If its cotton likely it will shrink, up more than in, usually. And the quality of the cotton plays a part in the drying, shrinking results. And a warm or hot water wash with a trip through the dryer shrinks a cotton shirt about one whole size.
Well, almost all cloths shrink in the dryer so in that case I hang mine on a line to dry (of course inside, don't want people stealing my clothes). I also shop at Forever 21 and I do sometimes use the dryer and when I put them in they shrink about a size smaller than what I bought. That's why I buy size bigger than I actually am. Hope that helped! :)