Why Do Baseball Players Wear Polyester Instead of Cotton?

Michael Claunch

The last 20 years have seen sportswear manufacturers such as Nike, Adidas, and Under Armour design creative, high-tech garments to keep athletes cool during the heat of play. 

Sweat-wicking, quick-dry materials that keep athletes cool or warm, depending on the weather, have become the norm in sports such as football, soccer, ice hockey, and basketball. Yet, baseball jersey material is a little different and seems to be behind the times compared to those other sports – or is it?

Although there are some reasons for baseball uniforms to be made from cotton rather than polyester, the current jersey material offers plenty of upsides. It isn’t just tradition that keeps polyester as the king of materials when it comes to baseball uniforms. 

So, why do baseball players wear polyester instead of cotton?

Why are baseball uniforms polyester?

In 1882, the National League officially declared teams must wear matching uniforms. Before 1882, teams often wore mismatched uniforms, and oftentimes, it was only the teams’ socks or stockings that matched. Teams were denoted by their sock color, hence the reason for the Cincinnati Reds, Chicago White Sox, and Boston Red Sox.

While the National League didn’t make uniforms mandatory until 1882, baseball can trace the uniform’s history back to 1849 when the New York Knickerbockers Baseball Club became the first team to wear them. 

Those early uniforms were a far cry from what players wear today. The Knickerbockers took the diamond, wearing straw hats, wool pants, and flannel shirts. Of course, it was the mid-1800s, but over the next few decades, little changed in much of the jersey material that players wore. 

It wasn’t until the 1970s that Major League Baseball teams began wearing double-knit polyester uniforms. Up to that point, players sometimes still wore flannel uniforms, which were extremely hot during the summertime. Polyester gave players a break from the sweat-inducing pants and jerseys.

In the lead-up to the 1970 Major League Baseball season, many teams wore uniforms solely made from flannel, while socks were designed with cotton material. Starting with the opening day of 1970, Major League Baseball teams slowly transitioned over to all-polyester uniforms. By the start of the 1973 season, the 24 teams that made up big-league baseball all wore double-knit polyester duds. 

It is remarkable to think just how far baseball has come over the years, and it is clear to see why baseball uniforms aren’t cotton. Just a half-century ago, baseball clubs in Major League Baseball had the option to choose between flannel or polyester uniforms. In modern baseball, teams are told what to wear by Major League Baseball and its uniform manufacturer. 

What are baseball uniforms made of?

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Modern baseball uniforms are still made of double-knit polyester. The material has some advantages, and these advantages are the key factors keeping polyester around. 

Baseball isn’t the only sport that uses polyester for its uniforms. Other sports around the globe use polyester or polyester blend for their uniforms.

Perhaps the most important factor in keeping polyester as the key baseball jersey material is its durability. The durability of flannel isn’t as strong, and the uniforms could potentially rip, tear, or fray during a season.

The rigors of baseball could cause tears and holes in pants and shirts. Moreover, regularly washing the uniforms may not only shrink them but take the color out of the jerseys and pants. 

Although polyester can feel heavy, it is oftentimes known as a lightweight material. Having a lightweight material is paramount for players competing in baseball and other sports.

The extra weight provided by some clothing materials can cause a baseball player to be weighed down. Even just a few grams could slow a baserunner down or restrict a batter’s swing. 

Why are baseball uniforms polyester and not cotton?

So, why aren’t baseball uniforms cotton instead of polyester? Well, there are a few more reasons baseball jersey material is polyester other than its durability. 

Cotton can restrict the airflow between the body and the uniform. Unlike polyester, cotton can be too tight to the skin. It can also stick to the skin if a player is sweaty or wet. 

The airflow provided by polyester allows a baseball player’s body to stay cool. This is important during summer baseball games when temperatures can reach above 100 degrees Fahrenheit. 

Another reason that baseball uniforms are not cotton is due to the ability to absorb moisture. The days of athletes wearing cotton t-shirts to train or play games are nearly over. Modern technology allows for sportswear material to provide comfort regardless of the weather. 

Polyester does not absorb moisture, which prevents a baseball jersey or pants from becoming heavier. Cotton simply sucks up moisture like a paper towel. 

In addition, the insulating properties provided by polyester keep players cool in summer and warm during the cooler months of the Major League Baseball campaign. 

So, why aren’t baseball uniforms cotton? There are plenty of great reasons, but perhaps the best is cotton has a tendency to shrink up after numerous washes. If taken care of properly, a polyester uniform won’t draw up in the wash or dryer. 


Major League Baseball uniforms have to be durable and stand up to the rigors of a 162-game regular season. Although each player’s uniform looks brand new for every game, teams do not provide fresh uniforms for each game. 

Players will be designated a set number of uniforms, and these will be their kit for the season unless a new jersey, hat, pair of pants, or socks are needed. If teams provided new uniforms with each game, the costs would be through the roof. 

Due to the durability of double-knit polyester uniforms, players can wear the same jerseys and pants throughout a full regular season. But polyester’s durability isn’t the only reason it is the preferred baseball jersey material.

So, why do baseball players wear polyester instead of cotton? Well, unlike cotton, polyester provides airflow allowing the body to stay cool. The material doesn’t absorb moisture. Rather it dries, keeping uniforms from becoming heavy on a player’s body. 

While there have been plenty of technological advancements in sportswear over the last two decades, baseball’s polyester revolution began in 1970, and it doesn’t seem to be ending anytime soon.

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