Guitar String Gauges in MM: A Helpful Guide

Guitar String Gauges in Millimeters

While there are guitar string manufacturers and brands all over the world, a pretty healthy concentration of the most popular string makers on the planet just so happen to be in the US—D’Addario in New York, Ernie Ball in California, Stringjoy (hey that’s us!) in Nashville, Elixir/WL Gore up in Delaware, DR in New Jersey, etc, etc. The downside of this for non-US guitar players—which we assume by volume is more of the total guitar-playing population than otherwise—is that you rarely see guitar string gauges in MM.

Well, to our global friends, worry not, because this short guide will help you convert any guitar string gauge you see into metric MM in a flash.

What are guitar string gauges measured in?

First, a very short primer. “Gauge” is a bit of a misnomer when it comes to guitar strings…

If you know anything about wire, you know that it’s commonly measured in Standard Wire Gauge (SWG) or American Wire Gauge (AWG) (if you want to turn this into a real internet wormhole, you can see how these two gauging systems compare here), and in these systems, the higher the number, the finer (smaller) the wire is. If we called guitar strings by their AWG number, instead of your guitar string set reading .010 – .013 – .017 – .026 – .036 – .046, it would read, approximately, 30 – 28 – 25 – 22 – 19 – 17.

Obviously, we don’t do that. So what the heck is this “gauge” that we speak of?

Well, it’s simpler than you might think. When you see a number on a guitar string—let’s say it’s a “10” or “.010″—that number is simply the diameter of a string in thousandths of an inch. So a “10” is a .010″ (.010-inch) diameter wire. Easy enough, right?

How to convert guitar string gauges into MM

Because this “gauge” is just a stand-in for thousandths of an inch, guitar string gauges as you typically see them are inherently imperial, and not very metric-friendly. Fortunately, the conversion is pretty simple.

If you are out and about trying to convert a guitar string gauge to MM, all you need to do is multiply the imperial guitar string gauges by the constant 25.4.

Thus, a “.010” multiplied by 25.4 becomes .254 MM, a .013 multiplied by 25.4 becomes .3302 MM and so on.

Do watch your decimals when you’re doing it this way, as you know as a guitar player there is a big difference between a “10” and a “100,” but in decimal form, a .010 and a .100 are easy to confuse.

Guitar string gauges in millimeters chart

You didn’t think we were going to leave you hanging to do all that math for yourselves, now did you?

Use the below chart to see the millimeter value of any common guitar string gauge for your electric, bass, or acoustic guitar, and if you find yourself doing this often, simply bookmark this page so you can come back to it whenever you need.

We included all of the gauges of guitar strings that we make here at Stringjoy, as well as some semi-common gauges from other manufacturers that didn’t make it into our balanced string sets.


Final notes…

We hope this chart is helpful for you! If there are any gauges we missed, or any tips or considerations we didn’t cover, let us know down in the comments.

And if you’re a guitar player (and let’s just assume you are since you’re here) you don’t want to miss joining the Stringjoy email list, it’s the best guitar newsletter on the planet, loaded with killer tips, tricks, and advice to help push your playing further. Sign up for it below!

3 Responses

  1. Hello, I can use some help choosing a set of strings. I have an Epiphone FT-140 guitar that I have owned for around 40 years but am just starting to learn to play. The strings are years old. I want to learn chords and Picking to play mostly Hymns and Folk music. I am just beginning, I know sheet music because I can play a saxophone, But I can only play one note at a time to follow the melody. Well that is where I am. Can you help me choose a set if strings. Thanks, Roger

  2. Wound Strings thinner than .018w like .017w, .016w, etc all the way down to .007w, etc we’d need to use a Special “microwound design” to make them stronger.

  3. I have acquired a vintage “ChromAlin” Autoharp (Rhythm Band’s version of the Oscar Schmidt “Guitaro”). There are 4 missing strings that I need to replace, but I don’t know the gauge strings I will need. I also don’t know if “regular” autoharp strings are long enough to use for this instrument ?

    I need Low C, Low E, Low F# and High C.

    Could you help me figure this out ?
    Also, how much would those strings cost (plus shipping) to order from your company.

    Thank you very much !!!

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