Guides / 01—08
Finished size versus cut size
Similar-looking measurements can produce different finished objects. Start with the result you want, then allow for joins.
Describe the finished object
Finished size means the width and length after edges are sewn or folded. Write these dimensions before drafting a pattern. For a rectangular panel, record width and length separately and mark which edge will be the top. A small sketch with fabric direction prevents swapped dimensions.
Add allowance at sewn edges
Seam allowance is the distance from the cut edge to the stitching line. If all four edges use the same allowance, cut width equals finished width plus twice the allowance; cut length follows the same rule. A folded hem, zipper or special join needs its own edge-by-edge calculation rather than this simple formula.
Record numbers before cutting
Put finished size, allowance at each edge and cut size on the pattern. Check with one ruler and one unit system. A commercial pattern may already include allowances; adding them again changes the finished size. Sew a small sample when fit matters.