How to Wash a Wool Sweater Without Shrinking It

To wash a wool sweater without shrinking it, use cold or lukewarm water (around 30 °C at most), a detergent made for wool, and as little agitation as possible: soak for a few minutes, squeeze gently, rinse in water of the same temperature, press out the water in a towel and dry it flat away from heat. In a machine, only use a wool or hand-wash cycle with a low spin — and only if the care label allows machine washing.

Wool is durable and naturally resists odor, so a sweater that is cared for well can last for many years. Most ruined sweaters come from one mistake: heat combined with movement. Here is how to avoid it.

First: read the care label

The label is the most important instruction. Look for:

Symbol	What it means for your sweater
Tub with a hand	Hand wash only
Tub with 30 and two bars	Machine wash allowed on a very gentle cycle, maximum 30 °C
Crossed tub	Do not wash at home; professional cleaning
Square with horizontal line	Dry flat
Crossed square with circle	Do not tumble dry

Not sure what a symbol means? See laundry symbols explained.

Why wool shrinks (and how to prevent it)

Wool fibers have a scaly surface. When warm water, agitation and pressure work on them, the scales catch on each other and the fibers lock together permanently. This is called felting, and it makes the sweater smaller, thicker and stiffer.

Three things trigger it:

1. Heat — hot water or a hot dryer.
2. Agitation — rubbing, wringing, a normal machine cycle.
3. Temperature shock — moving from warm to cold water quickly.

Some wool is treated to be machine washable, but even then a gentle cycle is recommended. Untreated wool, cashmere and alpaca need the most care. For more on the different animal fibers, see the clothing fabrics guide.

How to hand wash a wool sweater

You need a clean basin or sink, wool detergent, and one or two large towels.

1. Turn the sweater inside out. This protects the surface from friction.
2. Fill the basin with cold or lukewarm water — comfortable on your hand, not warm. Add the amount of wool detergent stated on the bottle and swish to dissolve it.
3. Submerge the sweater and press it gently under the water. Do not rub.
4. Soak for about 10 minutes, or as the detergent instructions say.
5. Squeeze gently a few times to move water through the fibers. Again, no rubbing or twisting.
6. Drain and rinse in clean water of the same temperature until no suds remain. Some wool detergents are designed to be left in; check the bottle.
7. Press out water by pressing the sweater against the side of the basin. Never wring it.
8. Roll it in a towel. Lay the sweater flat on a dry towel, roll the two up together like a sushi roll, and press to absorb water.
9. Dry flat. Lay it on a fresh dry towel or a flat drying rack, reshape it to its original size and let it dry away from radiators and direct sunlight. Turn it over once to speed up drying.

How to machine wash a wool sweater

Only if the label allows it.

1. Turn it inside out and place it in a mesh laundry bag.
2. Choose the wool or hand-wash cycle, which uses minimal agitation.
3. Set the temperature to cold or 30 °C at most.
4. Use a low spin — or the lowest the wool cycle allows.
5. Use wool detergent, without fabric softener unless the detergent maker recommends it.
6. Do not overfill; wash knitwear with a few similar items or alone.
7. Remove promptly and dry flat as described above.

Detergent: what to use

Use	Avoid
Detergents labeled for wool or delicates	Regular powders with strong enzymes, which can damage protein fibers
Mild, pH-neutral formulas	Bleach of any kind
Small doses	Too much detergent, which is hard to rinse out

Wool and silk are protein fibers, which is why enzymes designed to break down protein stains can weaken them over time.

How often to wash

Wool needs washing less often than cotton. Between wears:

• Air it on a hanger near an open window for a few hours, then fold it away.
• Brush it with a soft clothes brush to remove dust and surface lint.
• Spot clean small marks with a little wool detergent and cool water.

A reasonable rhythm is to wash when the sweater is visibly dirty, stained or no longer smells fresh — and before storing it for the summer.

Pilling: why it happens and what to do

Pills are small balls of tangled fibers that form where the fabric rubs: under the arms, on the sides, on the cuffs. They are normal, especially in soft, loosely spun wools and cashmere, and they usually reduce after the first months as loose fibers work their way out.

• Remove pills with a cashmere comb, a fabric shaver or careful snipping with small scissors.
• Work on a flat surface, gently, in one direction.
• Do not pull pills off by hand — that drags more fibers out.

Storing wool sweaters

• Fold, never hang, to avoid stretched shoulders.
• Store clean: moth larvae feed on keratin and are attracted to residue such as food and perspiration.
• Use breathable storage such as cotton bags or boxes, not sealed plastic for long periods.
• Add cedar or lavender as a deterrent and check stored wool regularly.
• Give it space so the knit is not crushed.

A care routine at a glance

• Read the care label first
• Air and brush between wears
• Wash cold or lukewarm with wool detergent
• No rubbing, wringing or temperature changes
• Roll in a towel, then dry flat away from heat
• De-pill with a comb or shaver
• Fold and store clean, with moth protection

Common mistakes

Using a normal cycle. Agitation and spin on a standard cycle are the main cause of felting in machine-washed wool.

Hot water "for hygiene". Wool does not need hot water to get clean, and heat is what shrinks it.

Wringing. It stretches wet fibers out of shape. Press and roll in a towel instead.

Drying on a radiator or in the sun. Direct heat can shrink, stiffen or yellow wool.

Hanging wet knitwear. The weight of water pulls the sweater longer and stretches the shoulders.

Why good care pays off

A wool sweater cared for gently can stay in your wardrobe for many seasons, which lowers its real cost. If you are deciding between a cheaper acrylic sweater and a wool one, the cost per wear calculator lets you compare them, including the small yearly cost of wool detergent and a de-pilling comb.

Washing wool is less about effort than about avoiding heat and friction. Cool water, a gentle touch and flat drying are all it takes.