What Does 4 4 Mean

4/4 ("four-quarter") means 1" of rough thickness before any surfacing — the baseline the entire quarter system is built from, and the thickness most hardwood lumber gets bought and sold at by default.

Why this one specifically

Every other quarter designation on this site is described relative to 4/4, because it's the size a lumberyard defaults to when nobody specifies otherwise, and the size most hardwood boards arrive at from the sawmill unless a project specifically calls for something thicker. After surfacing two sides (S2S), a 4/4 board finishes around 13/16" — not a full inch — which is the same surfacing-loss story that makes a nominal 2x4 finish at 1.5" instead of 2": every pass through a planer or jointer removes real material, and 4/4 stock typically loses roughly 3/16" total across both faces getting flattened and cleaned up.

What moves the number

The 4/4 figure itself doesn't move — it's a fixed grading convention, not a measurement that varies by species or supplier. What does vary is how much of that inch survives to the finished piece: a board planed extra times to remove twist or cupping loses more thickness than one that started flat.