The three measurements are not interchangeable
- Finished size
- The visible size after a piece is sewn into the quilt.
- Unfinished size
- The size of a sewn unit before it is joined on all remaining edges.
- Cut size
- The dimensions used to cut the fabric before sewing.
For a basic rectangle, cut size equals finished size plus seam allowance on both opposite edges. With a ¼-inch seam, add ½ inch to both the finished width and finished height. A rectangle intended to finish at 3 × 6 inches is therefore cut at 3½ × 6½ inches.
Avoid adding seam allowance twice
Patterns usually say whether a measurement is finished or a cutting instruction. If the pattern says “cut 3½ × 6½,” enter it as a cut size; those dimensions already contain the allowance. If a design sketch says the piece should finish at 3 × 6, enter the finished dimensions and let the calculator add the selected seam allowance.
Half-square triangles need their method-specific starting-square formula, so use the HST calculator instead of treating them as plain rectangles.
Check the assumption before cutting
QuiltClarity defaults to a ¼-inch seam, but the field remains editable. Confirm the pattern, test your machine’s seam, and keep all inputs in one measurement system. Then use the fabric yardage calculator for a repeated piece or review the seam allowance guide for the full width-to-finished-size relationship.