String Length Guide - What Strings Will Properly Fit Your Bass?

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Why Do I Need This Information?

If there's a constant in the upright bass world, it's that there are no standards for size, design, or other aspects related to our instruments. One maker's large 1/2 size bass could be another maker's 5/8, or another maker's petite 3/4. Most of the basses on the planet are considered to be 3/4 size, so when a "non expert" refers to a bass as "full size" there is a good possibility that the instrument in question is actually a 3/4 size bass. Even if the bass legitimately is "oversized" -- as I mention in my Double Bass Sizing FAQ -- there are no strict dimensional "standards" for basses that are labeled as 7/8 and 4/4 size. So, you can't assume that two different so-called 4/4 sized basses will have the same dimensions. They can, in fact, vary a great deal. And even some basses that are identified by their maker as 3/4 sized can have design factors that create a need for strings that are longer than "normal" 3/4 size strings.

As such, strings can vary widely, depending on the maker, and whichever bass(es) they used when designing their specifications. So sometimes, basses that are a little "on the edge" of the normal size conventions may have some strings that don't quite fit.

An "average" 3/4 size bass has a scale length (mensur, playable length) in the neighborhood of 41-42 inches with an afterlength (suspended string length between the bridge and tailpiece) around seven inches. However, the afterlengths on a 3/4 size bass can vary, as the size of the tailpiece - and its placement in relation to the bottom of the bass - will affect those measurements. Therefore, if your larger bass is reasonably close to those numbers, a "standard" length string will probably do.

Most "standard" strings are designed for 3/4 and 4/4 size basses. Some have specific sets for each (Thomastik Spirocore is a common example, but the vast majority of players use the S42 set for both 3/4 and 4/4 sized basses.) Some, like the Zyex strings from D'Addario, have a special 4/4 length E-string (since its machine is the closest to the nut) but the A, D, and G strings all fit 3/4 and 4/4 sized basses. And then, there are outliers, like the Rotosound RS4000 strings, which are explicitly designed for 4/4 bass despite them being a far less popular size. Go fig.

This guide should provide you with some guidance, as we're providing some important measurements here to help you figure out whether a particular string will fit your particular bass. We don't go into tension here; keep in mind that strings that are designed to fit a 1/4 size bass MIGHT just fit an electric upright that has a very short afterlength - but those strings were designed for a much shorter scale, and if your electric upright has a more common 3/4 size scale, the tension on the strings may not be ideal. But that's another conversation.

How to use:

afterlength and scale length guide graphicSTEP 1:
First, you need to take two quick measurements on your current strings (or on your bass if there are no strings on it) so you can compare your bass with the string measurements we have, below.

Here's what you need (see graphic to right for guidance, click on it for larger version):

  1. Scale Length - This is the playable length of the string
  2. Afterlength - This is the string length that is suspended between the bridge and where the ball ends are captured in the tailpiece
  3. The sum of those two measurements - Add the two measurements together - easy-peasy!


Now, you can compare the measurements you took with the information below. We've included measurements for many common strings, and here is what you need to check for:

  1. Ball End Silk - this is how long the silk windings from the ball end of the strings travel up the string.
         • If this number is SHORTER than your afterlength measurement, you are good. Move on to step 2.
  2. Ball End to Pegbox Silk - This is the distance from the ball end to the top silk, which includes both the afterlength silks AND the playable portion of the string.
         • If this length is LONGER than your "sum of those two measurements" - you are good.


  • If we list a "range" of lengths, it's because the four different strings have slightly different measurements. Commonly, the E string is made a bit shorter, because on most basses, that's the one that has the shortest distance to the tuning machine once the string crosses the nut, and they're trying to avoid having too much of the playable portion of the string on the tuning peg.
  • These measurements have been taken by us, here at the shop. They may be imperfect; aside from us being human and occasionally making mistakes, sometimes manufacturers change specs without notifying us, and sometimes the machine operator winding the strings ends up making strings that are a little out of spec. If your numbers come out to be really close, think twice. And lay your new string out over the string path BEFORE cutting or winding it in case it comes up short!

The Chart


Ball End Silk
Ball End to
Pegbox Silk
Ball End Silk
Ball End to
Pegbox Silk
Corelli 3/4 Sets (370, 380, 360) 3.5 54.5 - 56.5 8.9 138.5 - 143.5
Corelli 350A 1/2 Size 3.5 52 8.9 132
Corelli 350B 1/4 Size 3.5 50 8.9 127
D'Addario Helicore 3/4 Size 5 54-55.5 12.7 137-141
D'Addario Helicore 1/2 Size 5 50 12.7 127
D'Addario Helicore 1/4 Size 5 45.25 12.7 115
D'Addario Kaplan 5 55-55.5 12.7 139.7-141
D'Addario Zyex 5

Note - 3/4 size E
string is short,
longer E string
is available

12.7 129.5-142.25
Eurosonic 3/4 Size 5 51-53 12.7 129.5-135.6
Innovation 5.5 14 51.5-53 130.8-134.6
Jargar 3/4 4.5 54.5-55.5 11.4 138.4-141
Kolstein Heritage 5 54-54.5 12.7 137.15-138.4
LaBella 7710 6 54 15.25 137.15
LaBella Supernil 3/4 6 58 15.25 147.3
Pirastro 3/4 (all) 4 55 10.15 139.7
Pirastro 1/2 4 51.25 10.15 130.2
Pirastro 1/4 3.3 46.3 8.4 117.6
Rotosound RS4000 (4/4) 7 62 17.75 157.5
Thomastik Belcanto 5 55 12.7 139.7
Thomastik Dominant 6 51.5-54 15.25 130.8-137.15
Thomastik Spirocore S42 (4/4) 6 54.5-56 15.25 130.8-137.15
Thomastik Spirocore 3885 (3/4) 5.5 52.5-54 14 133.35
Thomastik Spirocore 1/2 4.75 47.25 12 120
Thomastik Superflexible 6 54-56 15.25 137.15-142.25
Electric Upright Strings
GHS Crossovers 3/4
for NS Design Basses
1 46.5-47 2.54 118.1-119.4
D'Addario NS Electric
for NS Design Basses
2.5 46-46.5 6.35 116.85-118.1

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