Will Merino Wool Stretch? I Did Some Experiments

Merino wool garments are known for their good quality. They are warm and lightweight, and work great as base layers. But what about their stretchiness? Does merino wool stretch over time? Does the size of a merino wool sweater change after machine-washing?

You will find the answers to all these questions in this article, but here you go if you want a quick answer.

Merino wool does not stretch at all. It does not stretch with daily usage, and it also does not stretch after being washed. However, washing merino wool sweaters in extreme temperatures may lead to shrinking.

To get to this result, I decided to put on a scientist’s hat. I conducted a bunch of experiments on my three favorite merino wool sweaters and recorded the results diligently.

The results were pretty surprising.

Does Merino Wool Stretch Over Time?

wool sweater

To answer this question, I decided to do some research.

I took three different merino wool sweaters I own which are made by popular brands such as Uniqlo, Icebreaker, and Howies. Their costs vary widely, and these three sweaters have been in my arsenal for over 2-4 years now.

I took their current measurements and then compared them with the measurements displayed on their manufacturer’s website, and tabulated the results.

This would help me determine if there had been any change in the size of the sweater, because the manufacturer’s website will show the original size of my garments, and comparing them with the current size would give me the “Change in Size” metric.

This metric would help me decide if my sweaters had stretched or shrunk.

SweaterChange in Size
Uniqlo Merino Wool Sweater2 inches tighter
Icebreaker Merino Wool SweaterNo change
Howies Merino Wool Sweater4-5 inches tighter
Change in merino wool sweater size over time.

As you can clearly see in the table, none of my merino wool sweaters stretched by any amount. Two of them shrunk a bit, as I have washed them multiple times. The Icebreaker merino wool sweater did not have any change in its size.

Through this experiment, I’ve come to a pretty thorough and well-researched conclusion.

Merino wool sweaters do not stretch over time. They won’t stretch even if you wear them every day for the rest of your life.

Okay, maybe that’s an overstatement. I do not recommend you to wear the same sweater for your entire life.

how to stretch merino wool?

Here is the step by step process to stretch merino wool.

  • Step 1: Fill a basin or sink with lukewarm water.
  • Step 2: Gently submerge the wool item in the water, making sure it is fully saturated. Do not wring or twist the wool.
  • Step 3: Gently squeeze out the excess water from the wool item.
  • Step 4: Lay the wool item flat on a towel, shaping it to its original size and shape.
  • Step 5: Use another towel to gently press out the remaining water.
  • Step 6: Let the wool item dry flat, away from direct sunlight and heat sources. Do not hang the wool as it can stretch out of shape when wet.
  • Step 7: Once the wool item is dry, you can use your hands to gently stretch the fibers and reshape the garment.


  • Avoid using hot water, or exposing the wool to heat such as an iron, dryer or heater while stretching it.
  • Wool can shrink when you expose it to hot water and heat, and also it can lose its shape.
  • When washing, always use cold water and mild detergents to clean your wool garment.
  • Remember to be gentle and patient when stretching the wool.

Does Merino Wool Stretch After Washing?

No, merino wool sweaters and garments do not stretch after washing. Some inferior quality pieces might shrink, while others will retain their sizes.

To put this conventional wisdom to test, I put three of my merino wool sweaters into the wash. I took their measurements before washing as well as after washing.

Comparing these two numbers gave me the “Change in Size” metric. Like in the previous experiment, this metric helped me ascertain if my merino wool garments had shrunk or stretched.

Here are the results of this little experiment, tabulated for your convenience.

SweaterChange in Size
Uniqlo Merino Wool SweaterNo change in size
Icebreaker Merino Wool SweaterNo change in size
Howies Merino Wool SweaterSlightly shrunk
Results of washing merino wool

Now, the results of the experiment are very clear.

No matter how you wash your merino wool sweater, you can be certain that it is not going to stretch more than its current size.

Is Merino Wool A Stretchy Fabric?

One thing that you must be aware of is that up until this point, I was talking about permanent stretch here, the kind that leads to a loss of shape and structure.

But there’s another aspect to the relationship between merino wool and stretchiness.

If we’re talking about the stretchiness of merino wool as a fabric in terms of how much it can stretch to fit the body, then we can consider merino wool to be a very stretchy fabric.

It is due to this reason that merino wool is a great material for socks, as socks require fabrics that retain their stretch, wear after wear. If you want to know more about merino wool socks, you can check out this article here.

If you stretch a merino wool sweater by 20-25%, it still manages to bounce back to its original shape. That’s why I always recommend MagicOfClothes readers to downsize with merino wool sweaters.

If you are a Large, then try a Medium first. If you are a Medium, try the small.

You get the idea.

Final Remarks

I love merino wool. I think it is often overshadowed by cashmere and is not given proper credit.

You can even dye merino wool sweaters in your favorite color.

They have long been a staple in the winter closet of men and women, and now that you know that merino wool does not stretch and retains its size, you can add them to your wardrobe too!