How to wash a wool jumper without shrinking it
In short: Check the label first. Hand wash inside out in lukewarm water (about 30 °C) with wool detergent, soak for 10 minutes, rinse, squeeze it in a towel without wringing and dry it flat, away from heat. Use the machine's wool cycle only if the label allows.
By Abu Bakar SaadatUpdated 29 October 20265 min readPublisher: Saadat Rafiq
✓ Reviewed by Moaz Abdullah, BS Textile Engineering Technology · 29 October 2026
IllustrationAt a glance
- Water
- Lukewarm, about 30 °C (Woolmark)
- Detergent
- Mild wool detergent
- Never
- Wring, rub, hang it up wet or put it on a radiator
- Dry
- Flat on a towel, reshaped, out of direct sun
- Tumble dryer
- Only with a tumble-dry label, on low or wool
- Advice from
- Woolmark, Which?, Persil and University of Wisconsin-Extension, read 28 October 2026
- Checked
- October 2026
Wool shrinks because of felting. Each wool fibre is covered in tiny scales. Hot water makes them lift, and rubbing plus a change of temperature makes them lock together. The knit then gets smaller and denser, and University of Wisconsin-Extension says it can't be undone. So the rules are simple: keep the water lukewarm, move the jumper gently, and never wring it. Some wool is treated so the scales stay flat, and that wool can go in the machine (UW-Extension); the label tells you.
How to hand wash a wool jumper
Check the label, then turn the jumper inside out.
Illustration A hand in the washing tub means hand wash; a tub with two bars underneath means a very gentle machine programme, such as wool. A crossed tub means don't wash it at all. Our guide to clothing care labels explains every symbol. Then turn the jumper inside out (Woolmark).
Before you wash it the first time, lay it flat and take three measurements: across the chest from armpit to armpit, the body length from the high point of the shoulder (where the shoulder seam meets the collar) down to the hem, and the sleeve length. Write them down, so you can compare afterwards.
You should see: the jumper inside out, with the seams on the outside, and its three measurements written down.
Careful: hot water and rubbing are what make wool felt and shrink (UW-Extension). Keep the water lukewarm and don't rub or scrub.
Soak it for 10 minutes in lukewarm water with wool detergent.
Illustration Fill a basin with clean, lukewarm water, about 30 °C (Woolmark), and add a little wool detergent; Persil says liquids work best. Put the jumper in and swish it gently without stretching it (Persil). Leave it to soak for 10 minutes (Woolmark, Persil, Which?).
For a stain, dab a little diluted wool detergent onto it before washing (Which?).
You should see: the jumper fully under the water, soaking, with no rubbing needed.
Rinse until the water is clear.
Illustration Rinse first in lukewarm water, then in cold (Woolmark). Change the water as often as you need to remove all the detergent (Persil).
You should see: clear rinse water, with no suds left.
Careful: never wring it. Wringing stretches the knit and damages the fibres (Persil, Which?).
Squeeze the water out by rolling it in a towel.
Illustration Ball the jumper up and press gently over the sink. Lay it flat on a dry towel, roll the two up together and squeeze as you roll. Then move it to a second dry towel (Which?).
You should see: a damp jumper, no longer dripping, still in its original shape.
Dry it flat and ease it back into shape.
Illustration Lay it flat on a pale, lint-free towel and gently ease it back into shape and size with your hands (Woolmark). Keep it away from direct sun, sunny windows and radiators (Woolmark).
A warm room is best; Which? found a dehumidifier in the room almost halved the drying time.
You should see: the jumper lying flat, smoothed out to its usual shape, away from heat.
How to tell it worked
- The dry jumper measures the same across the chest, down the body and along the sleeves as before you washed it.
- It still feels soft. A jumper that feels thick and stiff has felted (UW-Extension).
- It hasn't stretched out of shape, as it can when hung up wet (Woolmark, Which?).
- There's no fluff from the towel on it (Woolmark).
Machine washing and drying: what the sources say
| Method | What to do | Source |
|---|---|---|
| Hand wash | About 30 °C, soak 10 minutes, rinse lukewarm then cold | Woolmark, Persil |
| Machine, only if the label allows | Wool cycle, inside out or in a laundry bag. Woolmark says the wool setting is usually a gentle 40 °C; Persil says 30 °C or less. Without a wool cycle: cold or delicates (Woolmark), at 30 °C or below (Which?). Follow the label | Woolmark, Persil, Which? |
| Dry flat on a towel or airer | Best option for knitwear | Woolmark, Which? |
| Heated airer | Fine, laid flat across it rather than over the bars; it doesn't get hot enough to shrink wool | Which? |
| Hanger or washing line | Avoid: knitwear stretches out of shape | Woolmark, Which? |
| Radiator or direct sun | Avoid | Woolmark |
| Tumble dryer | Only with a tumble-dry label, on low heat or a wool setting (Woolmark). In Which?'s test of six dryers, five programmes shrank jumpers by more than 5 cm in at least three places, and drums reached 85 °C | Woolmark, Which? |
If something goes wrong
| What happens | What it means | What to do |
|---|---|---|
| It shrank and feels thick and stiff | It has felted, which UW-Extension says can't be reversed | It may still fit a child, or make a felt craft project. Next time, avoid hot water and rubbing |
| It stretched | It was probably hung up wet | Wash it again and dry it flat, easing it back into shape |
| Fluff on a dark jumper | The towel shed lint | Use a pale, lint-free towel (Woolmark) |
Questions readers ask
Can I use normal washing detergent?
Use a wool detergent. Woolmark recommends a neutral, mild detergent, and Persil's wool page recommends a gentle, pH-neutral wool detergent.
Can I hang a wet jumper on a hanger or washing line?
No. Woolmark says hangers and line drying can stretch knitwear, and Which? says the same. Dry it flat.
My jumper has already shrunk. Can I fix it?
If the wool has felted, no: University of Wisconsin-Extension says felting can't be undone. Next time, avoid hot water and rubbing.
Is it safe to tumble dry wool?
Only if the label allows it. Woolmark says garments with its tumble-dry claim can go on low heat or a wool setting. In Which?'s test, five of six dryer programmes shrank jumpers by more than 5 cm in at least three places.
Sources
We base our articles on the makers' official documentation.
