Pile Weight
You will often see a term called pile weight, also referred to as tufted face weight or sewn face weight. This measures how much the yarn weighs per square yard, excluding backing or infill, and is measured in ounces per square yard or grams per square meter. If you only want one measure of your carpet, pile weight is the best as it takes into account both the height and density measurements listed below. Generally speaking, the higher the pile weight the better quality and higher durability the turf. At the low end of the spectrum you will see pile weights of 28 oz per square yard or less. At the higher end of the spectrum you will see pile weights of 106 oz per square yard or greater. And there is a quite a large range in between.
Pile Height
The Pile Height is the height of the turf’s blades and is typically 1.50 to 1.75 inches, although much shorter (e.g. 0.31 inch) and taller (e.g. 2.625 inch) varieties exist. Often you will see a measurement for both the grass length and the thatch length, with the thatch length a bit shorter. Generally speaking, unless you have a specific turf application requiring shorter blades (e.g., golf putting greens), be wary of shorter, generally cheaper pile heights of less than 1.50 inches.
Gauge
You may want to also consider the turf’s gauge. Carpet is formed by stitching together the individual blades of grass in rows on a backing at pre-set widths. Gauge is the distance or width between those rows. In the United States this is measured in fractions of an inch with typically gauges of 5/16″, 3/8″, 1/2″ and 3/4″. The gauge you select is partially based on preference and partially based on function. For example, closer gauges mean tighter-packed grass blades and might be used for, e.g., a golf putting green. Wider gauges may be better for athletic fields. For standard artificial lawns, most gauges seem to fall in the 3/8″ to 3/4″ range and, generally speaking, a closer gauge means a heavier artificial lawn which is generally considered higher quality.
Stitch Rate / Stitch Count
A final consideration is the stitch rate or count. This measures the number of blades or tufts per square inch and, similar to gauge, is a measure of the density of the grass blades on the carpet. Stitch rate is typically measured in the number of stitches in a 3 inch by 3 inch piece of turf. Generally speaking, the higher the stitch rate, the heavier and higher quality the grass.
