Marker efficiency
The percentage of the fabric area covered by pattern pieces in a marker; the rest is waste.
A marker with 85% efficiency leaves 15% of the area as waste between the pieces. Efficiency depends on the shapes of the pieces, the sizes combined in the marker, the grainline restrictions and the fabric width, and it drives cost directly: higher efficiency means less fabric per garment. Computerized marker-making software tries many arrangements to improve it.
Example
If rearranging the pieces takes a marker from 82% to 85% efficiency, it saves about 3.5% of the fabric in the lay.