Seam Allowance & Notches
How seam allowance, notches, and darts work in Niche Studio's pattern tools, with typical allowance widths by seam type.
What seam allowance is
Seam allowance is the margin added outside the stitch line so two pattern pieces can actually be joined. The pattern editor adds it as an offset around the cut edge, independent of the stitch line shown for construction reference, so you can change allowance width without redrawing the piece.
| Seam type | Typical allowance |
|---|---|
| Standard flat seam (side seam, shoulder) | 1.0–1.5 cm |
| Enclosed seam (collar, cuff, waistband) | 0.6–1.0 cm |
| Overlock/serged seam | 1.0 cm |
| Hem allowance | 2.0–4.0 cm depending on garment |
Notches
Notches are small marks cut into the seam allowance at points that must align during sewing — the front and back of a sleeve cap, the center back of a collar, or the start and end of a dart. Seam walking places notches automatically once two adjoining seam lines are matched for length.
Darts
A dart removes excess fabric to shape a flat piece around a curved body point (bust, waist, shoulder blade). In the pattern editor, darts can be rotated to a different location on the same piece, split into two smaller darts, or converted into gathers or a princess seam — each producing a different look from the same amount of shaping.