Measurement
Width is the distance across a slab, measured across the grain.
Natural edges make width variable. A useful listing shows where each reading was taken or provides a traced outline.
Plan from the narrow usable section instead of the widest point. Trimming defects and straightening edges can reduce it further.
More terms
Dimensions state the measured length, width and thickness of a piece.
Calibration compares a measuring tool with a known reference so its readings can be trusted within stated limits.
Thickness is the distance between the two broad faces of a board or slab.
Length is the longest dimension of a slab, measured along the grain.