You are charged a fee for this, which is usually more expensive than if you had paid for it in advance. Items which are gate-checked for free are those within the allowance which won't fit in the cabin due to lack of space or because the aircraft has smaller than usual overhead bins.

In 2026, gate checking is generally not more expensive than checking a bag at the ticket counter, and in many instances, it is actually free. Most major airlines, such as United, Delta, and American, will offer to gate-check carry-on bags for free when the overhead bins are full, which is a common occurrence on crowded flights. However, there is a critical exception for Basic Economy passengers on certain airlines like United or JetBlue; if you bring a full-sized carry-on to the gate that is not permitted under your fare class, you may be charged the standard checked bag fee plus an additional "gate handling fee" (often around $25–$65). For travelers on ultra-low-cost carriers like Spirit or Frontier, gate checking is significantly more expensive than paying in advance, as "at-the-gate" bag fees are designed to be punitive. To avoid high costs, it is always best to verify your fare's bag allowance before arriving at the airport. For most standard economy passengers, gate checking is a complimentary "last resort" provided by the airline to speed up the boarding process when bin space runs out.