Fabric Calculator

Fabric is sold by length off a roll of fixed width, so the question is never "how many square yards" — it is "how many times does my piece fit across the width, and how long does each of those runs need to be".

That is why fabric width matters so much. A 60-inch-wide curtain panel fits in one width of 60-inch home-decor fabric but needs two widths of 44-inch quilting cotton, which doubles the yardage even though the finished curtain is identical.

Every project then adds its own allowances. Curtains need eight inches at the bottom for a doubled hem and four at the top for the header. Pillow covers need a seam allowance plus two overlapping back panels. Quilt backing needs four inches of overage on every side so it can be loaded on a frame. Those allowances are built in rather than left for you to remember.

1. Step 1 Usable width usable = fabric_width − 1 in Half an inch of selvedge each side is unusable.
2. Step 2 How many widths across widths = ceil(piece_width ÷ usable) Curtains: piece_width = window × fullness ÷ panels.
3. Step 3 Cut length per width cut = finished_length + allowances Curtains +12 in, skirts +4 in, quilt backing +8 in, tablecloths +2 in.
4. Step 4 Round up to the pattern repeat cut = ceil(cut ÷ repeat) × repeat Only if the fabric has a repeat. This is where patterned fabric gets expensive.
5. Step 5 Total, in yards yards = widths × cut ÷ 36, rounded up to the next ¼ yard

Example: a pair of curtains for a 48-inch window at 2× fullness needs 48 in of gathered width per panel. On 44-inch fabric that is two widths per panel, four widths total, each cut at 96 in. That is 384 inches, or 10.75 yards.

• One inch is deducted from the stated fabric width for selvedges. Some fabrics have wider unusable edges, particularly printed home-decor cottons.
• Curtain allowances are 8 inches for a doubled bottom hem and 4 inches for a rod-pocket or tape header, plus 2 inches total for side hems. Pinch-pleat or interlined curtains need more.
• Curtain fullness defaults to 2×, which is the standard for a gathered heading. Wave and eyelet headings often specify 2.2–2.5×; flat panels use 1.5×.
• Pillow covers assume an envelope back with two panels overlapping by about 40% of the pillow height, and a 0.5 inch seam allowance. Zipped covers need slightly less fabric but more hardware.
• Quilt backing includes 4 inches of overage on every side, which is what most longarm quilters ask for. If you are quilting it yourself on a domestic machine, 2 inches is usually enough.
• Pattern repeat is applied by rounding every cut length up to a whole repeat. This is what makes patterns match across seams, and on a large repeat it can add 20% or more to the total.
• Nothing here accounts for shrinkage. Cotton and linen lose 3–5% on the first wash, so pre-wash before cutting or buy extra.
• Directional prints and napped fabrics such as velvet must all be cut the same way up, which can prevent efficient nesting of pieces. The estimates here assume a non-directional fabric.