String Action Gauge — Lutherie Encyclopedia

String Action GaugeType: toolA small ruler calibrated for measuring string height, nut slot depth, and pickup distance on guitars.## Description A string action gauge is a compact ruler, typically credit-card sized, with fine gradations on one or more edges calibrated in 1/64-inch or 0.5mm increments starting from zero at the bottom edge. Some gauges include additional scales for measuring string spacing, nut slot depth, and pickup-to-string distance. They are made from stainless steel or aluminum and often include reference measurements for common setup specifications printed on the face. ## Use in Lutherie During guitar setup, the string action (height of the strings above the frets) is one of the most important adjustable parameters. The string action gauge is placed directly on the frets to measure the gap between the fret top and the string underside at specific positions, typically the 12th fret and the 1st fret. It is also used to check nut slot depth, bridge saddle height above the bridge plate, and relief at the 7th fret. Consistent measurements across all strings ensure balanced playability. ## Selection Guide Stew-Mac, MusicNomad, Hosco, and several other brands offer string action gauges for 5 to 20 dollars. A stainless steel gauge with both imperial and metric scales is the most versatile. Some gauges include a built-in string spacing ruler and reference chart for common action specifications. The simplest and most durable option is a basic steel ruler with fine gradations from a zero edge. ## Tips - Measure action at the 12th fret with the guitar in playing position and tuned to pitch for…