There was a time about 15 years ago when polo shirts and t-shirts were made mostly of cotton. And at that time, it was fairly common practice for people to expect cotton shirts to shrink as much as one complete size after a couple of washings.
Today, there are new fabrics and treatments to reduce the effect of “shrinkage”. One of those solutions, polyester, was still considered “plastic” and not a very comfortable fabric fiber. In addition, the technology did not exist to “preshrink” the cotton fibers to reduce the effect of shrinking after the manufacturing of the end fabric product.
My, how things have changed.
Today, nearly all of the major golf shirt manufacturers preshrink or treat their cotton fabrics to reduce the effect of shrinkage. A “preshrunk” shirt made of 100% cotton may still shrink a little. But now the amount of shrinkage is 2% to 4% vs. the old 5% to 10% of the past.
There is no more guessing about that size to get after trying to figure out how much a shirt was going to shrink.
Now the exception to this is t-shirts. Cotton t-shirts, because they are still a commodity affected by price, are generally not “preshrunk”. The market has decided that the added cost of treating the fabric is not worth the benefit of the preshrunk fabric. Therefore it is important to remember then when ordering t-shirts.
For example, I normally wear an XL golf shirt. In fact, nearly all shirts I get are XL. But when it comes to t-shirts, I order a 2XL. I like my t-shirts loose fitting and after they shrink a little, the 2XL fits just how I like it.
The bottom line is this. Order what you normally would pull off the rank in a retail store. If you are a “tweener” (sometimes an L and sometimes an XL), get the bigger size. You will wear it if it is too big, but not if it is too small.
But you don’t have to worry about shrinkage when you get a golf or button-down shirt.