Short answer
Synthetic fabrics such as polyester, nylon and acrylic generally resist shrinking in normal washing and drying. They absorb little water, and they are typically heat-set during manufacturing so they hold their shape. They are not immune, though: very high heat can warp, tighten or damage them, and blends with natural fibers can still shrink.
Why synthetics resist shrinking
Synthetic fibers are made from petroleum-based polymers, which are formed into filaments and usually heat-set. They absorb much less moisture than cotton, so they do not swell and relax the same way when wet. That is a large part of why polyester shirts, sportswear and many linings keep their size through repeated washing.
Common synthetic fibers
- Polyester: very common, durable and quick to dry.
- Nylon: strong and smooth, used in activewear and hosiery (see is nylon fabric good or bad).
- Acrylic: wool-like, used in knits and blankets.
- Spandex or elastane: stretchy, usually blended in small amounts (see uses of Lycra fabric).
Care labels differ between these, so follow the label for each item.
Heat can still change them
“Does not shrink” is not the same as “cannot be damaged.” Hot dryers, hot irons and very hot water can cause synthetics to pucker, warp, lose stretch or in some cases melt slightly. Elastic fibers are sensitive to heat, and a garment can feel tighter or looser afterward. Using cool or warm water and low dryer heat is the safe default.
Blends
Mixed fabrics usually shrink according to their natural fiber content. A cotton-polyester shirt will often shrink less than 100% cotton, but the cotton part can still contract and the garment may twist or change shape (see cotton vs cotton polyester blend and is poly cotton soft). For a 60% cotton, 40% polyester shirt, a hot dryer can cause some shrinkage, so low heat is wise. For how cotton behaves, see cotton in the wash, and for a dense woven example, cotton twill.
Rayon and viscose
Rayon and viscose are often grouped with synthetics, but they are made from regenerated plant cellulose, which makes them semi-synthetic. They absorb water and can shrink noticeably, so do not assume they behave like polyester. See polyester vs rayon for the differences and ironing viscose fabric for care.
Can you shrink polyester on purpose?
It is difficult and often uneven. Some guides describe washing in warm water and drying with moderate heat, but results are limited and heat risks damaging the fabric. If a polyester garment is too large, a tailor is usually a safer option than trying to shrink it.
Disadvantages of synthetics
- Less breathable than many natural fibers.
- Can hold odors.
- Can build up static or pill (see fabrics that don’t pill).
- Sensitive to high heat.
- Concerns about microplastic shedding when washed.
They also have advantages, such as durability, quick drying and low cost, so the best choice depends on the use.
FAQ
Do synthetics shrink in the dryer? Usually very little at normal settings, but high heat can damage them.
Can I shrink linen? Linen is a natural fiber and does shrink with heat. See our cotton-linen guide.
Does spandex shrink? It can lose stretch or tighten with heat, so wash it gently.