The guitar fretboard, read as a ruler
Six strings, one fret per semitone, and two rules that spare you memorising the two hundred and some notes of the neck.
The guitar neck looks like a maze: six strings, twenty frets, and the same note scattered in places that look nothing alike. It is not a maze. It is a chromatic ruler, repeated six times with known offsets.
One fret, one semitone
Each fret raises the string by exactly one semitone. Twelve frets later you are back at the same name, an octave higher.
Nothing more needs to be known about the distance between frets. The rest of the neck follows from that rule and from the tuning.
The tuning, and the exception it hides
From the lowest string to the highest: E, A, D, G, B, E.
Between neighbouring strings there is always a , five semitones. Always, except in one place.
The fifth fret of a string gives the same note as the next string open. That is how the guitar is tuned by ear, and it is the rule that turns six independent rulers into a system.
The exception is between the third and second strings, G and B: there the distance is a , and the note repeats at the fourth fret, not the fifth.
The same note, in several places
A direct consequence: one sound has several addresses. These three positions are the same note, .
Play the three and the ear cannot tell the pitch apart, only the timbre, because the thicker string stretched sounds different from the thinner one relaxed. Choosing between them is a decision of fingering and colour, never of tuning.
Shapes, not frets
Here is what the keyboard does not offer. A chord on the guitar is a shape, and the shape does not change when you move it.
Start with the most open of all, :
Three open strings do the work. Now push everything up one fret and lay the index finger across where the nut was: what was an open string becomes fret 1.
It is . Same shape, a semitone higher. Keep going up:
. One shape, twelve keys, and that holds for every shape that does not depend on open strings.
Strings that do not sound
Not every shape uses all six strings. Two marks above the nut say what to do with the ones left over:
- ○ — open string, let it ring
- × — muted string, do not let it sound
. The sixth string is muted because an E in the bass would change the chord: it would become , which is legitimate but is something else.
, for the same reason.
What to take from this
Two rules are enough to memorise nothing:
- One fret is one semitone.
- The fifth fret equals the next string open, except between G and B, where it is the fourth.
From them follow the location of any note, the reason the same note appears in several places, and the reason a shape learned once serves all twelve keys. The neck is not a map to memorise; it is a ruler to read.