Workwear Sets per Wearer: Laundry Cycle, Fleet Size, Wash Life & Yearly Replacement

The formula

This is the expression the tool evaluates. Every term is named underneath, with the unit it must be supplied in.

How the result is derived

Step by step, from the values you type to the figure on screen.

1. The 7 inputs are read from the form on every keystroke: Wearers, Changes per Wearer per Week, Days between Laundry Collections, Laundry Turnaround, Collection to Return, Spare Sets per Wearer, Garment Life in Washes and Garments Lost a Year (Share of Fleet).
2. Each value is checked against the accepted range in the input table below. A value outside its range stops the calculation rather than producing a misleading figure — the results blank out and a message appears.
3. The validated values are substituted into the expression above, which resolves Sets per Wearer together with every supporting figure in one pass — no value is carried over from a previous entry.
4. The supporting outputs — Sets Worn between Collections, Sets Away at the Laundry, Sets for All Wearers, Washes per Garment per Year, Average Garment Life, Sets Worn Out a Year, Sets Lost a Year and Sets to Buy a Year — come from the same pass, so they always describe the same case as the headline figure.
5. Results are rounded for display only. The full-precision value is used throughout the chain, so reading a rounded intermediate figure back into the tool by hand can shift the last digit.

What each input means

Where to read each value on the floor, the unit it must be in, and the range the tool accepts.

What the tool returns

The headline figure and every supporting value it is built from.

Worked example

Substituting

A laundry that came back in three days instead of seven would need 3 sets at the laundry, not 5, and save 100 sets across the fleet.

How to use it

1. Work through the input groups in order — Wearers & Laundry and Wear & Loss. The defaults are a realistic case, so you can change one value at a time and watch what moves.
2. There is no calculate button. Every figure recalculates as you type or drag, which is what makes this usable for a what-if sweep rather than a single answer.
3. Read Sets per Wearer in the dark results panel — that is the headline figure, expressed in sets.
4. Check the supporting rows underneath (Sets Worn between Collections, Sets Away at the Laundry, Sets for All Wearers, Washes per Garment per Year, Average Garment Life, Sets Worn Out a Year, Sets Lost a Year and Sets to Buy a Year) before acting on the headline — they are where an implausible input usually shows itself first.
5. Reset to defaults returns every field to the reference case, which is the quickest way to check whether a surprising result came from the tool or from an input you had changed earlier.

Where this is used

• Process planning — establishing Sets per Wearer before a trial is booked, so machine time and material in Apparel Manufacturing & Garmenting are committed against a calculated figure rather than an estimate.
• Costing and quotation — Sets per Wearer is an input to the cost sheet, and quoting from a worked number rather than a remembered one is what keeps a margin intact.
• Troubleshooting — when the floor result drifts from plan, entering the measured values (starting with Wearers) shows how much of the gap in Sets per Wearer each variable explains.
• Teaching and study — the accepted ranges bracket normal Apparel Manufacturing & Garmenting practice, so moving one variable at a time shows the shape of the relationship rather than a single answer.

Reading the result

Typical bands and what each one is telling you.

Assumptions and limits

• A wearer needs enough sets to last from one collection to the next, enough to cover the sets away at the laundry until they come back, and the spares the contract allows. Change frequency, collection interval, turnaround, wash life and loss are yours or the contract's; the tool has no typical value for them. A year is counted as 52 working weeks. Wear follows the washing, so more sets per wearer make each garment last more years but do not reduce the sets worn out a year; losses run at a share of the fleet. New starters, size changes and leavers are not counted. **Where the garments are PPE, the employer's risk assessment decides when one must be withdrawn, whatever its wash count.**
• Every input is bounded to the range normal practice occupies (Wearers 1 to 100000 people, Changes per Wearer per Week 0.5 to 21 changes and Days between Laundry Collections 1 to 60 days, and so on for the rest). Those bounds are guard rails against typing errors, not a claim that the formula fails one unit outside them.
• The calculation is deterministic: the same inputs always give the same result. It carries no allowance for machine condition, operator skill, ambient conditions or lot-to-lot material variation unless an input above explicitly represents one.
• Nothing is sent anywhere. The maths runs in your browser, so the numbers you type never leave the page.

Standards and further reading

• ISO 15797, Industrial washing and finishing procedures for testing of workwear, for the wash life a garment is tested to.
• The laundry contract and, for protective garments, the PPE standard each one is certified to and its care label.

Questions people ask