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Do Cotton/Polyester Fabrics Shrink? Here’s What You Need To Know

Cotton and polyester blends combine the advantages of each fiber while minimizing the disadvantages. One of the drawbacks of popular cotton material is how much it shrinks in the wash – so, do cotton/polyester fabrics shrink? Let’s explore the impact of shrinkage on poly/cotton clothing.

Many people know that cotton is prone to shrinking when you wash (and dry) it while polyester doesn’t really shrink. Have you ever wondered if your cotton/polyester blend clothing will shrink after washing? 

The answer is yes, it is possible for cotton/polyester fabrics to shrink, but there’s a caveat. The amount of shrinkage will vary depending on a couple of important factors: the specific fabric blend and how you wash and dry the fabric.

a guide on cotton/polyester shrinkage

The Shrinking Phenomenon

Shrinkage can be a big issue and it can literally destroy a garment. Look at the image below. The pink pullover and the green one are the same size. Or should I say were, because the green one was washed (by mistake) in hot water and this is the result. I have to mention though that this is made out of 100% cashmere, not cotton. But while the cotton shrinkage may not be that dramatic as that of wool, it’s still might be significant.

shrinkage of my cardigan after washing

Cotton, as a natural fiber, is known to shrink when exposed to moisture and heat. It’s one of the most common natural fibers used in clothing due to its breathability, durability, and comfort. However, cotton can shrink quite a lot when washed in hot water or dried on a hot setting in the dryer. 

On the other hand, polyester is a synthetic fiber that’s used in clothing because of its quick-drying and wrinkle-resistant properties and silky feel. As a synthetic fiber, it’s more resistant to shrinking. Polyester is nevertheless a thermoplastic fiber, meaning that at a certain temperature it softens and then becomes pliable, then solidifies again upon cooling.

Increasingly, manufacturers rely on various poly-cotton fabric blends to take advantage of the appealing properties (and minimize the drawbacks) of each material.

If you want to learn more about these blends, check out my Cotton Polyester Blends 101 post.

One of the properties manufacturers want to minimize is the degree of shrinkage a fabric will experience. 

When cotton and polyester are blended together to create a cotton/polyester fabric, the resulting fabric may still shrink some, but it will be less than what you will see cotton alone do. 

Research on Poly/Cotton Blends Shrinkage

Have you wondered why most t-shirts or other garments that are made out of a polyester/cotton blend are 40/60 polyester/cotton? I did. After all, why not 80/20, or 50/50? The answer is surprising!

60 cotton 40 polyester fabric

I found the following article in a specialized publication Effect of blend ratio on the properties of Polyester/Cotton fabric (academia.edu) and they present very interesting data regarding this subject. The following is an excerpt, the full article is at the link above.

A sample of 10cm was marked out of each selected fabric. The samples were then immersed in boiling water for 2 hours.The specimen was carefully removed and laid on a flat surface and allowed to dry naturally at room temperature. After drying, the dimensions were re-measured and the percentage shrinkage was calculated using the formula:

formula to calculate shrinkage

The percentage shrinkage of a fabric is an indication of its dimensional stability [3]. The result from Figure 12 shows that after treating the blended fabrics in boiling water for 2 hours, polyester was found to have 0% shrinking in the weft direction. This is a feature of a thermoplastic fibre. Cotton (100%) has the highest shrinkage. This proves that in other samples, the polyester composition has contributed to their dimensional stability since shrinkage increases with decrease in percentage composition of polyester in the samples.

research results on fabric shrinkage

In all the Figures, 1 = 100% polyester, 2 = 80/20 polyester/cotton, 3 = 65/35 polyester/cotton, 4 = 40/60 polyester/cotton and 5 = 100% cotton.

From this research it is obvious that the blends affected the least by shrinkage are the 80/20 and 40/60 blends. All others seem to cause a distortion (different shrinkage weft / warp) in the shape of the garment since they will shrink at different rates. Who knew?

Please note that the researchers used boiling water which is not necessarily something you will use when washing your garments, so the shrinkage in the graph should be taken probably as a maximum shrinkage.

This research into the shrinkage properties of cotton/polyester blend fabrics suggests that these materials tend to shrink less than 100% cotton fabrics. 

When discussing fabric shrinkage, particularly in woven fabrics like those made from a poly/cotton blend, it’s important to understand the concepts of warp and weft. These terms refer to the orientation of the threads that make up the fabric.

Warp threads run lengthwise on a loom and are held taut during the weaving process. Weft threads, on the other hand, are interlaced with the warp threads, running crosswise from side to side. Due to the tension placed on the warp threads during weaving, they often have a tendency to shrink more upon washing compared to the weft threads, which are not under the same tension.

This difference in shrinkage between the warp and weft directions can affect the overall dimensional stability of the fabric. Given that warp and weft threads can shrink differently, manufacturers and textile scientists often design the fabric structure and finishing processes to minimize these differences, aiming for a uniform shrinkage that maintains the fabric’s shape and size after laundering.

Cotton And Polyester Properties

What shrinks more cotton or polyester?

Since one is a natural fiber and the other is synthetic, it makes sense that cotton and polyester behave differently. 

Cotton is known for noticeably shrinking when exposed to high heat.

✅ Related article: Quilting Cotton: The Essential Fabric for Quilters

Polyester, on the other hand, does not shrink nearly as much as cotton does (but it’s important to know that it CAN shrink some). 

When you blend these two fabrics, the resulting material can still shrink, but the degree of shrinkage depends on the specific blend of cotton and polyester used. 

Specific Poly/Cotton Fabric Types And Their Behaviors

There are various types of cotton/polyester fabrics, and you can expect each one to behave differently as it relates to shrinkage. 

Here are some of the most common types of cotton/polyester fabrics and how they tend to behave:

  • 80/20: Predominantly cotton, this blend is soft and breathable. However, expect it to shrink and noticeably lose its shape with repeated washing and drying.
  • 65/35: Also mostly cotton, this is a popular and affordable blend for clothing that offers an appealing mix of softness, breathability, and resistance to wrinkling and shrinking. 
  • 60/40: Also known as CVC (Chief Value Cotton), this blend maximizes affordability and appealing qualities. Most used blend.
  • 50/50: This equal balance of both fibers creates a popular material for activewear with some shrinkage. However activewear usually has some spandex in it so shrinkage might not be essential.

Does 60 cotton 40 polyester shrink?

Short answer: yes, it can shrink. The good news is that it will shrink the same way both ways (warp/weft) and will not distort the shape of the item.

How much does 60 cotton 40 polyester shrink? It ranges from about 1%-5%. The amount of shrinkage will depend on how you care for the fabric.

To minimize shrinkage in a 60 cotton 40 polyester fabric, I recommend following the instructions found on the care label. Generally, those labels will recommend washing the fabric in cold water and tumble drying it on low heat (or hanging to dry).

care label of my pajama

Keep in mind that using hot water or high heat settings on the dryer will cause the maximum amount of shrinkage.

Some cotton/polyester blends may be pre-shrunk, so check the care label to see if this is the case. If so, you may be able to wash and dry your garment as normal without worrying about shrinkage.

Fabric Manufacturers Can Control Shrinkage in Poly/Cotton Blends

Manufacturers employ several techniques to control shrinkage in poly/cotton blend fabrics, so that the final product maintains its size and shape after washing. Here are some of the methods they use:

One of the most common methods to control shrinkage is pre-shrinking the fabric before it is cut and sewn into garments. This can be done through a process, where the fabric is moistened and then mechanically compacted to reduce its potential to shrink after the consumer washes it.

For synthetic fibers like polyester, heat setting is an effective method to stabilize the fabric. The fabric is exposed to a high temperature that sets the fibers’ shape, reducing the chance of shrinkage because polyester has a “memory” for its heat-set shape.

Manufacturers can adjust the ratio of cotton to polyester to control shrinkage. Higher polyester content generally means less shrinkage due to the synthetic fiber’s resistance to water absorption and its dimensional stability.

The way the fabric is woven can also impact shrinkage. A tighter weave can help to reduce the space into which the fibers can contract, thus minimizing shrinkage.

Applying chemical finishes to the fabric can also help to reduce shrinkage. These finishes can coat the fibers, making them less prone to absorbing water and swelling, which is a common cause of shrinkage in natural fibers like cotton.

Controlling the tension and temperature during the drying process after washing can help minimize shrinkage. Tensionless drying methods can allow the fabric to relax and reduce the chances of shrinkage.

Some manufacturers use cross-linking agents that chemically bind with the cellulose in cotton. These agents can help to prevent the fibers from swelling and shrinking.

The structure of the fabric, including yarn twist, density of weave, and the balance between warp and weft yarns, is designed to minimize differential shrinkage between these two directions.

By carefully considering the fabric’s end use and employing a combination of these techniques, manufacturers can effectively control shrinkage in poly/cotton blend fabrics.

Understanding the Impact of Fabric Shrinkage on Your Garments

When a garment is said to have a shrinkage rate of 5%, it means that the fabric can potentially reduce in size by 5% after washing. For an adult-sized garment, this can be quite noticeable, depending on the original fit.

Let’s say you have a shirt that originally measures 40 inches around the chest. A 5% shrinkage rate would mean that the shirt could potentially shrink by 2 inches in that area, making the chest measurement 38 inches post-shrinkage.

poly/cotton shirt shrank after washing

Whether the shirt can still be worn by the same person depends on how snug the shirt was before shrinking. If the shirt was already a close fit, losing those 2 inches might make it too tight to wear comfortably. However, if the shirt was a loose fit to begin with, it might still be wearable, just a bit more fitted.

In terms of appearance, 5% shrinkage can be quite visible to the eye, especially in length. For pants or sleeves, a 5% reduction can make a noticeable difference in how the garment sits on the body. For example, sleeves and pant legs can appear unexpectedly shorter, which might not be the desired look or feel.

jeans that became too short after washing

Shrinkage doesn’t always occur uniformly. Some parts of the garment may shrink more than others, potentially leading to a distorted shape, which can affect the overall fit and appearance.

Shrinking Effects Of Washing And Drying

To minimize shrinkage when washing and drying and help cotton/polyester fabrics maintain their shape, it’s important to be vigilant about caring for them properly. Machine washing and tumble drying can be convenient, but they can also cause damage to cotton/polyester fabrics. 

fabric in a washing machine

To avoid damage, employ these tips:

  • Washing: Use cold or warm water and a gentle detergent. Avoid using hot water, as this can cause shrinkage and combined with the machine movement can cause the polyester fibers to change their shape. Alternatively, you can also hand wash items in cold water. Soaking your clothes before washing can also help to remove dirt and stains without causing damage.
  • Drying: What is the role of drying? Avoid using high heat and overdrying the materials, because that can cause damage and shrinkage. Instead, use a low or medium heat setting and remove items as soon as they’re dry. Alternatively, you can air dry your clothes by laying them flat on a towel or hanging them up to dry.

Pro Tip: If you’re unsure about the best way to care for your clothes, check the care label for specific instructions.

Shrinkage of Garments with Zippers

Special care must be taken when washing poly/cotton blend (especially with high cotton content) garments with zippers. Modern zippers are mostly polyester. Cotton shrinks at a significantly higher rate than polyester so when washing such a garment you may have unwanted results like in the images below.

The hoodie below is 70% cotton / 30% polyester so it will shrink between 3 and 4% when washed in hot water. The zipper is 100% polyester and will shrink probably around 1% or  even less. The length of the zipper is about 20” (50cm) and the difference in shrinkage between the hoodie and the zipper is very significant, about ¾” (1.5cm). You can see the result in the second image, the zipper is now longer and distorts the shape of the hoodie.

70 cotton 30 polyester my hoodie
my hoodie shrank differently than the zipper of the hoodie

The good thing is that this particular problem (zippers shrinking at a different rate) can be fixed sometimes (especially if the fabric is stretchy knit), depending on fabric and my short video below shows one way of doing it.

How To Shrink A Cotton-Polyester Blend The Right Way

Most of the time, people want to avoid shrinking their garments. However, as a sewist, there are times when we WANT to shrink our fabric (before cutting and sewing) so that it will maintain a better shape once the garment is complete.

If you want to intentionally shrink your cotton/polyester blend garment (or fabric), you can try washing it in hot water and drying it on high heat. You can even do this more than once to further reduce any shrinkage after the project is complete. 

Note: You can use this method when you want to shrink 80 cotton 20 polyester or shrink 50 cotton 50 polyester – and everything in between!

The amount of shrinkage you get will depend on the specific blend you’re using.

Top Cotton/Polyester Blend Clothing Care Techniques

Here are some general care tips to help you keep your cotton/polyester blend clothing looking great. I know, I am repeating myself, but it only takes one mistake to ruin a garment, and probably all of us have made that mistake many times. I know I did!

  • Wash in cold water: Always use cold water because hot water can cause the cotton fibers to shrink, which can make your clothing look misshapen.
  • Use gentle detergent: Harsh detergents can damage the fibers and cause your clothing to lose its shape. For best results, use a gentle option instead.
  • Avoid high heat settings: Drying clothing in high heat and overdrying fabrics can cause the cotton fibers to shrink, which can lead to your clothing becoming misshapen. Instead, use a low heat setting or hang dry your clothing.
  • Shape your clothing: If you air dry your clothing, it can still run the risk of becoming misshapen. I recommend reshaping it while it is still damp to help it dry correctly and keep its original shape.

Frequently Asked Questions

What is the shrinkage percentage for 80/20 cotton/polyester fabric?

The percentage for 80/20 cotton/polyester fabric will vary depending on the care instructions and the specific fabric. However, on average, you can expect this blend to shrink up to 5% in the wash.

How much does 65% polyester and 35% cotton shrink?

While the amount of shrinkage for 65% polyester and 35% cotton fabric can vary, keep in mind that this blend is less likely to shrink than a blend containing more cotton. As a rough estimate, this blend may shrink around 1-2% in the wash. It is also likely that the material will shrink at different rates in different directions.

Will 55% cotton and 45% polyester fabric shrink?

Yes, 55% cotton and 45% polyester fabric can shrink, although it won’t shrink as much as a fabric with a higher percentage of cotton. On average, it may shrink around 3% – 4% in the wash.

What is the best way to shrink 50/50 cotton/polyester fabric?

The best way to shrink 50/50 cotton/polyester fabric is to wash it in hot water and dry it on high heat. Once it’s dry, take it out of the dryer and inspect it thoroughly because this method could damage some materials. Beware if the material has spandex in it (even a small amount), hot water can destroy the elasticity.

Another option is to boil the fabric for a few minutes in a big pot of clean water on the stove or let it soak in hot water, then dry in high heat. I personally prefer the machine washing and drying method.

Pro Tip: If the material is dyed, the colors are more likely to run in hot water. You can add a teaspoon of white vinegar to the machine or the pot to help prevent the colors from running.

Will 70 cotton 30 polyester shrink?

Yes. Similar to 75/25 and 80/20 blends, you can expect this fabric to shrink but still less than 100% cotton would. Don’t be surprised to see a shrinkage percentage of around 5% (give or take based on water and drying temperatures).

Can 75% cotton and 25% polyester fabric shrink?

Yes, 75% cotton and 25% polyester fabric can shrink, but again, not as much as a fabric with a higher percentage of cotton. On average, it may shrink up to 5% in the wash.

If you’ve ever pondered the question “do cotton/polyester fabrics shrink?” I hope this post answers it for you! Whether you’re trying to shrink your material as a sewist or prevent it from shrinking so it keeps its shape when wearing, follow these general guidelines to keep your garments looking their best for years to come. 

If you ever have questions about caring for your particular fabric, check the care label for more information.

Was this guide useful to you? Don’t forget to save this pin (see below) to your sewing board for future reference on cotton/poly blend fabric shrinkage. Plus, follow me on Pinterest to stay updated with more handy tips, step-by-step tutorials, and creative inspiration!

a guide on cotton/poly blends shrinkage

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Saturday 2nd of December 2023

Thank you so much-I really appreciate the how and why.

Sherri Maher

Saturday 2nd of December 2023

Another very interesting and helpful article Olga. Thank you for all the great info you share with us!

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