A bolt is a unit of cloth commonly equivalent to about 40 yards. It describes a packaged length of fabric, usually wound around a cardboard tube or folded for storage and sale.
The exact length of a bolt is not universal. Many textiles are sold in 40-yard bolts, but the amount can vary with the material, manufacturer, and trade. Canvas, for example, has traditionally been associated with a 39-yard bolt in some contexts. Width also varies, with common fabric widths ranging from about 35 inches to 60 inches or more.
A bolt is different from a yard, which measures a single linear yard of fabric, and from a bale, which generally refers to a compressed bundle of textile fibers or other goods. Retail fabric is often sold by the yard, while manufacturers, wholesalers, theatrical costumers, and interior designers may purchase full bolts. Because bolt lengths vary, professionals check both the bolt length and the fabric width before calculating how much material is available.