Guitar Scale Length Explained: String Tension & Playability

Guitar Scale Length Explained: String Tension & Playability

How does your guitar’s scale length affect guitar string tension & playability? We talk about the effect of different scale lengths as well as how to adjust your strings to balance it out.

Guitar Scale Length Explained: String Tension & Playability

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 Transcription

Have you ever wondered how scale length affects the tension of the strings on your guitar? If you take one guitar with a longer scale length, you put the same set of strings on it as you do a guitar with a shorter scale length, which is going to have more tension? Today, we’re going to solve that question for you, give you a few pointers as to how to pick the right set of strings for guitars at different scale lengths.

The tension on any given string on your guitar is a product of the scale length, the tuning, and the mass of that individual gauged string. As a result, when you increase the scale length on your guitar, you’re going to have more tension, even if you’re tuning to the same pitch and keeping your gage of string the exact same. What this means is, on a 27-inch scale guitar, a set of 10s tuned to E standard is going to have quite a bit more tension on it than that same set of 10s tuned to E standard on a 25-1/2 inch scale guitar. Conversely, if you have, like, a 22-1/2 inch scale guitar or something around there, a set of 10s is going to feel way, way lighter. It’s going to have not nearly as much tension as it would on a standard scale guitar.

This, in effect, is the reason that a lot of players will use longer scale length guitars in order to tune down. Because of that longer scale length, you don’t need to go as heavy in gauge in order to tune down than you would typically. For example, if you wanted to tune a 25-1/2 inch scale guitar down to, like, B to B baritone tuning, you might have to use something like a set of 13s. Whereas, if you have a 27-inch scale guitar, you might be able to get away with something like 12s. That means that it’s just going to be a little bit more natural feeling to you, you’re not going to have to make that big compensation to having a way heavier set of strings on your guitar, but you can still effectively hit that tuning and keep everything under proper tension.

Where things get more interesting is when we’re making more incremental changes to scale length, because every string on your guitar isn’t going to react exactly the same to a given change in scale length. In general, the difference in diameter on a given gauge string is going to have a more pronounced effect on the smaller gauged strings on your guitar. The plain steel strings are the best example here. The difference between a 9 and a 10 is far more pronounced in terms of tension than the difference between a 46 and a 47 or something like that.

In practical terms, let’s imagine that you have two different guitars. One is a 25-1/2 inch or Fender style scale length, and the other is a 26-1/2 inch scale length. On the Fender style 25-1/2 inch scale length, let’s imagine you have just a standard set of 10s from 10 to 46. To get your 26-1/2 inch scale length guitar to play the exact same as your 25-1/2 inch scale length guitar, you’re only going to need to make incremental changes when it comes to the plain strings, and you’ll be able to make larger changes when it comes to the wound strings.

In effect, if you went with something like a 9-1/2 on the top end of your 26-1/2 inch scale length guitar, it would feel fairly comparable to a 10. In actuality, it would have a little bit too little tension, but at a certain point here we can only get so specific when it comes to gauge. At the same time on the bottom end, going from a 46 on that 25-1/2 inch scale length, you could go all the way down to a 44 on the longer 26-1/2 inch scale length, and you’d be right in the ballpark of what that tension would be on both guitars.

Now, the good news is you don’t really have to worry about becoming a math expert or really trying to dial everything in perfectly, because most guitar string sets are already constructed in a way that’s going to echo this basic mathematical principle when you just go down a gauge. A good rule of thumb to keep in mind is that a 1/2 gauge difference in the overall gauge of a set, so here I’m talking about the difference between a general set of 10s and a general set of 9-1/2s or 10-1/2s, that 1/2 gauge difference, which of course would be balanced out over the entire set by the manufacturer, is going to be good enough to account for about a 1 to a 1-1/2 inch difference in scale length. If you get way bigger than that, if you’re having, like a 2-1/2 or a 3-inch difference in scale length, then you’re going to want to go a full gauge difference.

Again, in practical terms, if you have a few different guitars with different scale lengths that you want to play really similarly, let’s say you have a set of 10s on your 25-1/2 inch or 25 inch scale guitar, once you get up to about 26, 26-1/2, or 27 inch scale length, you’ll want to go about a 1/2 gauge down in order to match the same tension at the same tuning. If you get all the way up to something like a 28-inch scale length or more, you’ll want to go a whole gauge down, all the way down to, like, a set of 9s.

Now, the inverse is also true as well. Let’s imagine that you had that same 10 gauge set on a 25-1/2 inch scale, and you’ve got something with a 24-inch scale length, you’ll want to go with something like a 10-1/2 gauge set. If you get all the way down to, like, a 22-1/2 or another really, really short scale length, you’d want to go all the way up to 11s, again, if your desire is to overall balance out all the tension between all of those different scale length guitars in your arsenal.

Now, is this a requirement when you have guitars at different scale lengths? Absolutely not. Maybe you like just using a set of 10s on all of your different scale lengths. You like how it feels a little bit stiffer at, like, a 26-1/2 inch scale length and you like how it’s super bendable on, like, a 22-1/2 inch scale length. That’s totally fine. If you really like to feel the difference in how your different guitar’s scale lengths affect the playability, keep your strings the same and just experience that difference for what it is. However, if you’re trying to account a little bit better for the difference in scale length, then I would keep these rules of thumb in mind order to help guide you into what is the right set for you.

Now, what if you’re using a different tuning on top of also using a different scale length on a given guitar? That’s where things can get a little bit more complicated. At String Joy, we prefer to handle those things yourself. If you send an email to [email protected] somebody will really work with you to help you dial in exactly what your particular guitar needs on it in order to sound right at a given scale length and a given tuning. If you prefer to do everything yourself, there’s a couple different string tension calculators on the internet that can be useful, but again, I really recommend reaching out to us because we’re more than happy to help you dial it in just right.

What do you think? Do you prefer to use the same gauge string on all of your different scale length guitars, or do you prefer to balance them out a little bit with different gauges of strings on each one? Let us know down in the comments.

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10 Responses

  1. You state that the string tension to reach pitch is dependent on the scale length, but doesn’t the overall string length have anything to do with it ??
    For example:
    Two guitars have the same scale length, however, one uses a gibson style tune-o-matic tail piece and the other uses a short trapeze type tail piece. The total string length from tuner to tail piece must be tensioned and not just the length between the bridge and the nut, therefore, is it not true that it is not the scale length that determines the tension on a string but actually the overall string length between the tuning key and the tail piece ??
    If it were only dependent of the length between the nut and the bridge then why isn’t the string slack between the bridge and the tailpiece ??

    1. The length of string behind the nut and behind the bridge has no effect on the tension of the string between the bridge and the nut and is thus disregarded when calculated playing tension of a string mathematically. That said, the length of string behind the nut and bridge is indeed held in a compensated tension along with the string, but increasing or decreasing the length of string behind either piece of hardware does not affect the tension of the string when played.

  2. I’m now in the difficult position of finding strings for a mutant baritone-range multi-scale 7-string guitar. The treble length is 30″ and the bass is 33″. The issue is the length of the strings. The D/4th string needs to be at least 37″ long to reach and get around the tuner, and 38 or 39″ would be easier to reach and wrap around the tuner. Few if any manufacturers post the string lengths.

    1. Hi Mark, not a difficult position at all — we publish our string lengths here at Stringjoy and they’re all plenty long for your instrument. We’re at at least 39.75″ winding length and 42-46.5″ total length.

  3. I’m building a solid body electric guitar and want to either go 19 3/4 or 22 1/2 scale can i I get away with a 13 inch length body?

    1. With a 19 3/4 scale, you can get away with a 13 inch body, but it might be more difficult on a 22 1/2 scale, depending on your neck pocket and neck design. I’m assuming you mean from behind the bridge or tail of the guitar to the end of the neck pocket, and if this is the case, you just have to make sure for the 22 1/2 that you have an appropriately scaled neck. For example, you’re going to need to give yourself approx 11.25 inches from the SADDLE to the reverse end of the 12th fret, with that same distance mirrored from the neck (11.25 inches from 0 fret or nut to the front end of the 12th fret). So long as your 12th fret isn’t positioned directly on the end of the neck pocket, you’re fine.

      With a 19 3/4 scale body, you want the same ration (1/2 scale) from saddle to reverse of the 12th fret and nut/zero fret to the front of your 12th. If this specific need isn’t met, your guitar build will be dead before you string it.

      Hopefully, though, you’ve already found the info you need. I’m just dropping this for anyone else that might have the same question on reading, hoping for an answer to yours.

    1. I’m going to answer both questions, starting with string gauge:
      The gauge will depend on what range you’re looking for and the tension your neck can handle. A steel reinforced maple neck can handle more tension than a wood neck without reinforcement, and an adjustable truss can handle even more. Likewise, it depends on how many strings you plan on putting on it. If it’s just a piece of kiln-dried pine you’ve cut for three or four steel strings to imitate an open tuning like a banjo, I’d recommend 11-32, with only the low string being wound (if any wound at all). It’s more dependent on the neck material and tuning than scale, though.

      So, answers ahead contain math. Lots of it. If you want to dodge the math lesson and just want a calculator, StewMac offers one.

      https://www.stewmac.com/FretCalculator

      To answer your question (hopefully you’ve already found the answer elsewhere, but for anyone else stumbling on this with a similar question) you’ll want to use what’s called the rule of 18. The more modernly calculated constant is actually 17.817 (some companies I think use 17.835, both yield consistently good results) but 18 provided decent compensation for gut strings and the lack of adjustable saddles.

      The more traditional equation gets the job done, but can lead to minor practically unnoticeable minor errors on 22+ frets. This is also why we generally use adjustable saddles.

      Example of the traditional equation

      22.5 scale gives us
      22.5/17.817 = 1.263 from nut to first fret, and the rest can be calculated by subtracting the previous value from your scale length.
      IE (22.5 – 1.263)/17.817 = 1.192 will be the distance between first and second fret, (21.237 – 1.192)/ 17.817 = 1.125 will be the distance from 2nd to 3rd,

      Though nut to fret is more reliable, as you can utilize a constant equation

      where B is the distance from bridge to fret, S is immutable scale, and n is the nut, with F as nut to fret,

      B[1] = S – F[1]

      F[2] = B[1]/17.817 + F[1]

      Or, to consider the nut as a zero fret, a more consistent equation could be

      B[n-1] = S – F[n-1]

      F[n] = (B[n-1]/17.817 + F[n-1]

      to find the bridge to nut distance and nut to fret distances of any given fret. These are far more reliable equations than going nut to nut, as going from nut to nut can cause minor issues past the 18th fret marker as rounding errors compound. The fret to fret formula should realistically mostly be used to double check your math after you’ve gotten your Bridge to Fret and Nut to fret numbers, to ensure they are the appropriate distance apart.

      The most modern equation is based specifically off 12th roots and can be painful if you aren’t using a calculator

      where d = distance from nut, s is scale, and n is fret number
      d = s – (s / (2 ^ (n / 12)))

      It’s going to be the most tonally accurate for guitars with low string heights and flat radii. It’s also the most pain in the brain.

      That’s all I’ve got.

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