In article , Mikey wrote:
I'm about to start making the upper cabinets of a kitchen project and
I was wondering if it would be a good idea to add a couple of extra
inches to the length of the cabinet and face frame to accommodate
under cabinet lighting? All suggestions welcome.
Mikey

The better undercabinet fluorescents are less than 1-1/4" vertically.

You don't have to add much.