Will 70% Cotton 30% Polyester Shrink? A Detailed Look

When buying fabric or clothing, the shrinking potential is an important factor to consider. You don’t want your favorite shirt or pair of jeans to suddenly not fit after the first wash. So if you’re looking at a 70% cotton 30% polyester blend, the big question is: will it shrink?

If you’re short on time, here’s a quick answer: Cotton shrinks, polyester doesn’t. So a 70/30 cotton/polyester blend will shrink some, but less than 100% cotton fabric. The polyester helps minimize overall shrinkage.

In this comprehensive article, we’ll look at how cotton and polyester differ when it comes to shrinkage. We’ll go over how the blend ratio impacts shrinkage, and provide care instructions to minimize shrinking for 70/30 fabric.

The Shrinkage Factors of Cotton and Polyester

Cotton Shrinks Due to Its Absorbency

Cotton is a natural fiber known for its absorbency and breathability. When cotton fabric is exposed to water, it tends to absorb the moisture, causing the fibers to swell. This swelling leads to shrinkage when the fabric is dried.

The amount of shrinkage can vary depending on several factors, including the type of cotton, the weave of the fabric, and the care instructions followed during washing and drying.

According to a study conducted by the Cotton Incorporated, cotton fabrics with a higher percentage of cotton, such as 100% cotton, have a higher tendency to shrink compared to fabrics with a blend of cotton and synthetic fibers like polyester.

A fabric made with a blend of 70% cotton and 30% polyester is likely to experience some degree of shrinkage, although it may not be as significant as 100% cotton fabric.

It is important to note that cotton shrinkage can be minimized by following proper care instructions. Washing cotton fabrics in cold water and avoiding high heat in the dryer can help reduce shrinkage.

Additionally, prewashing the fabric before sewing or using it for a project can also help mitigate shrinkage.

Polyester Does Not Shrink When Washed

Polyester, on the other hand, is a synthetic fiber that is known for its resistance to shrinking. Unlike cotton, polyester does not readily absorb water, which means it does not undergo the same swelling and shrinking process as cotton when exposed to moisture.

The Polyester Council of America states that polyester fabrics are highly resistant to shrinkage and will maintain their shape and size even after multiple washes. This makes polyester a popular choice for clothing and textiles that require minimal maintenance and longevity.

While polyester does not shrink, it is important to note that it can be susceptible to heat damage. High heat in the dryer or ironing at high temperatures can cause polyester to melt or warp. Therefore, it is recommended to follow the care instructions provided by the manufacturer to ensure the longevity of polyester garments.

How 30% Polyester Impacts 70% Cotton Shrinkage

When it comes to the shrinkage of a fabric blend, the percentage of each fiber plays a crucial role. In the case of a 70% cotton and 30% polyester blend, the presence of polyester fibers can significantly impact the shrinkage of the cotton fabric.

Polyester Fibers Help Minimize Shrinkage

Polyester fibers are known for their ability to resist shrinking. Unlike natural fibers like cotton, polyester does not have the same tendency to shrink when exposed to heat or moisture. This is because polyester is a synthetic fiber that is made through a chemical process, resulting in a more stable structure.

When blended with cotton, the polyester fibers act as a stabilizing agent, helping to minimize the shrinkage of the cotton fabric.

The presence of polyester in the blend creates a stronger and more durable fabric overall. This is particularly beneficial when it comes to maintaining the shape and size of the garment after washing. The polyester fibers help to counteract the natural tendency of cotton to shrink, resulting in a fabric blend that is less prone to significant shrinkage.

It is important to note that while the presence of polyester can help minimize shrinkage, it does not completely eliminate it. Cotton fibers still have the potential to shrink to some extent, especially when exposed to high heat or aggressive washing methods.

However, the addition of polyester in a 70% cotton and 30% polyester blend provides a level of stability that can help reduce shrinkage compared to a pure cotton fabric.

Pre-washing Can Further Reduce Shrinking

If you are concerned about the potential shrinkage of a 70% cotton and 30% polyester fabric blend, pre-washing can be an effective solution. Pre-washing involves washing the fabric before sewing or wearing it, allowing any initial shrinkage to occur.

This process helps to minimize the chances of significant shrinkage happening later on when the garment is washed.

By pre-washing the fabric, you give the cotton fibers an opportunity to shrink and stabilize before they are incorporated into a garment. This can help reduce the overall shrinkage and ensure a better fit and longevity of the garment.

When pre-washing a fabric blend, it is important to follow the care instructions provided by the manufacturer. This may involve using a gentle cycle, avoiding high heat settings, and using a mild detergent.

Taking these precautions can further reduce the potential for shrinkage and help maintain the integrity of the fabric blend.

Tips to Prevent a 70/30 Blend From Shrinking

When it comes to clothing made from a 70% cotton and 30% polyester blend, shrinkage can be a concern for many people. However, there are several measures you can take to minimize the risk of shrinkage and keep your garments looking great for longer.

Here are some helpful tips to prevent a 70/30 blend from shrinking:

Wash in Cold Water

One of the most effective ways to prevent shrinkage in a 70/30 blend is to wash the garment in cold water. Hot water can cause the fibers to contract and shrink, whereas cold water helps to maintain their original shape and size.

By using cold water, you can keep your clothing looking as good as new, without worrying about shrinkage.

Tumble Dry Low

Another important tip is to always tumble dry your 70/30 blend on a low heat setting. High heat can cause the polyester fibers to melt and the cotton fibers to shrink, resulting in a smaller and misshapen garment.

By opting for a low heat setting, you can protect your clothing from excessive heat and potential shrinkage. If possible, it’s even better to let your clothes air dry to avoid any heat-related shrinkage.

Use a Gentle Detergent

The detergent you use can also play a role in preventing shrinkage in a 70/30 blend. Opt for a gentle detergent that is specifically designed for delicate fabrics. Harsh chemicals in regular laundry detergents can weaken the fibers and make them more prone to shrinkage.

By using a gentle detergent, you can help preserve the integrity of the cotton and polyester blend and reduce the risk of shrinkage.

Remember, following these tips can significantly reduce the chances of your 70/30 blend garments shrinking. However, it’s important to note that some shrinkage may still occur, especially if the garment is not cared for properly.

Always read and follow the care instructions provided by the manufacturer to ensure the longevity of your clothing.


To conclude, a 70/30 cotton/polyester blend will shrink some, but less than pure cotton. The polyester fibers interspersed with the cotton act to stabilize the material and reduce shrinkage. Still, pre-washing fabric or garments before construction or first wear can help minimize shrinkage.

When laundering 70/30 blends, using cooler water, low dryer heat, and gentle detergents will also keep shrinking to a minimum so you can enjoy your cotton-polyester items over the long term.

Similar Posts