loft

In textiles, loft is the vertical thickness of a material measured under its own weight alone, with no external compression applied. Think of it as the height a fabric or fiber mass naturally assumes when laid flat and allowed to settle. For batting, insulation, or pile fabrics, loft directly affects both the feel and the performance of the finished goods. A thick loft feels plusher to the touch; a thin loft feels denser and more compact.

Loft matters most in three categories of textile production. First, in synthetic fiberfill and batting used for quilts, pillows, and outerwear, loft determines warmth retention and weight. A 2-inch loft batting will trap more air than a 1-inch loft batting, making it warmer but heavier. Second, in carpet and rug backing, loft affects durability and foot comfort. Higher pile loft creates a softer walking surface but may crush more readily under traffic. Third, in technical textiles like nonwovens and felts, loft controls drainage, filtration rate, and compressibility.

Measuring and Specifications

Loft is measured in inches or millimeters, typically using a dead-load compression testing machine. The material sits under a standard weight (often 1 pound per square inch or less) for a set time, usually one minute, then the vertical thickness is recorded. This differs from compressed loft, which is the thickness under actual use pressure, or recovery loft, which measures how quickly material bounces back after compression is removed. Fiber type, crimp, denier, and density all influence loft. Polyester fiberfill with high crimp yields greater loft than straight-filament fibers of the same weight. Down and feather have exceptional loft-to-weight ratios, which is why they remain the benchmark in premium insulation, though they are harder to manage in mass production.

One of the chief problems with loft is loss over time. Repeated compression, humidity, and mechanical agitation flatten fiber crimp and close air pockets, causing the material to compress and reduce its insulating or cushioning properties. This is called loft retention or loft loss, and it is a critical measure of product longevity. A pillow that loses 50 percent of its loft within two years will feel thin and unsupportive. Manufacturers test loft retention by compressing samples thousands of times and measuring remaining thickness.

The term "loft" comes from the Old Norse word for an upper room or attic space, and later referred to the height of a room. In textile use, it carries that sense of vertical airiness. The word entered textile vocabulary early in the twentieth century as manufactured fiberfill became common, and it has remained the standard term across North American mills and retailers. In European and Asian markets, the term thickness, bulk, or pile height may be used instead, though loft is increasingly international in technical trade documentation.