I'm 5'8" with an athletic build and usually wear a medium, but the medium on this top runs a little big in places. That extra room could work for layering, but this top is warm enough that you probably won't want much under it. For a layer like this, I'd size down to a small.
I wear it for trail runs and easy after-work runs, and for cycling on crisp fall and early winter mornings/evenings…

























