Sewing & fabric

Sewing and quilting math without local pricing: fabric yardage and area from bolt width, oz/yd² ↔ GSM weight conversion, cut sizes with seam allowance, uniform pattern scaling, and continuous bias tape yield from a fabric square. US and metric units throughout — charts vary by brand; use as planning estimates.

Yardage estimates assume you can lay pieces out efficiently, and several things break that assumption. Directional prints, one-way napped fabrics such as velvet or corduroy, and large repeats all force pieces to be cut the same way round, which can add a surprising amount to the requirement. Plaids and stripes need extra for matching across seams. Buy a little more than the calculation suggests: natural fibres shrink on their first wash, so pre-washing before cutting is worth the time, and dye lots differ enough that returning for more of the same bolt later rarely matches. Seam allowance conventions also vary by tradition — quilting typically uses a quarter inch, while garment patterns commonly use five-eighths — so check what your pattern assumes before adding it to a cut size.