We have all heard someone say the phrase 'I need a 1 X 6' before, but what does it actually mean?   What you just heard was a nominal lumber size.   This is what the pre-dried and cut rough lumber board is pre-sized to.   When you measure the board after processing, it will measure 3/4" X 5-1/2".   Here at Bossen Architectural Millwork, we will only refer to boards by their actual size, not by nominal.   If you want a 1 X 6, we will write you up a ticket that says 3/4" X 5-1/2" to avoid confusion.   Of course, if you want a board at a true 1" X 6", we can do that to.   This is why we do not refer boards by nominal sizes, only by actual, so everyone is clear about what they are getting.