Carpet Manufacture
Gauge is a fraction of an inch. Across a twelve-foot machine that fraction decides whether you are threading 1,150 needles or 1,850.
— no.
Whole needles the gauge fits into the tufting width
Needle count is floored to whole needles, so the last fraction of gauge across the width is lost to selvedge rather than tufted. The count assumes a single needle bar with no shifting; graphics and staggered-bar machines place needles differently and the surface density no longer follows the gauge directly. Take-off speed here is the mechanical rate — real output is that figure times the running efficiency, which yarn breaks and pattern changes drive well below unity.
Tufting Machine Gauge to Needles per Width & Tuft Density — free, with the formula and a worked example, at Textile School.