Cost per wear: the only number in your wardrobe that tells the truth

Divide what a garment cost by the number of times you have worn it. That is the whole formula. It has no units anyone argues about, no model behind it, and no marketing department can adjust it — which is why it is the most opinionated number in any wardrobe. It disagrees with almost everyone about what was a good buy. A coat bought for a large sum and worn a hundred winter mornings is one of the cheapest things you own. A dress bought at half price and worn to one wedding is one of the most expensive.

I came to the number the way most people do, by being wrong about my own wardrobe. I would have told you the good coat was the thing I lived in and that the grey cardigan was an afterthought. When I finally counted — and I mean counted, with a tap on a phone each morning, not a guess at the end of the season — the coat was on its ninth wearing and the cardigan on its fortieth. The coat had cost eleven times as much. The cardigan was, by a distance, the better purchase, and I had been about to replace it with something I would wear less.

The reason the number matters more now than it did a generation ago is that the denominator is collapsing everywhere at once. The Ellen MacArthur Foundation’s 2017 report A New Textiles Economy is the most-cited attempt to measure this, and its headline figure is stark: worldwide clothing utilisation — the average number of times a garment is worn before it stops being used — fell by 36% over the fifteen years to 2015. Over the same period, clothing production roughly doubled, driven by a growing global middle class and rising per-capita purchases in mature markets. The report also found that less than 1% of the material used to make clothing is recycled into new clothing, a loss it valued at more than USD 100 billion a year. Put the two facts together and the picture is simple: we buy twice as much and wear each piece a third less, and almost none of it comes back.

It helps to see the number at work on real purchases rather than in the abstract. Take a winter coat at 600 and a printed summer top at 25. Worn ninety times over four winters, the coat runs at about 6.7 per wearing and falling; the top, worn twice before it pilled and was forgotten, sits at 12.5 and will never move. The coat is the frugal purchase and the top the extravagant one, and no amount of looking at the receipts would have told you that. Cost per wear inverts the intuition that price and value are the same thing, and it does so with a division a child could do.

There is a second-order use of the number that I find more interesting than the first. Cost per wear tells you not only which garments were good purchases but which categories are. A wardrobe where the knitwear runs at two per wear and the dresses at forty is telling you where the money should go next season and where it should stop. Most people, asked to describe their wardrobe, describe its contents. Cost per wear describes its behaviour, which is a different and more useful thing to know.

The same arithmetic points at the remedy, and the remedy is not heroic. WRAP, the UK’s waste and resources body, ran a multi-year programme called Valuing Our Clothes and concluded that extending the active life of clothing by just nine months would reduce its carbon, water and waste footprints by roughly 20–30% each. Nine months is not a change of lifestyle. It is wearing the thing you already own a few more times before it is replaced — which is exactly what a rising cost-per-wear figure tells you to do.

Here is where most advice on the subject stops, and where it goes wrong. Cost per wear is usually presented as a shopping heuristic: before you buy, estimate how often you will wear it, divide, and feel virtuous about the cashmere. That is a forecast, and forecasts about our own behaviour are the least reliable numbers we produce. Memory over-counts the pieces we like and forgets the ones we do not. Ask anyone how often they wear their favourite jacket and they will overestimate; ask about the bargain top and they will be surprised it exists. A cost-per-wear figure built on estimated wearings is a story you tell yourself, dressed up as a measurement.

The number only becomes honest when the denominator is a record. That is why ZIMRICS treats Total Wears as a first-class field on every garment — logged the morning it goes on, incremented by the same tap that chooses the outfit — and derives Cost / Wear from it rather than the other way round. The figures the app produces sometimes disagree with the wearer. That disagreement is the point. It is the difference between what you think you wear and what you wear, and the second one is the only version that can improve.

Three habits follow from an honest number, and none of them is about buying less for its own sake. First, buy for the denominator. The garments you reach for weekly are the ones whose gaps are worth filling well; the occasion pieces are where a cheaper purchase costs you nothing, because their cost per wear was always going to be high. Second, repair before replacing anything with a low cost per wear. A garment that has already proven it earns its keep is the best candidate for a new zip or a re-sole, and the worst candidate for the donation bag. Third, read a high cost per wear on an occasion piece as information, not guilt. The interview suit is allowed to be expensive per wearing. What is not allowed, once you have the number, is not knowing.

There is a wider point underneath the arithmetic. The fashion industry’s environmental problem is usually described as overproduction, and it is that. But production follows purchases, and purchases follow the gap between what people own and what they think they need. Most of that gap is not real; it is the unmapped wardrobe, full of clothes their owner has stopped seeing. A wear count closes the gap from the other side. It does not tell you to want less. It tells you, precisely, what you already have — and a person who knows that buys differently without being asked to.

So keep the count. Not for a month of virtue, but because a wardrobe with a real denominator can answer the questions a wardrobe is for: what do I actually wear, what has earned a repair, what was a mistake, and what — honestly — should I buy next. Everything else in fashion analytics is this one column, told back to you in different ways.