Understring Radius Gauges

  • 142 Reviews
  • Write a review

Fast, accurate bridge saddle adjustment.
Each of these unique gauges has an accurately radiused arc on both the top and bottom surfaces, and is shaped to fit easily under the strings.

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Set of 9

Item # 0353
In stock, ready to ship!



17" gauge only

Item # 0352
In stock, ready to ship!


Total: $0.00
Quantity: 20


Radius gauges for guitar work

Dan Erlewine demos the three kinds of radius gauges for setup and fretwork.

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Fast, accurate bridge saddle adjustment.
Each of these unique gauges has an accurately radiused arc on both the top and bottom surfaces, and is shaped to fit easily under the strings.

Use the bottom curvature to determine your fretboard radius, and the matching top curvature becomes a reference for setting string saddle heights for best playability.

Set of 9 now includes new 17" radius for Ibanez guitars!

Find your fretboard radius, and set your bridge saddles to match. They're handy for matching pickup polepiece heights to the arc of the strings, too. Precision laser-cut from .050" stainless steel.

The set of 9 gauges includes:
7-1/4", 9-1/2", 10", 12", 14", 15", 16", 17" and 20" radii.

They'll work for string spreads and fingerboards up to 2-5/8" (66.68mm) wide.

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Fixing fret buzz: raising the saddles

A P-Bass with fret buzz: Dan Erlewine fixes his brother’s bass, and answers the question, “To get rid of this fret buzz, should I adjust the saddles or the truss rod?”

Ratings & Reviews

Understring Radius Gauges

  • Based on 142 Reviews
Displaying 2 of 15 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
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Multi use tool

By Marcio Costa from Brasil
(Customer's Reviews) Sunday, February 02, 2014

I use mine for under string adjustment, "over string" adjustment, nut shaping, even pickup pole profiling. Also good to investigate and spot fake necks (most signature fenders are 9.5, and most gibsons 12"). I like to check fret seating too (a small flashlight and the corresponding gauge do the trick).

Very helpful gauges

By WBR Guitars from USA
(Customer's Reviews) Saturday, February 01, 2014

Another item I put off buying in favor of making my own from online printouts, to bending a piece of wire to match the radius. These take all the hassle out, and showed me where I was off with my homemade gauges! Worth the price and very well made.

Smooth Sailing

By Brian J. Kelley from New Jersey
(Customer's Reviews) Sunday, January 12, 2014

I am truly impressed with the ease of use of the Understring Radius Gauges. Up until that point, the action on my bass was too high and uneven across the neck. Now the action is low and silky smooth. A must have tool for ALL basses and guitars. Thanks again StewMac...

Fundamental tool

By Sylvain from Matane Qc
(Customer's Reviews) Sunday, November 10, 2013

Great and simple. Precise construction!
Many application with it.


By geetar_geek79 from North Hollywood, CA
(Customer's Reviews) Monday, October 14, 2013

I cant survive without these. It was my first time leveling and setting up my guitars and it works!

Yes it is

By pablopuerto from Chile
(Customer's Reviews) Thursday, September 12, 2013

This is a start point to setup your instrument. Very useful and good price.

Handy Tools

By Andrew H. from South Carolina, USA
(Customer's Reviews) Thursday, September 05, 2013

These are pretty cool, can check the radius both ways. I just wish I could have only bought the gauges for the radiuses I use.


By Paul Richard from Oshawa,Canada
(Customer's Reviews) Monday, August 19, 2013

I used these to set up My new Les Paul Standard and discovered that not all LP's have a 12" radius. Mine actually has a 17" radius. Takes all the guess work out of play instantly and it gives the confidence to set up any guitar that comes my way! I always wondered where I would get the tools I need to set up shop,now I know. Thank You for being there. Sincerely, Paul!

Absolutely essential

By Bill0294 from Clearwater, FL
(Customer's Reviews) Sunday, August 18, 2013

These crafty tools allow a level of excellence in set-ups that just can not be achieved with standard radius gauges. Nicely done. I have been surprised by several guitar's neck radii after using these. One of my "10"'s are actually a 9.5. One tele was a 12 when I assumed it was a 10!

Another "Must Have" from Stew-Mac!

By Dave Ward from Oklahoma City, OK
(Customer's Reviews) Tuesday, August 06, 2013

These are great gauges. These save me time and effort when doing setups. No guess work, no "eyeballing", just find the correct radius and know that your setup will be correct and consistent. Well worth the money spent!

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Shown on page 17 of our latest catalog.