No, on almost all commercial airlines in 2026, a jacket or coat does not count toward your personal item or carry-on allowance. Standard aviation policy allows passengers to bring a jacket, an umbrella, a diaper bag, and duty-free goods in addition to their allotted bags. This is a vital "travel hack": if your carry-on is slightly overweight or full, you should wear your heaviest layers onto the plane. Once you are past the boarding gate and inside the aircraft, you can usually take the jacket off and place it in the overhead bin on top of the bags or hold it in your lap. Some ultra-low-cost carriers like Spirit or Ryanair are notoriously strict about bag sizes, but even they generally permit a jacket worn on the body. However, if you are carrying a "jacket" that is actually a bulky "wearable luggage" vest with 20 pockets full of heavy electronics, a gate agent might flag it as an extra bag. As long as it functions as a standard piece of clothing, you are free to bring it on board without penalty.