Cold-weather clothing is bulky, so a good carry-on strategy is built around layers rather than multiple heavy outfits.
Wear the bulkiest pieces
Travel in your heaviest shoes, coat or thick layer when practical. This immediately frees valuable suitcase space.
Build a three-layer system
Pack lightweight base layers, a small number of warm mid-layers and one reliable outer layer. Repeating the outer layer is much more space-efficient than packing several jackets.
Compress soft items carefully
Use packing cubes to contain knitwear and soft layers while keeping categories separate.
Choose accessories with high value
A hat, scarf and gloves take little space compared with another sweater and can make the same outfit work in different conditions.
Keep indoor clothing lighter
Remember that much of your time may be spent in heated spaces. Avoid packing every outfit as if you will be outdoors all day.
Layering gives a small bag much more flexibility.