Why do clothes shrink in the wash, and how can you prevent it?

Why do clothes shrink in the wash, and how can you prevent it?

A team garment shrinks less when you know how to dry it. It shrinks in the wash when its cotton fibres swell in water then tighten, and when its knit, pulled during manufacturing, gets shorter. The tumble dryer releases all of that shrinkage: follow each model's care label.

Clothes that shrink in the wash are the bad surprise dreaded by anyone ordering custom clothing for a team, a club, an association or a brand's community: sweatshirts and hoodies that fit perfectly on handover day, sleeves that creep up after a few machine washes. Yet shrinkage is no accident. It depends on the fibre, on how the fabric was knitted then finished at the mill, and on how it is washed and, above all, dried. Here is what happens in the machine, which materials move the most, what our product pages tell you before you order, and how to wash your merch afterwards.

Why do clothes shrink in the wash?

A cotton garment shrinks in the wash for two reasons that add up: the fibre swells in water then tightens as it dries, and the knit, pulled during manufacturing, returns to a shorter shape. Cotton Incorporated, the organisation of the American cotton industry, describes this mechanism loop by loop in a 2004 technical bulletin: wetted without tension, each loop of the knit seeks a rounder shape, and a loop that rounds out gets shorter.

So the fabric reaches you with shrinkage in reserve. At the mill, dyeing, extraction and drying pull on the fabric, most often lengthwise: when a knit is extracted, a length stretch of 10% or more is commonplace, according to the same bulletin. That tension then relaxes in your machine. Technicians call it residual shrinkage, what is left in the fabric when you buy it.

Why does a t-shirt shrink more than a shirt?

A t-shirt, a sweatshirt or a polo shrinks more easily than a shirt because it is knitted, loop after loop, whereas a shirt is woven, warp thread against weft thread. Cotton Incorporated makes the point in another bulletin, from 1999: whatever their construction and fibre blend, knitted fabrics are inherently more prone to shrinkage than wovens, which are far more stable.

Is it the heat or the tumble dryer that makes clothes shrink?

For a cotton garment, it is the tumble dryer itself, not its temperature setting: tumble drying until dry releases all the shrinkage held in reserve. Cotton Incorporated tumble dried the same 100% cotton knit at 38, 66 and 94 °C: the shrinkage curves were identical at all three temperatures. The fabric tightens mostly at the end of drying, once it falls below 20% moisture.

The organisation draws the consequence for the care label. A garment dried on a line or flat mostly goes through the release of its manufacturing tensions; a garment that goes in the tumble dryer goes all the way with its shrinkage.

Washing temperature matters to brands too. In its cotton care guide, Stanley/Stella advises washing its 100% organic cotton garments "ideally 30°C or a cold wash setting" to prevent excessive shrinkage, then laying them flat or hanging them to dry, with no tumble dryer, which in its words "puts stress on the fabric's structure and leads to shrinkage or distortion".

Do clothes shrink from the first wash?

Yes: most of a cotton garment's shrinkage happens at the first wash followed by drying. According to Cotton Incorporated, a single cycle may remove around 90% of the shrinkage available, even if several cycles are sometimes needed to reach the final size. A garment measured before and after a first full cycle has therefore already shown most of its shrinkage.

Which materials shrink the most in the wash?

In the wash, cotton and wool can shrink, each in its own way; polyester does not go through the swelling that makes cotton shrink. Cotton Incorporated explains it: thermoplastic synthetic fibres can be stabilised by heat setting, which cotton cannot be, and they do not swell in water.

Wool shrinks differently from cotton. The Woolmark Company explains that its fibre carries tiny scales: with heat and moisture they lift, then the rubbing of the machine locks them onto one another, in a ratchet-like way. This felting makes the fabric denser, and it is irreversible. Wools sold as machine washable have been treated to modify those scales. The product page of the Tee Jays merino jumper, for its part, asks for a 30 °C wash on the wool programme.

Does a thicker fabric shrink less?

For a given yarn, a tighter, and therefore heavier, knit shrinks less in length but more in width: Cotton Incorporated notes that a smaller knitted loop gives a heavier, more stable fabric. That weight of fabric per square metre appears on the product page: our guide to heavyweight t-shirts shows what it corresponds to.

Spinning, on the other hand, changes little: Cotton Incorporated finds no significant difference in length shrinkage between ring-spun and open-end yarns. On a product page, ring-spun describes how the cotton is spun, which our page on combed cotton covers, not a treatment against shrinkage.

Shrinkage is not the only flaw that washing reveals: pilling, those little balls of fibre that appear on the surface, has its own causes and its own fixes.

What should you read on a product page to know whether a garment will shrink?

To know whether a garment is likely to shrink, look for three clues on its product page: the composition, the care instruction and the words "pre-shrunk" when they appear. On tknp.io, these clues are not in the same place for every brand: among more than a thousand product pages read in their French version on 21 October 2026, a care line only appears on Stanley/Stella pages, while on Tee Jays pages a washing temperature sometimes appears in the description.

• The composition tells you the share of cotton, polyester or wool, and so which shrinkage mechanism is at play.
• The care instruction gives the brand's washing advice, and sometimes a temperature.
• The words pre-shrunk appear in the description of some pages: the Tee Jays Sof Tee page says "Pre-shrunk cotton. Machine washable at 60°C."

What does "pre-shrunk" mean on a product page?

"Pre-shrunk" announces a fabric treated at the mill so that it shrinks less at home, not a fabric that will never shrink at all. On tknp.io, none of the 78 product pages that carry the mention in their French version says how much the garment may still shrink. The only published measurements we have read date from 2004: on a 100% cotton jersey that went through tension-free drying, compaction or a chemical finish, Cotton Incorporated still recorded 4.5 to 7.3% shrinkage in length and 3.5 to 6% in width, after five washes each followed by tumble drying; they say nothing about any specific model on our product pages.

Some manufacturers even build shrinkage into their pattern. The product page of Gildan's 2000 PFD t-shirt, designed to be dyed again, announces "increased body and sleeve length to compensate for shrinkage during overdyeing".

How do you wash clothes so they don't shrink?

To keep a cotton garment's shrinkage to a minimum, follow its model's care label: wash at a low temperature, without exceeding the one on the label, reshape the garment while still damp, and dry it flat or on a line whenever the label rules out the tumble dryer. For its 100% organic cotton garments, Stanley/Stella's care guide rules it out; Cotton Incorporated's measurements explain why cotton shrinks the most in the tumble dryer.

1. Read the care label before the first wash: its symbols give the temperature and the drying allowed.
2. Wash cool: Stanley/Stella advises 30 °C, or even cold, and the care symbols of the Creator 2.0 on its website show 30 °C. Some product pages allow a hotter wash: the Tee Jays Sof Tee page, in pre-shrunk cotton, gives it as washable at 60 °C.
3. Reshape the garment while still damp, as Stanley/Stella advises, before drying it.
4. The tumble dryer, only if the label allows it: it releases all the shrinkage held in reserve. The care symbols of the Creator 2.0 rule it out; conversely, B&C's Perfect Pro, a 185 g/m² t-shirt, accepts it according to its tknp.io product page, which also gives it as washable at 60 °C.
5. For wool, choose the wool programme: 30 °C for the Tee Jays merino jumper.

The logo, for its part, has its own care rules depending on its technique, gathered in our article on washing vinyl and printed t-shirts.

Should you size up to allow for shrinkage?

Nothing supports advice to size up: no tknp.io product page, out of more than a thousand read in their French version on 21 October 2026, recommends it to make up for washing, and Stanley/Stella's care guide does not mention it. If the team already wears this model, measure one garment instead, before and after a first full wash, done the way your members will do it.

Choosing a roomy cut is another matter: an oversized cut is not one size up, and our guide to cuts explains the difference. Deciding before the run matters too: a custom garment is neither taken back nor exchanged over a size issue, as our terms of sale state.

Send the care instruction with the Store pre-order

Before you send your campaign link on the tknp.io Store, attach the model's care instruction, read on its label or in its brand's care guide (for the Creator 2.0, on the Stanley/Stella website): everyone will know how to wash and dry their custom t-shirts or sweatshirts from the first cycle, the one that accounts for most of the shrinkage. To read these instructions and share them with the team, see our guide to care symbols. Reserved for verified pro accounts, the Store runs pre-orders lasting 7 to 21 days, during which everyone chooses their own size; our guide to collecting your team's sizes explains how it works. The Store is free to open, and the campaign free to publish.