Does Polyester Shrink? Washing a Polyester Dress

Polyester barely shrinks in a cool or warm wash, because the fiber is set with heat when it's made and doesn't absorb much water. High heat is the risk: a hot dryer or very hot water can shrink it a little, pucker seams or leave a shine, and a polyester blend with cotton or rayon shrinks more than pure polyester.

So if your dress is pure polyester and you wash it cool and dry it gently, it should come out the size it went in. The trouble starts with heat, blends and linings, and that's what the rest of this guide covers.

Why polyester holds its size

Polyester is a synthetic fiber, and it behaves very differently from cotton in water. It absorbs very little moisture, so the fibers don't swell and relax the way cotton fibers do in a wash. That low absorbency is a big part of why polyester keeps its shape and dries fast.

The second reason is how the fabric is finished. Polyester and other heat-sensitive synthetic fabrics are normally heat set at the mill: held at a fixed size and heated, which locks the fibers into that shape. Ordinary wash water stays far cooler than the dry heat polyester is made to withstand, so the fabric stays put.

The catch is that polyester is thermoplastic. It softens when it gets hot enough, and heat after manufacturing can change its size again. A hot dryer, a scorching iron or a radiator is where polyester gets into trouble, not the washing machine. If you're choosing between fibers for a dress you'll wash a lot, our polyester vs cotton dresses guide lays out the trade-offs.

When polyester does shrink

In the dryer

Polyester can shrink in the dryer, and a hot dryer is the one place it's likely to. High heat, plus tumbling while the fabric is damp, can tighten the fibers, pucker seams and leave a slightly crinkled, shiny surface. Tumble on low or delicate, take the dress out while it's still a little damp, or skip the dryer and hang it.

Stretch polyester with spandex or elastane needs even more care. Heat is hard on the stretch fiber, and a dress that comes out of a hot dryer can lose its snap or look rippled.

Blends and linings

Blends are where shrinkage really happens. In a polyester and cotton blend, the cotton can shrink in hot water or a hot dryer, and it pulls the polyester with it. The more cotton in the blend, the more it can shrink.

Rayon, also sold as viscose, shrinks more readily than polyester, so a blend with rayon needs a cooler wash and no dryer. If the label lists rayon or viscose, our guide to what viscose is explains how it behaves.

Linings can catch you out too. A dress with a polyester shell and a cotton or rayon lining can come out of a hot wash with the lining shorter than the outside, so the hem twists or the lining peeks below. Wash lined dresses cool and dry them on a hanger. The care label usually lists the shell and the lining separately, so read both lines before you pick a wash temperature.

How to wash a polyester dress

Follow these steps for a plain polyester or polyester-blend dress:

1. Check the care label first. It overrides everything here. If it says dry clean, do that.
2. Turn the dress inside out. This protects the outer surface and any print from rubbing.
3. Zip it into a mesh laundry bag. It keeps straps from tangling and the fabric from snagging on zippers.
4. Use a cool or warm gentle cycle. Cool is safest for blends, linings and stretch fabrics.
5. Go easy on additives. If the label says no fabric softener, skip it.
6. Air dry, or tumble on low. Hang the dress on a hanger or lay it on a drying rack. If you use the dryer, choose the lowest heat, add a couple of wool dryer balls so the dress doesn't twist into a knot, and take it out slightly damp.

Silk and polyester satin can look alike, but a silk dress needs different handling, so check the label and see our guide on how to wash silk if it's silk. Knit polyester dresses, like many sweater dresses, are fine with the same routine, though a knit should dry flat so it doesn't stretch on a hanger.

Getting wrinkles out without heat damage

Polyester doesn't wrinkle much, which is half its appeal. When it does, steam is the safest fix. Hang the dress and run a handheld steamer over it from a short distance, or hang it in the bathroom while you shower.

If you need an iron, set it to the low synthetic setting, turn the dress inside out and put a pressing cloth (a thin cotton cloth or a clean cotton dish towel) between the iron and the fabric. Too much heat flattens polyester fibers and leaves a shiny patch, and in the worst case it melts a mark into the fabric. Never leave the iron resting in one spot.

Polyester knits can pill where they rub. If yours has started to, here's how to remove pilling from a knit dress.

Shrinking a dress on purpose

If you're wondering how to shrink a dress that's too big, polyester is the hardest fabric to do it with. Because the fiber is heat set, it resists shrinking, and the heat it takes to change it can also pucker seams, melt trims and leave shine marks. Results are uneven at best.

A tailor is the reliable fix. Taking in the side seams, raising the shoulders or shortening the hem changes the fit exactly where you need it, and you get to keep a dress you like.

A cotton dress shrinks more predictably. A hot wash and a hot dryer will often take it down a bit, but you can't control how much or where, and a lined or embellished dress can come out twisted. Only try it on something you'd be fine losing.

And if a dress already shrank in the wash, there's sometimes a partial fix for cotton blends: soak it for about half an hour in lukewarm water with a little hair conditioner, gently stretch the fabric back while it's damp, and let it air dry. It won't always bring it all the way back. For polyester that tightened in a hot dryer, home fixes rarely work, so take it to a tailor to see whether the seams can be let out.