Carpet
Pile height is paid for twice. The tuft goes down and it comes back up.
— g/m2
Pile yarn only, above the backing
Face weight here is pile yarn above the backing and nothing else: no primary backing, no latex, no secondary backing, so it is the figure a specification means by face weight rather than the total weight of the carpet, which is substantially higher. The yarn per tuft is twice the pile height plus a stated allowance, which is the geometry of a tuft that goes down and comes back up; real consumption runs a little above it because yarn is taken up over the needle and because pile height is measured after the carpet is finished rather than as it is tufted. Loop pile and cut pile take the same length for the same finished height, but a cut pile is measured to the tip of the cut yarn, so entering the same number for both understates the loop construction. Pile density is face weight over pile height and is the number that separates two carpets of equal face weight, one of which is dense and short and will wear, the other tall and sparse and will not. The line supply figure assumes the whole output goes to this construction at this count, which is a planning number rather than a schedule.
BCF Carpet Face Weight, Pile Yarn Consumption & Line Supply — free, with the formula and a worked example, at Textile School.