How Do I Know What Gauge My Guitar Strings Are?


There has probably been a time in your life at least once where you picked up a new or used guitar and wondered what gauge the strings were because you liked the way they felt. Or maybe you used my guide to determine that they need to be replaced but you don’t know what gauges they are.

Another common scenario is that a technician or luthier needed to figure out the guitar strings’ gauges because a client wanted the exact same set-up but they forgot to tell them what strings they use. Thankfully, there are a few ways of figuring this out, however, there is one method that is far superior than the others.

To know what gauges your guitar strings are, use a digital caliper, specifically one that allows you to measure the strings at 1/1000 of an inch or three decimal places (if you’re using the metric system). There are a few ways of determining gauges without a caliper, however. 

While there are other options available to the person who doesn’t want to spend a dime, there’s no doubt that using a digital caliper such as the Preciva from Amazon is going to be the most accurate and most reliable way of figuring out your string gauges. As a general rule, the more money you spend on your digital caliper, the more accurate the reading will be, however, not everyone is willing to spend money just to figure out the string gauges, so we’ll explore other options as well. 

by the way, if you’re trying to get a better grasp of guitar chords, scales, tunings, and techniques in the most efficient, practical, and convenient way possible, I couldn’t recommend Guitar Tricks enough. It’s the learning platform I use and you can sign up here for free.

1) The Best Way – How to Measure Your String Gauges with a Digital Caliper 

Digital Caliper for Measuring String Gauge

Grab a digital caliper from Amazon like the one I linked above. What this handy tool does is it allows you to clamp down on the strings to figure out the exact diameter. After grabbing onto the string, the digital caliper will actually say how thick it is either in millimeters or in inches, depending on what you want to use or how you set it up. 

While a digital caliper is undoubtedly the best way to figure this out, I have to admit there is a very small learning curve to using one, which many of you will likely know if you’ve ever taken any kind of shop or woodworking class. But after a few tries, you’ll figure it out and then you’ll wonder how you ever struggled with it, to begin with. We’ll explore what these little issues are in a moment (they’re not a big deal). The first step is to just lay your guitar on its back somewhere safe and accessible.

A) Lay the Guitar on its Back 

Guitar on Its Back

As I just mentioned, the most important thing to do right away is to lay the guitar on its back with the neck slightly protruding upward to the ceiling. I do this by setting the guitar on my desk like what you can see in the image above. Then, I place a pillow underneath the neck, and then it’s ready for me to get the caliper. The reason why I put the pillow under the neck is just because there is something that bothers me about resting the tuning pegs on hard surfaces.

B) Zero the Caliper and then Measure the String

Zeroed Caliper

First, you want to close the claws of the caliper completely and make sure you’ve zeroed it out. Do this by pressing the button on top of the caliper. This is an important part, because you want to ensure that you’re actually getting an accurate reading. If you don’t zero the caliper first, you’ll get a weird reading and you’ll be even more confused than when you started.

After you’ve zeroed the caliper, place the guitar string inside of it and close the jaws onto it until you can’t close it anymore. Remember when I talked about the caliper’s learning curve? Knowing to zero the caliper and also not squeezing the string too hard is what I’m talking about. There’s no sense in applying too much pressure. Just squeeze it enough so it won’t close anymore, and then you’re good.

C) Take a Look at the Digital Caliper’s Screen 

This image has an empty alt attribute; its file name is Digital-Caliper-0.052--1024x509.jpg

The number you see on the caliper’s screen is the string gauge. Depending on the accuracy of your digital caliper, you’ll likely see a number that is either exactly in accordance with a common string gauge, or at least very close to one. For example, one of the most common string gauges for a high e-string would be 0.010″, which typically comes with strings that go all the way up to around 0.046.” 

It’s worth mentioning that people often use whole numbers to refer to strings that are actually measured via multiple-decimal point numbers. For instance, guitarists and others use the term “9s,” “10s,” or “11s” to refer to strings that are not actually 9 inches (obviously). A so-called “9’s” true measurement is actually 0.009,” the measurement of a “10” is 0.010,” and – you guessed it – the measurement of an “11” is 0.011.”

Remember that most guitar strings are manufactured in the United States, and if they’re not, they’re at least measured in this way: 1/1000 of an inch, or, in other words, one-one-thousandths of an inch (also called one thou). 1/1000 inch is 0.0254 mm, just to put it into perspective if you’re outside of the United States of America. If your string measurement is between a common gauge number, just compare and contrast it to the chart shown below that way you know where you stand.

D) Measure Every String and Write Down the Gauge 

Digital Caliper 0.0415

After you’ve figured out your first string, you have to go through and measure every single one to determine what the gauge is. Once you’ve written down every single number, you’ll have a much better idea of what the strings’ gauges are. It’s important to at least measure 2-3 of the strings, because one string on its own won’t tell you what you want to know. It could in some cases, but the more strings you measure, the more informed your decision will be. Alternatively, a quick way to save some time might actually be to measure the high e-string and the low e-string.

From there, you can simply assume the rest of the gauges will fall in line. For example, if the highest e-string is a 0.010″ gauge, there is a pretty good chance the low e-string will be a 0.046″ gauge. Additionally, by using the chart that I’ve shown you below, you’ll be able to surmise the string gauge even if it isn’t a 0.046. For instance, if it’s a 0.052, you’ll know that you probably have heavy top and skinny bottom strings on there from Ernie Ball – on Amazon.

E) Compare and Contrast your String Gauges to the Chart 

Do as the sub-title suggests and compare and contrast the string gauges to the comprehensive chart you can see below. You’ll notice that I actually compiled a chart of some of the most popular string gauges, that being light, medium, heavy, super light, baritone, and light-top/heavy bottom. You should have a good idea of where you stand by comparing them to the chart shown here. By the way, this chart is for electric and not acoustic guitar strings, which, you’d know are different if you’ve read my article on the subject.

Guitar String Super LightRegular/Light Medium Heavy Baritone Light-Top/Heavy Bottom
E0.0080.0100.0110.0120.0140.010
B0.0100.0130.0160.0170.0180.013
G0.0150.0170.0190.0200.0260.017
D0.0210.0260.0270.0280.0440.030
A0.0300.0360.0370.0380.0560.042
E0.0380.0460.0520.0530.0620.052

As I’ve already mentioned, this is obviously the best way of figuring out your string gauges, but not everyone is willing to spend the $20 or $40 (and sometimes, more) to figure out their string gauges. There is no judgment here; maybe you just need to know the strings gauges this one time. 

Alternative Ways Of Figuring Out Your String Gauges (That Still Work)

2) Compare and Contrast Single-Bought Strings 

Single Bought Strings

The second way of figuring out your string gauges is to compare and contrast your strings to a single string you’ve purchased from a guitar shop. For example, you could go to a guitar shop and buy a 0.009″ gauge string, a 0.010″ gauge string, a 0.011″ gauge string, and a 0.012″ gauge string. How would this help you? Essentially, you would take your high e-string and compare it to all of the strings that I just mentioned to determine which one is closest.

Once you’ve figured out that it’s a 0.009″ gauge string or a 0.010″ gauge string, then you pretty much know that the rest of your strings are probably light or regular gauge. 9s, 10s, 11s, and 12s are the high e-strings on some of the most common gauges, so if you’ve got a 0.012″ on the high e-string, there is a good chance that you have heavy gauge strings.

Truthfully, there is an issue with this method because different manufacturers have mixes of high and low tension strings, for example, most makers have skinny-top heavy bottom strings, as Ernie Ball calls them, or heavy bottom/light-top as D’Addario refers to them on Amazon as well. So this method might take you for a loop. 

For the most part, however, most guitarists just stick with one of the main string packages, like light, super-light, medium, or heavy, which are commonly the same gauges right across the board for different guitar string manufacturers. With that said, I still think it’s worth the time, money, and effort, to just use a digital caliper instead, especially if you think you’re going to need to do the same thing again sometime in the future (which you probably will).  

3) Look to See If the String Ball Ends are Color-Coded

Ball Ends

D’Addario fans know that the company actually color-codes their string ball-ends so you know what you’re working with, just in case you drop them or mix and match by accident. Some manufacturers like Ernie Ball actually do the same thing, although, there are a few that don’t. Maybe you’re one of the lucky ones who is dealing with a set of strings where there are multi-colored ball ends that you can simply look up online. 

String Color Coded System

Important Things to Note About Measuring String Gauges 

1) The Digital Caliper is the Best Way Without Question

Digital Caliper is the Best Way of Measuring Guitar Strings - Without Question

I think that using a digital caliper is going to be your best bet here, although, I did include some other alternatives just in case you’re the type of person who only needs to figure out the string gauges once. With that said, I think a digital caliper is a great tool to have for many other purposes, and you’ll probably end up needing one someday in the future so you might as well just get one. I actually used mine today because I was curious about what strings I had on my PRS SE Custom 24 – one of the best budget-friendly guitars on ZZounds.

YouTube Video Tutorial

How Do I Know What My String Gauges Are?

Gear Mentioned

All of the links take you to Amazon except where noted otherwise

1) Digital Caliper from Preciva

2) D’Addario Light-Top/Heavy Bottom Strings (3-Pack)

3) Ernie Ball Skinny-Top Heavy Bottom (3-Pack)

4) PRS SE Custom 24 on ZZounds

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