Chord Names and Symbols (popular Music) - Rules To Decode Chord Names and Symbols

Rules To Decode Chord Names and Symbols

The amount of information provided in a chord name or symbol lean toward the minimum, to increase efficiency. However, it is often necessary to deduce from a chord name or symbol the component intervals which define the chord. The missing information is implied and must be deduced according to some conventional rules:

1. General rule to interpret existing information about chord quality

   For triads, major or minor always refer to the third interval, while augmented and diminished always refer to the fifth. The same is true for the corresponding symbols (e.g., Cm means Cm3, and C+ means C+5). Thus, the terms third and fifth and the corresponding symbols 3 and 5 are typically omitted.

   This rule can be generalized to all kinds of chords, provided the above mentioned qualities appear immediately after the root note, or at the beginning of the chord name or symbol. For instance, in the chord symbols Cm and Cm7, m refers to the interval m3, and 3 is omitted. When these qualities do not appear immediately after the root note, or at the beginning of the name or symbol, they should be considered interval qualities, rather than chord qualities. For instance, in Cm/M7 (minor-major seventh chord), m is the chord quality and refers to the m3 interval, while M refers to the M7 interval. When the number of an extra interval is specified immediately after chord quality, the quality of that interval may coincide with chord quality (e.g. CM7 = CM/M7). However, this is not always true (e.g. Cm6 = Cm/M6, C+7 = C+/m7, CM11 = CM/P11). See specific rules below for further details.

2. General rule to deduce missing information about chord quality

   Without contrary information, a major third interval and a perfect fifth interval (major triad) are implied. For instance, a C chord is a C major triad, and the name C minor seventh (Cm7) implies a minor 3rd by rule 1, a perfect 5th by this rule, and a minor 7th by definition (see below). This rule has one exception (see the first specific rule below).

3. Specific rules

   When the fifth interval is diminished, the third must be minor. This rule overrides rule 2. For instance, Cdim7 implies a diminished 5th by rule 1, a minor 3rd by this rule, and a diminished 7th by definition (see below).

   Names and symbols which contain only a plain interval number (e.g. “Seventh chord”) or the chord root and a number (e.g. “C seventh”, or C7) are interpreted as follows:

   • If the number is 2, 4, 6, etc., the chord is a major added tone chord (e.g. C6 = CM6 = Cadd6) and contains, together with the implied major triad, an extra major 2nd, perfect 4th, or major 6th (see below).
   • If the number is 7, 9, 11, 13, etc., the chord is dominant (e.g. C7 = Cdom7) and contains, together with the implied major triad, one or more of the following extra intervals: minor 7th, major 9th, perfect 11th, and major 13th (see Seventh chords and Extended chords below).

   For sixth chord names or symbols composed only of root, quality and number (such as "C major sixth", or "CM6"):

   • M, maj, or major stands for major-major (e.g. CM6 means CM/M6),
   • m, min, or minor stands for minor-major (e.g. Cm6 means Cm/M6).

   For seventh chord names or symbols composed only of root, quality and number (such as "C major seventh", or "CM7"):

   • dom, or dominant stands for major-minor (e.g. Cdom7 means CM/m7),
   • M, maj, or major stands for major-major (e.g. CM7 means CM/M7),
   • m, min, or minor stands for minor-minor (e.g. Cm7 means Cm/m7),
   • +, aug, or augmented stands for augmented-minor (e.g. C+7 means C+/m7),
   • o, dim, or diminished stands for diminished-diminished (e.g. Co7 means Co/o7),
   • ø, or half-diminished stands for diminished-minor (e.g. Cø7 means Co/m7).

   Other specific rules for extended and added tone chords are given below.