Rough-Sawn vs. Actual Lumber Dimensions
A board can have a rough dimension, a nominal retail size and a finished dimension. Confusing those terms can make a project fit badly or cause you to underestimate how much material you need.
Rough lumber
Rough stock has a textured surface and often has more thickness and width available for milling. A board sold as rough 4/4 is commonly intended to be milled down to a smaller finished thickness, although the exact result depends on the starting stock and how much material must be removed.
Surfaced lumber
Surfacing removes material to create smoother, more consistent faces and edges. The finished dimensions are therefore smaller than the rough dimensions.
Why the distinction matters
If a project requires an exact ¾-inch panel, buying ¾-inch finished material is a different proposition from buying rough stock and milling it yourself. You also need enough extra thickness to flatten, joint and plane the board without finishing below your target size.
Best practice
Ask the supplier whether the quoted dimensions are nominal, rough or surfaced. When precision matters, measure the actual stock before cutting. Then use those dimensions in your calculations.
Related tool
Use the Board Feet Calculator to estimate volume and cost from the dimensions you expect to buy. For common nominal sizes, see the common lumber sizes guide.