the check-in counter, and software decisions made before a traveler reaches the podium.
The clearest signal came from American Airlines. American removed carry-on bag sizers from all gate areas systemwide beginning October 6, 2025, according to an internal memo first reported by an aviation industry report on the leaked American memo. The sizers did not disappear. They moved. The metal frames now sit in airport lobbies and at check-in counters, before security, while gate agents are told to use judgment and err toward the customer on close calls.
American Airlines was not the first carrier to do this. American followed United Airlines, which pulled gate sizers from its gates back in 2020 and directed agents to assess carry-on bags by sight, as detailed in trade coverage of the sizer removal and its operational logic. Two of the largest carriers in the United States have now removed the single most visible enforcement tool from the exact spot where most disputes happened.
- What changed: The point of carry-on enforcement, not the size rules
- American Airlines: Gate sizers removed systemwide from October 6, 2025
- United Airlines: Gate sizers removed in 2020, the precedent American followed
- Standard limit: 22 by 14 by 9 inches at American, Delta, United, JetBlue, Alaska
- Automated scanners: Limited testing as of May 2026, not systemwide
Why both enforcement stories point the same direction
A second story has been running alongside the first, and it appears to point the other way. Coverage through early 2026 has described automated bag scanners that measure dimensions to the millimeter and refuse to negotiate. The two stories sit awkwardly together. One set of carriers is removing the gate sizer. Another set of reports describes machines replacing the gate agent’s eye entirely.
Both can be true, because they describe the same underlying move from different angles. The negotiation is not being automated. It is being relocated. Airline carry-on enforcement now favors earlier checkpoints, where lobby and check-in staff flag oversized bags before a traveler clears security, rather than a frame at the boarding door.
Where automated scanning actually stands in 2026
Airline carry-on enforcement, as of May 2026, relies more on bin forecasting and lobby checks than on automated scanners measuring each bag at the gate. United has been testing automated bag scanning at a small number of gates, a measure that could make checks more consistent where it runs. That remains a test, not a network standard.
The technology airlines have actually scaled is different. It predicts. United’s mobile app now includes a Virtual Gate boarding progress tool and navigation features built on machine learning, part of a broader effort to forecast boarding flow and bin demand rather than measure each bag at the door, described in United’s December 2025 announcement of the new app tools. American has separately described using baggage models to predict bag volumes per flight. The pattern across both carriers is forecasting, not gate-level inspection.
What the shift costs and why airlines made it
The system being revealed is a cost decision, not a technology rollout. Gate disputes are expensive in a way that never appears on a fee schedule. The trade group Airlines for America put the average cost of aircraft block time for U.S. passenger carriers at $100.76 per minute in 2024, a figure covering crew, fuel, maintenance, and aircraft ownership. Block time is the clock that runs from pushback at the departure gate to arrival at the destination gate.
Every carry-on argument that delays a door closing burns that number. Removing the sizer from the gate removes the place where the argument starts. Pushing enforcement into the lobby moves the same friction to a point where it costs the airline far less and slows no aircraft. That is the quiet logic underneath a change that reads, on the surface, as a favor to passengers.
What changes for travelers booking summer 2026 flights
For travelers, the practical change is about timing and place. The carry-on question now gets settled earlier, or it does not get settled until the bag is already a problem at the door. A bag that clears the lobby unchallenged can still be gate-checked if the overhead bins fill on a full flight. Gate-checking means surrendering the bag at the boarding door to be carried in the cargo hold and returned at the jet bridge or baggage claim.
The financial exposure sits at the gate, where it is highest. On United, a standard carry-on brought to the gate on a basic economy fare triggers the checked bag fee plus a $25 gate handling fee. The carry-on limit at American, Delta, United, JetBlue, and Alaska remains 22 by 14 by 9 inches, or 45 linear inches counting the sum of length, width, and height, including wheels and handles. Southwest allows slightly more, at 24 by 16 by 10 inches. None of those numbers changed. The enforcement around them did. Travelers comparing the real cost of a ticket can see what every major U.S. airline charges in baggage and gate fees before they book.
- Settle it before security: Test a questionable bag against the lobby or check-in sizer, where a fix still costs nothing.
- Do not expand the bag: An expansion zipper that adds an inch can move a compliant bag past the limit with no frame at the gate to confirm either way.
- Protect the bin window: Boarding position decides whether bin space still exists when a traveler reaches the cabin.
- Move valuables early: Keep medication, electronics, and documents in a personal item, since a gate-check decision now arrives with no time to repack.
The timing matters because summer 2026 is the real test. Bin space is tightest when planes are fullest, and full planes are exactly when a gate agent working without a sizer falls back on judgment and bin availability rather than a frame. A bag that passed in February on a half empty flight is the same bag in July on a sold out one, except the second time there is no overhead room and no sizer to make the call feel neutral. Boarding order decides who reaches the bin first, which is why how each airline assigns boarding groups now carries more weight than it did when a sizer settled the question for everyone.
- Scanner expansion: Whether United moves automated gate scanning from limited tests to a published standard at hub airports.
- Delta and JetBlue: Whether other legacy carriers follow American and United in pulling gate sizers, or hold the line with the frame.
- Summer enforcement tone: Whether full summer flights produce more gate-check decisions now that the neutral frame is gone from the gate.
- Fee movement: Whether gate handling fees rise as airlines push more enforcement value toward the most expensive point in the trip.
The carry-on argument is not ending. Airline carry-on enforcement is being moved to a place and a time where it is cheaper for the airline and easier for the traveler to miss. The gate used to be where a traveler could make a case to a person holding a frame. Increasingly, the case is decided before the traveler arrives, by lobby staff, by software forecasting bin demand, and by how full the flight is. The preparation that protects a carry-on now happens before the airport. A bag built to pass without argument, like the options in this guide to a carry-on that clears the limit every time, removes the only variable a traveler still controls once the sizer leaves the gate.
Did airlines get rid of carry-on size limits?
No. The 22 by 14 by 9 inch limit at American, Delta, United, JetBlue, and Alaska is unchanged. What changed is where carry-on enforcement happens, not the dimensions themselves.
Why did American Airlines remove bag sizers from the gates?
American Airlines removed gate sizers to speed boarding and cut the cost of gate disputes, which burn expensive aircraft block time. The sizers moved to lobbies and check-in counters instead of disappearing.
Are airlines using AI scanners to measure every carry-on bag?
As of May 2026, automated gate scanning is mostly in limited testing, including United trials at some gates. Most scaled airline AI forecasts bin demand and boarding flow rather than measuring each bag at the door.
What does it cost if a carry-on gets gate-checked?
Gate-check costs vary by airline and fare. On United, a standard carry-on brought to the gate on a basic economy fare triggers the checked bag fee plus a $25 gate handling fee.
