I've used a fit calculator before and I'm still in between sizes. My height puts me in a larger bike, but my inseam, arm length and/or torso length put me into something different. Really, the best way to determine a bike size is to ride. But, as said above, you can always get a little longer stem to extend your reach on a frame that's a CM too small, versus not being able to shrink a bike that's too big (I once bought a 61cm based on a fit calculator and it was WAY too big for me).
Also, I prefer a slightly smaller bike, YMMV.