Read WOF, then check the edges
Patterns often use WOF for “width of fabric,” meaning a cut across the fabric from one selvage to the other. The width printed on a bolt label may include those edges. Your usable width is what remains after trimming.
For example, 44 inch fabric with 1 inch removed at each selvage leaves 44 − 1 − 1 = 42 inches. That supports seven 6 inch cuts across the width, assuming no gaps or further trimming: 42 ÷ 6 = 7.
Width and length are separate
Buying more yardage adds length along the bolt. It does not make the fabric wider. Measure the usable width after any washing and trimming you plan to do, and keep the required grainline in mind when laying out pieces.