The 5-4-3-2-1 packing rule is a formula for mixing and matching clothes in a carry-on. The numbers stand for 5 tops, 4 bottoms, 3 pairs of shoes, 2 dresses, and 1 set of accessories. Fifteen pieces total, usually enough for a 10 day trip.
The method was created by blogger Geneva Vanderzeil in 2015 for a trip to Greece and went viral again on TikTok in 2024.
The math works because every piece is designed to match every other piece. Five tops times four bottoms produces 20 base outfits, before adding dresses or layering variations. The three shoes cover walking, dressier wear, and sandals or flats.
Where it fails: if the pieces do not coordinate in color or formality, the rule produces 15 separate outfits instead of 20+ combinations.
See: how to build a travel capsule wardrobe and best packing cubes for this setup.