The 1-2-3-4-5-6 rule is a popular minimalist packing strategy designed to help travelers fit everything into a carry-on for a trip lasting about a week. The formula suggests packing exactly: 1 Hat, 2 pairs of shoes (wear one, pack one), 3 bottoms (pants, skirts, or shorts), 4 tops (t-shirts, blouses, or sweaters), 5 pairs of socks, and 6 pairs of underwear. This collection creates a "capsule wardrobe" where almost every top can be paired with every bottom, offering at least 12 different outfit combinations. By limiting yourself to these specific numbers, you avoid the "just in case" items that often clutter suitcases. The rule assumes you will wear your heaviest items (like a jacket and boots) on the plane and that you might do one small load of laundry if the trip extends beyond six days. It is particularly effective for 2026 travelers looking to avoid rising checked bag fees and long waits at baggage claim. You can easily adjust the "tops" for the climate—using four light tees for a beach trip or four thermal layers for a winter getaway.