Construction term
The distance between the line of stitching and the cut edge of the fabric.
Garment patterns often use 5/8 inch or 1.5 cm; quilting commonly uses 1/4 inch. Always read the instructions.
A small error repeated across several seams changes the final dimensions of a garment or quilt block.
Allowances may be clipped on curves, graded in bulky seams, trimmed inside enclosed finishes, or left wide for fitting.
Useful distinction
They are not the same line. Confusing them is an impressively efficient way to resize a project unintentionally.
Practical guide
The correct width depends on what happens after the seam is sewn. Accuracy matters, but so do the room needed for fitting, clipping, grading, pressing, and the selected edge finish.
Garment patterns commonly use a wider allowance that supports fitting and conventional finishes. Patchwork uses a narrow quarter inch so units press flat without excess bulk. Bags, upholstery, and home projects may specify other widths based on material thickness and seam construction. The pattern instruction always outranks habit.
The stitching line controls the shape, not the raw edge. On an inward curve, clip the allowance toward the seam without cutting the stitches. On an outward curve, notch or grade excess bulk. At a corner, trim diagonally only after confirming the seam is secure.
Choose one reference point and keep the cut edge against it without forcing the fabric sideways. For a custom width, use removable tape or an adjustable seam guide. When the needle position changes, measure again from the active needle rather than relying on a familiar plate number.
French seams, flat-felled seams, bound seams, and facings consume or reorganize the allowance differently. A French seam needs enough width for two stitching passes; a flat-felled seam needs one layer wide enough to wrap the trimmed layer. Plan the finish before cutting.
Avoidable mistakes
Common questions
Usually, but not always. Check the pattern notes for the exact convention.
Watch the fabric edge at the guide and pivot in tiny increments with the needle down.
Narrow widths reduce bulk; wider ones support fitting, strength, or special finishes.
It is defined before pressing, from stitch line to raw edge.
