In 2026, the "largest" standard carry-on size accepted by most major U.S. domestic airlines (Delta, United, American) is 22 x 14 x 9 inches (56 x 35 x 23 cm). This measurement includes wheels and handles, which is a point of strict enforcement this year. However, if you are flying Southwest Airlines, the limit is slightly more generous at 24 x 16 x 10 inches, giving you significantly more volume. For international travel on carriers like British Airways or EasyJet, you can often go up to 22 x 18 x 10 inches. A high-value "pro-tip" for 2026 is that while these are the "legal" limits, the true "largest" bag is one that fits the gate sizer of your specific aircraft; regional jets often have much smaller bins, and even a "legal" 22-inch bag may be gate-checked for free if the bins are full, so it’s always best to target the 22x14x9 standard to be safe across all carriers.