Understanding Chord Symbols for 7th Chords

Review: Parts of a Chord Symbol

Chord symbols can include up to five parts. Each part is color coded for easier identification.

1. Note Name The name of the root of the chord. All chord symbols include the note name.
2. Modifier Describes the type of triad if it is not major. No modifier means the chord is major. Common modifiers are: m or - = minor, dim or o = diminished, aug or + = augmented.
3. Extensions Notes added to the triad by stacking 3rds to make more complex chords. The number represents the interval from the root of the triad to the highest extension. The most common extension is 7 which represents a 7th chord. 7th chord extensions are assumed to be minor 7 unless otherwise noted. We will study 7th chords in a later level.
4. Alterations Changes to the typical triad structure, such as suspensions or notes that are raised or lowered or added. The most common extensions are: sus = suspended 3rd, ♭5 = flatten the 5th of the triad, add9 = add a 9th to the triad.
5. Bass if the bottom note of the chord is not the root of the chord, a forward slash followed by the note name of the bass will be added at the end.

For more review on Chord Symbols see Understanding Chord Symbols.

7th Chords Written As Chord Symbols

Foundational Rule: 7th chord extensions are assumed to be a minor 7 unless otherwise noted.

• A Major 7 chord (also called a Major-Major 7th Chord) is a major triad with a major 7th. Because the 7th is major (not minor as in the foundational rule above) you need to add a capital "M" or "Maj" before the 7.
  Example: CM7 or CMaj7
• A Dominant 7 chord (also called a Major-Minor 7th Chord) is a major triad with a minor 7th. Because the 7th is minor you should not add anything before the 7.
  Example: C7
• A Minor 7 chord (also called a Minor-Minor 7th Chord) is a minor triad with a minor 7th. Because the 7th is minor you should not add anything before the 7 other than the "m" that is already present from the minor triad.
  Example: Cm7
• A Half-Diminished 7 chord (also called a Diminished-Minor 7th Chord) is a diminished triad with a minor 7th. This 7th chord symbol is very unusual and you may need to memorize it. The reason it is unusual is because there is no chord symbol for half-diminished. A diminished triad uses the symbol ^o. But the ^o7 symbol is used to represent the fully-diminished 7 (see below). Instead, the Half-Diminished 7 chord is represented by a m7♭5. What this chord symbol is saying is to build a minor triad, add a 7 and then flat the 5th. If you think about it for minute, you will see that this will create a half-diminished 7 chord. Yes, it is a strange way to label the chord, but that is what has become the standard symbol for it.
  Example: Cm7♭5
• A Diminished 7 chord (also called a Diminished-Diminished 7th Chord) is a diminished triad with a diminished 7th. Even though the 7th is diminished, the "^o" is already present from the diminished triad modifier. So you do not need to add a modifier before the 7 because it is already present from the diminished triad..
  Example: C^o7

Chord Symbols for Inverted 7th Chords

Inverted 7th Chords use Chord/Bass notation just like with triad inversions. Write the correct chord symbol followed by a forward slash and then the bass note.

To review chord symbols for triad inversions see Understanding Chord/Bass Symbols.

How to Identify a 7th Chord Using Chord Symbols

1. Stack the notes of the triad in 3rds to determine the root position triad. In the above example we move the top note down an octave to place it in root position.
     
2. The Note Name of the symbol will be the root of the chord. In the above example, the root is B. (Remember: the root of a chord is the lowest note when the chord is in root position.)
3. If the chord is not a major chord, add the correct Modifier. In the above example the triad is diminished so the modifier is ^o or dim.
4. Add the Extension. In this case the extension is a minor 7th. According to our Foundational Rule, a minor 7th does not need any modifier before it. But, watch out! Remember that a half-diminished 7 chord (diminished triad with a minor 7th) has the unusual chord symbol of m7♭5.
5. If the chord is not in root position, add a forward slash and the name of the Bass. In the original example (before we stacked it in thirds) the bass was a D so the full chord symbol is Bm7♭5/D.

How to Notate a 7th Chord from a Chord Symbol

Build an Fm7/C triad.

1. Build the triad using the Note Name as the root. In the above example the note name is F so the root of the triad is F.
  
2. Add the 3rd, 5th and 7th of the chord by stacking thirds above the root. We do that below by adding an A, C and E above the F.
     
3. Make sure the triad is the correct quality (major, minor, diminished, or augmented) based on the Modifier. Remember: no modifier means the triad is major. In this example the modifier is minor, so we need to add a flat to the A to create a minor triad.
      
4. Make sure the 7th is the correct quality (major, minor, or diminished) based on whether it has a modifier. Remember: no modifier means the 7th is minor. In this example the triad is minor and so the 7th is also assumed to be minor. So we need to add a flat to the E to create a minor 7th.
       
5. Place the correct note in the bass. The note name following the forward slash should be the lowest sounding note (bass). In this example the bass in the chord symbol is a C, so we need to move the C down an octave so that it is the lowest sounding note.
           
   Remember: it is not necessary to place the triad in close position unless you wish to do so. All that matters is that the correct note is in the bass.

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