Sizing, Shrinkage and Why Used Clothing Fits Unpredictably

These are listed in the order worth acting on, which with fit and sizing in used clothing is not the order they are usually presented in.

Sizing drift over time

Labelled clothing sizes are not standardised across manufacturers and have shifted over decades, generally in the direction of larger garments carrying smaller numbers. A garment made several decades ago and labelled with a given size will often be noticeably smaller than a current garment with the same label. This affects vintage buying more than anything else and is the most common reason an online purchase arrives unwearable.

The shift is well documented in the trade and is a marketing phenomenon rather than a change in how bodies are measured. The practical implication is that the number on a vintage label carries almost no information at all.

Market differences

Sizing conventions differ between regions, and a garment produced for one market carries numbers meaning something different in another. Used clothing circulates internationally through bulk trade, so a rail in one country routinely contains garments labelled to several conventions. Conversion charts exist and are approximate, because the underlying measurements they convert between were never consistent either.

Sorting the donation bags, labels stating multiple sizes for different markets are the most reliable, since at least the intended measurements were declared. Where the label is missing entirely, which is common in heavily worn garments, the number is simply unavailable.

What laundering does

Natural fibres shrink, and the shrinkage in cotton, wool and linen is largely permanent once it has happened. Wool that has been machine washed felts, reducing dimensions substantially and changing the fabric's character in a way no treatment reverses.

Sorting the donation bags, cotton shrinks mostly in the first few washes, so a garment washed many times has usually reached its final dimensions and is stable. Synthetics are dimensionally stable but degrade differently, losing elasticity and developing bobbling that indicates age rather than size change. A used cotton garment is therefore more predictable than a new one, which will still shrink after you buy it.

Stretch, sag and the shape it holds

Knitted fabrics stretch in use and relax back only partially, which is why used knitwear frequently sits longer and wider than when new. Elastic in waistbands, cuffs and underwear perishes with age and heat, and no amount of care restores it once it has gone. Garments with elastane lose their recovery over time, so a used stretch garment may fit at first and bag out within an hour.

Leather and suede mould to a previous wearer and retain that shape, which is either an advantage or a problem depending on the item. Shoes in particular carry the previous wearer's gait in the sole and the upper, and that shaping does not fully reverse.

Measuring instead of trusting

Lay a garment you already own flat, measure chest, waist, hip, sleeve and total length, and write the figures down once. Compare those figures against the measurements of anything you are considering, which is the only reliable method when trying on is impossible. Online sellers who list flat measurements are giving you real information; those listing only a label size are passing on a guess.

Sorting the donation bags, ask for a chest measurement across the garment rather than a size, and treat a refusal as informative. For anything tailored, the shoulder seam position matters more than any other measurement because it is the hardest thing to alter.

Tax treatment of donations varies by country and by the way the gift is made.

What can be altered and what cannot

Taking a garment in is straightforward for a tailor; letting it out depends entirely on how much seam allowance the maker left. Older and better-made garments frequently have generous allowances, which is a genuine advantage of vintage tailoring over modern production. Shortening sleeves and hems is routine, though cuff detail, vents and linings complicate it and increase the cost accordingly.

On the shop floor, shoulders can be altered but the work is substantial, which is why the shoulder fit determines whether a jacket is worth buying. Costing the alteration before buying is the step that turns a cheap garment into a genuinely cheap one.

Everything above, in order of what to do first

1. Sizing drift over time. Labelled clothing sizes are not standardised across manufacturers and have shifted over decades, generally in the direction of larger garments carrying smaller numbers.
2. Market differences. Sizing conventions differ between regions, and a garment produced for one market carries numbers meaning something different in another.
3. What laundering does. Natural fibres shrink, and the shrinkage in cotton, wool and linen is largely permanent once it has happened.
4. Stretch, sag and the shape it holds. Knitted fabrics stretch in use and relax back only partially, which is why used knitwear frequently sits longer and wider than when new.
5. Measuring instead of trusting. Lay a garment you already own flat, measure chest, waist, hip, sleeve and total length, and write the figures down once.
6. What can be altered and what cannot. Taking a garment in is straightforward for a tailor; letting it out depends entirely on how much seam allowance the maker left.

The takeaway

Measure a garment you own once, then buy by measurement rather than by label.

Unrestricted money is the most useful gift and the least satisfying to make.