Fitting three weeks of clothes into a standard 22" carry-on is entirely possible in 2026, but it requires a "minimalist" strategy and a commitment to doing laundry. The "Golden Rule" for long-term carry-on travel is to pack for one week and repeat. This usually involves 5–7 tops, 2–3 pairs of versatile bottoms (like technical chinos or dark jeans), and enough underwear for 7 days. Choosing fabrics like Merino wool or synthetic blends is essential because they are lightweight, resist odors, and dry quickly after a "sink wash." You should utilize compression packing cubes to remove excess air and organize your items by category. To maximize space, wear your bulkiest items—like your heavy jacket and sturdiest shoes—on the plane. In 2026, many travelers also use "detergent sheets" to easily wash clothes in their hotel or Airbnb. By sticking to a strict color palette where every top matches every bottom, you can create dozens of different outfits from just a handful of pieces, allowing you to travel indefinitely without ever visiting a baggage carousel.