I am always cold.  I wear Cuddle Duds at work most days because my desk is freezing.  I needed something warmer to wear outside as a base layer.  I am usually a medium.  I bought a large because it was cheaper than the medium by a few dollars.  I should have bought the extra large.  The  shirt is nicely fitted and warm.  It fits easily under a second layer of clothing, but it is too short.  Did I accidentally order a petite size? I'm always tucking in the back.  i don't think I have ever been referred to as tall. I could put an undershirt under it, but that defeats the moisture wicking benefits. It is also a bit tight for that.  I need to trade with the reviewer who said she is usually an extra large but found the large to be a good fit.  Maybe there isn't any consistency in the manufacturing.  I still give it four stars because it is warm, and I don't feel sweaty in it. If I order again, I will look for an extra large tall, but I will probably swim in it!