Chord Construction
All chord types are based upon a unique formula which can be related back to the major scale that has the same letter name as the chord, e.g., C chords are based upon a formula that can be measured against the C major scale. Here is the C major scale written in both standard music notation and tab (tablature). If you play these notes you get the familiar Do Re Mi Fa So La Ti Do sound of a major scale.
The letter name of each note is written below the note on the staff ( 3 ). The number written below the letter name is the degree number of the note in the scale. These thirteen note degrees are all that is needed to create all chord types, each of which has its own unique formula.
C
The formula for the major chord is 
This means that the major chord consists of the first, third and fifth notes (degrees) of the major scale. Therefore the C major chord consists of the 1st, 3rd and 5th notes of the C major scale, i.e., the C E G notes. These notes can be in any order and can be duplicated, but there must be at least one of each of those notes in the chord. In the C major chord shape shown in the diagram, there is one C note, two E notes and one G note. To learn all these individual notes, see Progressive Banjo. The G major chord consists of the 1st, 3rd and 5th notes of the G major scale, i.e., the G B D notes.
The formula for a minor chord is 
which means that the minor chord consists of the first, flattened third and fifth notes of the major scale. The flattened third is simply the third note lowered by one fret (semitone). For example, the C minor (Cm) chord consists of the 1st, flattened 3rd and 5th notes of the C major scale.
The following chord formula chart lists all the chord types in this book along with its formula (relative to the major scale) and an example based upon C. A full understanding of chord construction is very useful as your playing ability advances as it is particularly useful when improvising, substituting or writing an accompaniment for a song or piece of music.
