The 30-Wear Fashion Value Tool

The 30-Wear Rule

The 30-wear rule, popularised by sustainable fashion advocate Livia Firth, asks one simple question before any clothing purchase: will I wear this at least 30 times? If not, the cost-per-wear is too high to justify. This tool calculates cost-per-wear and applies the 30-wear threshold to any item.

Fast Fashion's Hidden Expense

A low-cost fast fashion top worn 5 times works out far more expensive per wear than a quality piece bought at several times the price but worn 60 times or more — cheaper per use, better quality, and significantly less environmental impact.

The Costs People Often Forget

Purchase price is only part of the picture. Care costs — dry cleaning, specialist washing, repairs — quietly add up over the years. A delicate dress that needs regular dry cleaning could accumulate more in care costs than the original price tag. It can help to factor these in before committing to a purchase. Many people find that once they include ongoing care, the true cost of an item looks quite different from what the label suggested.

Why Occasion Wear Deserves Extra Scrutiny

That wedding guest outfit worn once. The party jumpsuit still in its bag. Occasion wear is where cost-per-wear can quietly spiral. This is worth noting when the temptation is to buy something new for every event. One approach is to calculate the cost-per-wear upfront — sometimes the numbers alone are enough to prompt a rethink, whether that leads to renting, borrowing, or simply reaching back into the wardrobe.

A worked example

Try the defaults: item purchase price of 60, times you expect to wear it of 25, annual care cost of 10, years you expect to own it of 3. The tool returns 1.20. You can adjust any input and the result updates as you type — no submit button, no reload. That's the real power here: seeing how sensitive the output is to one or two assumptions.

What moves the number most

The result responds to Item Purchase Price, Times You Expect to Wear It, Annual Care Cost (dry cleaning etc), and Years You Expect to Own It. Not every input has equal weight. Adjusting one input at a time toward extreme values shows which ones move the result most.

The formula behind this

This calculator estimates potential savings and payback periods based on typical usage patterns and the inputs provided. Actual results depend on local pricing, climate, usage habits, and other factors. Results are for illustrative and educational purposes only. Everything the calculator does is shown in the formula box below, so you can check the math against your own spreadsheet if you want.

Running the sensitivity

Energy prices, usage patterns, and grant availability all move the payback figure. Test at least two scenarios — current rates and a rate 20% higher — to see whether the decision holds up across plausible futures.

What this doesn't capture

Carbon reduction, health benefits, and local air quality have real value the financial figure doesn't price. The calculation gives the money side honestly; for the full picture, note the non-financial benefits alongside.