Fast, accurate measurements for setups.

Our String Action Gauge is a "Swiss Army Ruler" for setup adjustments on any stringed instrument.

This pocket-size stainless steel rule has become a luthier's fav...

Buy Now From Amazon

Product Review

Fast, accurate measurements for setups.

Our String Action Gauge is a "Swiss Army Ruler" for setup adjustments on any stringed instrument.

This pocket-size stainless steel rule has become a luthier's favorite in busy shops. It's the best way yet to get vital measurements on acoustic and electric instruments.

• String height

• Bridge saddle height

• Saddle slot depth

• Fret slot depth (unbound fingerboards)

• Nut height

• Pickup polepiece height

No more "three-and-a-half-64ths or 3/32" plus one of those little lines." This gauge measures in ways that regular rulers can't.

—Dan Erlewine

Developed here at Stewart-MacDonald by Dan Erlewine and Don MacRostie, the gauge features a progressive string height scale: simply slide it across the frets and read the measurement under the string. It's faster to use than any ruler, and stays parallel to the fingerboard—much easier than trying to hold a ruler perpendicular to a rounded fret.

The string height markers are graduated from .010" to .140".

The back of the gauge has a time-saving fractional/decimal/metric conversion chart.

The String Action Gauge is made of durable stainless steel with precision-etched markings, and fits right in your pocket.

Tip: You can use the gauge to set router depth, instead of a shop ruler. It sits solidly on your router base, with the scale right where you need it.



  • BUILT TO LAST A LIFETIME: All StewMac tools are backed by our Lifetime Promise for professional-grade durability
  • FAST & ACCURATE MEASUREMENTS: Precisely measure string height, nut slots, saddle depth, and pickup polepiece height for perfect guitar setup
  • PROGRESSIVE STRING HEIGHT SCALE: Simply slide across the frets for quick and easy action readings—faster than a standard ruler
  • MULTI-PURPOSE TOOL: Can also be used for setting router depth, providing more accuracy than a standard shop ruler
  • STAINLESS STEEL PRECISION: Durable, long-lasting tool with precision-etched markings for clear and reliable measurements
  • BONUS CONVERSION CHART: Includes a fractional/decimal/metric reference chart on the back for quick calculations

Similar Products

StewMac Understring Radius Gauge Tool, Set of 9, Standard Width for Guitar Setup, Stainless SteelMusic Nomad MN207 Premium Instrument Work Mat and Cradle Cube Neck SupportThe Guitar Player Repair Guide - 3rdGuitar Neck Straight Edge (Notched) Luthiers ToolCreanoso Guitar Truss Rod Allen Wrench Adjustment Tool for Martin Acoustic GuitarsGuitar Notched Straight Edge and FRET ROCKERHow to Make Your Electric Guitar Play Great - Second Edition Bk/online mediaOEMTOOLS 25025  26 Blade Master Feeler GaugeFender Locking Tuners ChromeGibson Vintage Reissue Electric Guitar Strings, Light 10-46