Metric String Action Gauge

How to determine string action with the Metric String Action Gauge.


Measure string action (the height of the string above the fret) at any point by placing the gauge behind the string. The string height markings are at increments of .25mm (1/4mm). When the bottom of a mark aligns with the bottom of the string, that measurement is the string height at that point.

The markings themselves are .1mm thick, so referring to the top of a mark instead of the bottom adds .1mm to the measurement. In this way the progressive string height scale measures in .1mm increments.

String action specs
The suggested measurements listed here refer to the string height at the 1st fret and also at a higher fret. Measured for the outermost bass and treble strings.

Lay a straightedge across the frets and measure the clearance at the 8th. (Or put a capo at the 1st fret and press a string down at the highest fret — the string becomes the straightedge.)

Suggested action settings (in millimeters)

Steel-string acoustic guitarBass ETreble E
Action at the 1st fret .6 .35 
Action at the 12th fret 2.3 1.8 
Relief: .05 at the 8th fret     
Nylon-string acoustic guitarBass ETreble E
Action at the 1st fret .8 .6 
Action at the 12th fret 4 3.2 
Relief: .05 at the 8th fret     
Electric guitarBass ETreble E
Action at the 1st fret .6 .25 
Action at the 12th fret 2 1.6 
Relief: .025 at the 8th fret     
BassBass ETreble G
Action at the 1st fret .55 .5 
Action at the 17th fret 2.7 2.4 
Relief: .356 at the 7th fret     
MandolinBass GTreble E
Action at the 1st fret .8 .5 
Action at the 17th fret 1.9 1.7 
Relief: .13 at the 6th fret     
BanjoBass DTreble D
Action at the 1st fret .95 .9 
Action at the 12th fret 2.3 2.3 
Relief: .2 at the 8th fret     
Soprano and Tenor UkuleleBass GTreble A
Action at the 1st fret .38 .38 
Action at the 12th fret 2.29 2.29 
Relief: .05 at the 12th fret     

For more information on setups, including setup preferences of
famous players, see Dan Erlewine's Guitar Player Repair Guide
and How To Make Your Electric Guitar Play Great!