It really depends on your shoulder width and what you're wearing. If you have broad shoulders, a jacket or shirt may hang down loosely enough to easily conceal a firearm. I own several jackets which could easily conceal even a full-size 1911 in a belt clip holster.
Of course, there's 2 ways of looking at CCW, depending on your particular goals and your local laws: one is to carry a concealed firearm at virtually all times, without anyone knowing you have it; complete concealment. The other is to simply give you that legal right, and also cover your butt legally if you happen to wear a jacket or something else that conceals your firearm while otherwise open carrying. Depending on your goals and needs, you may not even care if the firearm is visible under certain circumstances, so long as it's concealed the vast majority of the time.
So basically, you need to decide what your goals are: do you NEED 100% concealment or absolutely no printing, or is it okay if people can tell "something" is there when you move a certain way (with the right holster and the right jacket, a cellphone pouch or a large wallet in your pocket will print more than the holster). Or is it even okay if someone sees the bottom of the holster if you raise your arms over your head? What level of concealment do you need? That should be the deciding factor.