Is it cheaper to reface cabinets or replace them?

Refacing runs roughly half the cost of replacement and takes days rather than weeks, so it wins whenever the existing boxes are sound and the layout already works. It replaces doors, drawer fronts and the visible face frame, and leaves the carcasses in place. It is the wrong choice if the boxes are particleboard that has swollen at the base, if any run is out of square, or if you want to change the layout at all, because none of those are problems a new door fixes.