The Outfit Math

How 8 to 12 combining pieces cover a month, and what cost per wear shows about a purchase.

The outfit math is the reason a capsule works at all. If every top pairs with every bottom, the number of outfits is the product of the two counts — and that count ignores layering, shoes and accessories entirely. With 5 tops and 3 bottoms that all combine, one gets 15 distinct outfits before any layering is counted.

The combinations grow multiplicatively while the piece count grows linearly. Six tops and four bottoms yield 24 outfits; eight tops and four bottoms yield 32. A set of 8 to 12 combining pieces therefore covers a month of distinct outfits without repeating, which is the practical claim behind the capsule.

Cost per wear is the financial counterpart of the same arithmetic. The purchase price is divided by the number of times a piece is worn, and a basic worn twice a week passes 100 wears within a year. Each additional wear lowers the figure further, which is why pieces that actually combine are the ones that pay for themselves.

The worked example is simple. A piece bought at a given price and worn twice a week reaches 100 wears within a year; the cost per wear is the price divided by 100 at that point, and it keeps falling thereafter. A piece that is never worn has an effectively infinite cost per wear, whatever its price tag said.

The practical use of the math is at the point of purchase. Before buying, work out how many distinct outfits the new piece creates with what you already own, and how many wears a year you realistically expect. The two numbers together tell you whether the piece belongs in the capsule.

The math also explains why the capsule stays small. Because combinations grow multiplicatively, you do not need many pieces to cover a season — which is why a working seasonal capsule runs about 25 to 40 pieces including shoes and outerwear, and why the audit procedure matters more than the shopping list.

• Outfits = tops × bottoms, when every top works with every bottom.
• 5 tops × 3 bottoms = 15 outfits; 6 tops × 4 bottoms = 24 outfits; 8 tops × 4 bottoms = 32 outfits.
• Cost per wear = purchase price ÷ number of wears.
• A basic worn twice a week passes 100 wears within a year.
• A seasonal capsule runs about 25 to 40 pieces including shoes and outerwear.

Further reading

• Audit Your Closet in One Afternoon
• Colour, Fabric and Fit Rules