Does Polyester Shrink? What Actually Happens in the Wash and Dryer

Short answer: polyester barely shrinks in a normal wash and dryer. The fiber is heat-set at the mill, so everyday laundry temperatures do not change its size much. Real heat is what hurts it: a dryer on high, a hot iron or a heat press held too long can pucker, shine or distort polyester. When a "poly" shirt shrinks, the cotton or rayon in the blend is usually the reason.

We print and stitch on polyester, cotton and blends, so here is what actually happens in the laundry, and what it means for a shirt with your logo on it.

Why Polyester Holds Its Size

Polyester is a thermoplastic fiber. It softens with heat and holds whatever shape it cools in. Mills use that on purpose. After knitting or weaving, the fabric is run through a step called heat setting: it is held at a set width and heated hot enough to relax the internal stress left from spinning and knitting, then cooled in that shape.

Textile references put polyester heat setting in the range of about 170 to 220°C, held for roughly 15 to 60 seconds, and say properly heat-set fabric should show less than 1% leftover shrinkage after a boiling water test (source: Textile Learner, heat setting process parameters). A home washer and dryer run far cooler than that, which is why a polyester shirt comes out the same size it went in.

The same source notes the set holds until the fabric is exposed to temperatures above the heat-setting temperature. You will not hit that in a normal dryer, but you can get close to trouble with an iron on the cotton setting or a heat press.

When Polyester Can Shrink or Distort

• Very high dryer heat, over and over. Not a big size change, but you can get puckered seams, set-in wrinkles and a stiffer hand, especially on thin knits.
• A hot iron. Polyester can glaze, go shiny or melt at the iron's cotton setting. Use the synthetic setting or a press cloth.
• A heat press used wrong. Too hot or too long leaves press marks and can scorch or warp the fabric.
• Poor-quality fabric. A garment that was not fully heat-set at the mill can shrink more than you expect. Good blanks from known brands rarely have this problem.

So the honest answer to "does polyester shrink?" is: not in normal care, but it does not like high heat.

Cotton, Blends and Tri-Blends Compared

Cotton is a different story. Cotton yarn is stretched under tension as it is spun and knit. When it gets wet and tumbles warm, the fibers swell and relax back toward their natural length, and the shirt gets shorter. That is why the first hot wash and dry does most of the damage on a 100% cotton tee.

In general, the more polyester in the blend, the less a shirt shrinks. A 50/50 fleece like the Gildan 18500 hoodie holds its size better than a 100% cotton tee like the Gildan 5000. Exact shrink depends on the knit and the finish, so no chart can promise a number. You can compare the actual measurements of both on our Gildan size chart, and every other blank we print on the size charts hub.

Picking a fabric for a new design? Our guide to choosing the best t-shirt material walks through cotton, poly and blends for printing.

How to Wash Polyester So It Lasts

• Wash cold or warm, inside out.
• Tumble dry low, or hang dry. Pull it out while it is barely damp to skip wrinkles.
• Skip fabric softener on performance shirts. It can coat the fibers and dull the moisture wicking.
• Iron on the synthetic setting, or not at all. Never iron directly on a print.
• Wash with like fabrics. Polyester grabs lint from cotton towels.

Got cotton or a blend? The same routine works and cuts shrink a lot. For printed and embroidered gear specifically, see how to care for screen printed and embroidered apparel.

What This Means for Printed Shirts

Polyester's heat sensitivity matters more at the print shop than in your laundry room. Two things to know:

• Dye migration. Polyester is colored with dyes that can turn to gas when heated and bleed up into the ink. A white or light print on a red or black poly shirt can turn pink or gray. SanMar's dye migration white paper says low-cure inks for polyester generally cure around 290 to 320°F, some as low as 250°F, and recommends a bleed blocker base on polyester, blends and tri-blends (source: SanMar screen printing dye migration white paper).
• DTF on polyester. DTF transfers work well on poly, but the press settings matter. Too much heat or time can leave press marks or scorch the fabric. Our guide on how to press DTF transfers covers settings and troubleshooting.

That is why we ask what the garment is made of before we quote. A polyester performance shirt usually calls for a low-cure ink with a bleed blocker, or a DTF transfer, rather than the same setup we would use on a cotton tee.

Frequently Asked Questions

Does 100% polyester shrink in the dryer?
Not much on normal or low heat. Polyester is heat-set at the mill, so a home dryer does not change its size in a meaningful way. Very high heat can still cause puckering, wrinkles or distortion.

Can you shrink a polyester shirt on purpose?
Not reliably. It takes more heat than a home dryer gives, and getting close to that heat tends to damage the fabric before it shrinks evenly.

Do cotton/polyester blends shrink?
Some, but less than 100% cotton. The cotton part can relax and shrink while the polyester part helps the shirt hold its shape.

Do tri-blend shirts shrink?
A little. The polyester is stable, but the rayon and cotton can shrink or twist if washed hot and dried on high. Wash cold and dry low.

Will the print on a polyester shirt crack or fade in the wash?
A print cured correctly with the right ink holds up well. Wash inside out in cold water and dry low to make it last.

Should I size up in polyester shirts?
Usually no. Polyester holds its size, so order the size that fits now. With 100% cotton, some people size up to allow for shrink.

Ready to print? Tell us the garment, colors and quantity on our request a quote page and we will match the ink to the fabric. For moisture-wicking polyester tees, see custom Dri-Fit shirts.