ppi

Picks per inch measures the number of weft (crosswise) yarns woven into one linear inch of fabric. It is the vertical density of a woven cloth, complementary to ends per inch (epi), which counts warp yarns. Together, ppi and epi determine how tightly a fabric is constructed and how it will perform in use.

A fabric with 20 ppi will have twenty distinct rows of weft yarn in every inch of length. Fabric density directly affects weight, drape, stiffness, and tear strength. Densely woven cloth with high ppi resists puncture and abrasion better than loose weaves. Canvas and denim typically measure 15, 28 ppi depending on grade. Shirting fabrics run 24, 32 ppi. Industrial filtration cloths and technical textiles may exceed 80 ppi for specialized applications.

How ppi is measured and specified

Ppi is counted visually under magnification or by digital image analysis of the fabric cross-section. Specifications appear in purchase orders and technical data sheets alongside thread count (total ends plus picks per inch). Variations in yarn thickness and weave structure can make ppi inconsistent across a roll, so quality control labs sample multiple points. Shrinkage during finishing alters ppi after weaving; a fabric may measure 22 ppi on the loom but 20 ppi after scouring and drying.

In practice, weavers use ppi to predict fabric hand, drape, and production speed. Higher ppi requires slower loom speeds and stronger warp tension. A loose weave at 12 ppi runs fast but snags easily; a tight weave at 40 ppi is durable but stiff and slow to produce. Cost, performance requirements, and end-use determine the target ppi for each design.