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Why Sweaters Pill and How to Stop It

Why sweaters pill, which fibres pill most, how to prevent it, and how to remove pills safely.

By Alex Carter  |  Published 2026-10-04  |  Fabric & Quality  |  Updated November 2026

Pilling is the small balls of tangled fibre that appear on the surface of a sweater, usually under the arms, along the sides, and wherever the fabric rubs against itself, a bag strap, or a seatbelt. It is one of the most common reasons a sweater stops being worn — not because it is worn out, but because it looks worn out. The good news is that pilling is understandable, largely preventable, and fixable when it happens. This guide explains why sweaters pill, which fibres pill most, how to prevent it, and how to remove pills safely without damaging the garment.

First, an important reassurance: pilling is not proof that a sweater is cheap, and the absence of pilling is not proof that a sweater is good. Some of the finest natural fibres in the world — cashmere, merino wool, angora — pill more than cheap synthetics, because their fibres are short, soft, and loosely held. A sweater that never pills may be made from long, strong synthetic fibres that simply do not break and tangle. So do not judge a sweater by pilling alone. Judge it by how it pills, how easily the pills can be removed, and whether the fabric underneath still looks good after the pills are gone. Our fabric guide explains how fibre length, twist, and weave affect durability, and it is a useful companion to this guide.

Why sweaters pill: the mechanics

Pilling happens in three stages. First, friction — from wearing, washing, or rubbing against another surface — loosens short fibres from the yarn and brings them to the surface. Second, those loose fibres tangle together into a small ball. Third, the ball anchors itself to the fabric by a few unbroken fibres, so it stays attached instead of falling off. The shorter and weaker the fibres, the faster this happens. The more friction, the faster it happens. And the looser the yarn twist, the easier it is for fibres to escape.

That is why the worst pilling usually appears in the first few weeks of wear, and then slows down: the loosest fibres come out first, and once they are gone, the remaining fibres are held more firmly. A new sweater that pills heavily in its first month is not necessarily a bad sweater — it may simply be shedding its loosest fibres. The test is what happens after you remove the pills: if the fabric looks good and the pilling slows, the sweater is fine. If the pilling returns just as fast every time, the yarn is too weak for the job.

Which fibres pill most — and which pill least

Blends are a mixed picture. A wool-acrylic blend often pills more than pure wool, because the acrylic fibres are strong and hold the pills in place while the wool fibres break and tangle. A wool-nylon blend, by contrast, often pills less, because the nylon adds strength to the yarn. When you shop, check the label and the feel: a tightly twisted yarn with a smooth surface will pill less than a soft, fluffy, loosely spun yarn, whatever the fibre content.

Prevention: how to stop pills before they start

Prevention starts before you buy. In the store, rub the fabric gently between your fingers for a few seconds. If loose fibres come off on your fingers, the sweater will pill. Look at the yarn: a smooth, tightly twisted yarn pills less than a fluffy, brushed yarn. Look at the weave or knit: a tighter knit holds fibres in better than a loose, open knit. And check the label for fibre length clues — "long-staple" or "extra-fine merino" is a good sign, while a very cheap acrylic is a warning sign.

How you wear a sweater matters as much as how it is made. The biggest cause of pilling is friction, and the biggest sources of friction are bag straps, seatbelts, and rough outer layers. If you carry a bag on the same shoulder every day, that shoulder will pill first. Switch shoulders, use a handheld bag, or wear a layer between the sweater and the strap. Avoid wearing a rough jacket directly over a soft sweater without a layer between them. And do not wear the same sweater two days in a row — fibres need time to recover, and a day of rest between wears reduces pilling noticeably.

How you wash a sweater matters most of all. Turn the sweater inside out before washing, which puts the friction on the inside surface rather than the outside. Use a gentle or wool cycle, cold water, and a mild detergent. Wash the sweater in a mesh laundry bag, which reduces friction against other garments. Never wash a sweater with rough items such as jeans or towels. And never, ever put a wool or cashmere sweater in the dryer — heat and tumbling are the fastest way to create pills and to shrink the garment at the same time. Our laundry mistakes guide covers washing and drying errors in detail.

How to remove pills safely

When pills appear, remove them — do not pull them off by hand. Pulling a pill by hand pulls the anchoring fibres with it, which loosens more fibres and creates more pilling next time. It can also pull a thread and create a hole. Use a proper tool instead.

The best tool for most sweaters is a fabric shaver, a small electric device that shaves pills off the surface without cutting the fabric. It typically costs around $10 to $25, it works on wool, cashmere, cotton, and synthetics, and it is the single best investment for anyone who owns knitwear. Use it on a flat surface, with the sweater laid flat and smoothed out, and move the shaver in light, even passes. Empty the compartment regularly, and test on an inconspicuous area first.

A sweater stone — a block of pumice-like material — is a good manual alternative, especially for delicate fibres such as cashmere. Rub it gently across the pilled area and the pills gather and can be lifted away. A fine-toothed comb or a clothes brush can also work for light pilling. Avoid disposable razors, which can cut the fabric, and avoid sticky lint rollers for pilling — they remove lint, not anchored pills, and they leave a residue.

After removing pills, the sweater should look close to new. If it does not — if the surface looks thin, patchy, or worn — the yarn has lost too many fibres and the sweater is reaching the end of its life. That is a good moment to consider repair or replacement, and our upcycling guide has ideas for giving a worn sweater a second life.

When pilling is a reason to return a sweater

Some pilling is normal, especially in the first weeks. But there are cases where pilling is a sign of a bad garment and you should return it. Return a sweater if it pills heavily after a single wear in places that had no friction — that suggests the yarn is too weak. Return it if the pills cannot be removed without damaging the fabric. Return it if the fabric underneath the pills looks thin or bare after one removal. And return it if the pilling is accompanied by other defects, such as seams coming apart, uneven dye, or a shape that changes after one wash.

Keep the receipt and the tags until you have worn a sweater a few times. That is the only way to test pilling honestly, and most retailers accept returns within a reasonable window. If you bought the sweater on sale, check whether the return policy is different — some sale items are final sale, which is a reason to be more careful before you buy.

Care routine: a low-pilling sweater habit

• Turn sweaters inside out and use a mesh bag for every wash
• Wash on cold and gentle, with a mild detergent, and never tumble-dry wool or cashmere
• Rest sweaters for a day between wears; do not wear the same one daily
• Keep bag straps and seatbelts off soft knitwear, or add a layer between them
• Fold knitwear instead of hanging it — hanging stretches the shoulders and the knit
• Shave pills with a fabric shaver instead of pulling them off by hand
• Store sweaters with cedar or lavender rather than mothballs, and keep them clean before storage

How to choose, and what to avoid

When you are choosing a sweater, check the yarn first: rub it, look at the twist, and feel whether the surface is smooth or fluffy. Choose tightly twisted, smooth yarns for everyday sweaters you will wear often, and save soft, fluffy yarns for occasional wear. Choose a blend that adds strength — wool with a little nylon, for example — over a blend that adds weakness, such as wool with a lot of cheap acrylic.

Avoid three traps. The first is assuming that a high price means no pilling: cashmere is expensive and pills, and that is normal. The second is assuming that a low price means the sweater is bad value: a well-made cotton sweater that pills a little and lasts for years is better value than a cashmere sweater that pills heavily and is unworn after a season. The third is trying to fix pilling by washing more often — washing creates friction, and more washing creates more pilling. Wash less, wash gently, and shave the pills when they appear. For keeping the rest of your wardrobe in good shape, see our clothing care guide and our winter layering guide.