I'm sure this must have been asked before but I'm finding myself incapable of phrasing the search query correctly to find it.

Guitar and bass (and more generally all 'necked' instruments) necks are usually (always?) between 1 to 3 mm thinner at the nut than they are at 12th fret. Are necks carved in this manner for playability or construction/structural reasons?

In a very large neck, like 6 string bass or 8 string guitar, a 2 mm difference of thickness, nut to 12th fret, wouldn't be too noticeable compared to the bulk of the neck volume in your hand. Moreover, the neck width and therefore its volume decreases anyway moving up to the nut. So what justifies the extra effort to have this slight slope at the back of the neck?

By the way, what is the name of this difference in thickness? Searching for "slope", "angle", "thickness" etc. yielded results about neck to body angle, or topics of "fast/shredder necks" instead.

  • 1
    Does this answer your question? Why does the neck of a bass get wider?
    – Neil Meyer
    May 8, 2022 at 17:55
  • @NeilMeyer The question you've linked to regards the width of the neck across the strings (i.e., side to side). This question regards the thickness of the neck from fingerboard to thumb-side (i.e., front to back). Are you saying that the answers are the same, even though the questions themselves are different?
    – Aaron
    May 8, 2022 at 19:40
  • FWIW this is true of bowed string instruments as well, for the same reason. May 9, 2022 at 17:12

3 Answers 3


Mechanics. The neck has to resist string tension. If the neck gives/bends near the nut, that does not make any difference with regard to string length so the string tension cannot make much of a difference at that place. In contrast, bending near the neck mount will effect a much more significant difference in string length, so the string tension is much more likely to cause a difference there.

  • This physicist approves :-) May 9, 2022 at 17:11

Do you mean thickness front to back (fretboard to underside), or side to side (top string to bottom string)?

Either way, both change from one end of the neck to the other. Several reasons. one is that the strings are never parallel, top to bottom. They need to be wider at the body end, for r.h. playability, but that negates itself at the head end - no reason to be as wide there.

There's also the tension on the neck, alongside fixability to the body. There's more tension in the neck at around its mid-point - about where the neck joins the body. So thicker here is structurally a good move. It also means the heel isn't too abrupt.

The section also changes - different in different makes and models of guitar/bass - that is, the cross-section shape of the neck itself, D and C express a couple of shapes.

Taper could be the keyword you're searching for!

  • Thanks for your input! Yep, I meant front to back or "taper". I'm obviously not a native english speaker and that word alone did magic on google! Thanks a lot really!
    – geeheeb
    May 8, 2022 at 11:47

It could be that a tapered neck facilitates fretting, where the neck is more narrow, and plucking/picking, where the neck's taper results in a wider string spacing towards the guitar's bridge.

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