Figuring a Drop Pattern
In a typical pattern repeat, the design on one selvage is completed directly across from it on the opposite selvage. Occasionally, you will find a fabric with a drop pattern match (also called a half match or half-drop match) where the remainder of the design is, instead, moved up or down along the opposite selvage at an amount equal to one-half of the pattern repeat (see the illustration, below).

To calculate the allowance for matching a drop pattern, follow the first three steps in "Figuring Pattern Repeats" on the previous page. Then, add or subtract one-half of a repeat. Using the same 96-inch-long example, add or subtract 13-1⁄2inches (half of the 27-inch repeat) to/from 108 inches to determine a new cut length of 121-1⁄2 inches or 94-1⁄2inches. Since 96 inches was originally needed to make the treatment, subtracting one-half of a repeat would make the cut too short. In this case, add one-half of the repeat to allow 121-1⁄2 inches for each cut (in this example, 25-1⁄2 inches beyond the 96-inch length is waste). If the original amount of fabric needed had been less than 94-1⁄2 inches, you would have had to subtract one-half of a repeat.