The tallest pile tier in one dealer's four-tier scheme, about 1/2 to 5/8 in (12.7 to 15.9 mm) measured from the back of the rug to the top of the pile. It feels cushioned and cozy underfoot and usually comes with larger, bolder patterns, because rugs of lower knot density need no close trimming to look sharp. Together with medium pile it is recommended for busy living rooms, hallways, entryways and heavy furniture, but it needs more clearance under doors and takes longer to dry in damp rooms. Heriz, Mashhad, Sarouk, Bijar, Zanjan and Gabbeh rugs typically have it.
The flattening of pile fibers under sustained weight, as in a high-traffic path or beneath heavy furniture, which leaves the pile looking worn. In storage the same happens when heavy items are stacked on a rug for long periods. A rug pad and padded coasters under furniture legs spread the load, and rotating the rug about once a year shifts where the weight falls; a medium to high pile and a dense weave withstand heavy beds and dining tables best, and regular vacuuming and professional cleaning keep the pile in shape.
The height of a rug's knotted pile, measured from the back of the rug to the top of the pile with a ruler or caliper, so the foundation is included. One dealer scheme sorts it into low (1/8 to 1/4 in, or 3.2 to 6.4 mm), low-medium (1/4 to 1/3 in, or 6.4 to 8.5 mm), medium (1/3 to 3/8 in, or 8.5 to 9.5 mm) and high (1/2 to 5/8 in, or 12.7 to 15.9 mm). The final trim sets it: sharply detailed, densely knotted rugs, including silk and silk-and-wool pieces, are cut low, while coarse ones with large designs, such as Heriz and Gabbeh, keep a taller pile. A higher pile feels more cushioned, and a medium-to-high pile suits busy areas and heavy furniture; a lower pile clears doors, absorbs less humidity, traps less dust and vacuums more easily.