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What are 7th chords?

When learning guitar, the first chords you are likely to encounter are major and minor triads, chords that consist of three notes. But what chords should you learn next? Usually, the answer is 7th chords.

But what are 7th chords exactly?

If you are looking for a quick overview: 7th chords are triads with an additional 7th interval (from the root) added, making it a 4 note chord (Tetrad). The most common on guitar is the dominant 7th (aka major minor 7th chord) a major triad with an added minor 7th interval (10 semitones from the root). Other common 7th chords include the major 7th, minor 7th, minor 7 flat 5, and diminished 7th.

In the following article, we’re going to take a closer look at 7th chords, some useful shapes you can use to play them, and how to incorporate them into your own music.

This article is part of a larger series on 7th chords and includes the following articles:

How 7th chords are written

One confusing aspect of 7th chords is how they are written.

For example, an Amaj7 chord should be read as an A + a major 7th interval, not an A major chord with a 7th. The ‘A’ doesn’t require ‘maj’ to be written, it is implied as it is not indicated as minor (min), augmented (aug), or diminished (dim).

On the other hand, if there is no prefix in front of the 7 as is the case with a dominant 7th chord, usually written as C7 you can assume the 7th is a minor 7th interval (spanning 10 semitones from the root).

So, in the case of C7, we know the C is major with a minor 7th interval added, making C7 a dominant 7th chord aka a major minor 7th chord.

Another example of this is the minor 7th chord, usually written Cmin7. In this instance, the chord is a C minor triad with a minor 7th interval added, giving us Cmin7. If minor was not written it would be implied that the note letter name is major, and as we now know the 7 is considered minor unless indicated otherwise.

So, keep in mind when looking at 7th chords, if you see major written after the note letter this will always refer to the added 7th interval. If you see minor, diminished, or augmented it will apply to the note letter name.


What do 7th chords sound like?

While we’ll be discussing five different 7th chord variations, and most of these sounds very different from one another, but as a general rule 7th chords are more dissonant than triads.
While triads sound consonant (in agreement harmonically) the additional pitch added to the triad structure to form a 7th chord, makes the chord richer harmonically and less in harmonic agreement.

C7

The blend of major and minor, and the tritone (3 whole steps) between the 3rd and 7th creates dissonance and is responsible for the signature bluesy sound.

Cmaj7

Major 7th chords sound very open, and reminiscent of Jazz.

Cmin7

Minor 7 chords sound similar to major 7 chords but as you might expect from a minor chord sound more melancholy.

C7b5 (C half diminished)

Half-diminished 7th chords are tense and unstable. They are often used as passing chords before the V chord (aka they are often used as the predominant chord) in a chord progression.

Cdim7

Diminished 7th chords sound even tenser than half-diminished 7th chords and as a result, are often used as the dominant chord before resolving to the tonic chord.


How are 7th chords constructed?

As we now know, 7th chords are built on top of triads (i.e. major or minor triads) with an additional 7th interval from the root.

I’ve included the chord name, symbol, and scale degree formulas for each of the common 7th chords below, however, we’ll go over each in more detail in the following section.

ChordChord SymbolScale Degree Formula
Dominant 7th
(Major/minor 7th)
7, dom71, 3, 5, b7
Major 7thmaj7, M71, 3, 5, 7
Minor 7thM7, min7, -71, b3, 5, b7
Half Diminished 7th
(minor 7 flat 5)
ø71, b3, b5, b7
Diminished 7th
dim7, o71, b3, b5, bb7

Another way to build 7th chords is by stacking thirds, meaning we skip every second note letter name, the same way we build triads.

For example, CMaj7 consists of a C, (skip the D), E, (skip the F), G, (skip the A), and B.

C major 7 stacked thirds

This gives us the intervals of a major third between the C and E and a minor third between the E and G, just as we would find in a major triad. The interval between the 3rd (G) and 4th (B) notes is also a third, in this case, a major third.

Why thirds?
If this is all new to you, you might be wondering why chords are built with thirds. Thirds are consonant intervals, meaning they are pleasing to the ear. While subjective, it’s generally accepted that the most consonant intervals are octave, perfect fifth, perfect fourth, and thirds (both major and minor), and of course, unison as they are the same note. Another reason thirds are used often in chord construction is how the notes are distributed within their accompanying scale. If you consider a typical heptatonic (7 note) scale such as the major scale, thirds sound pleasing to our ears as there is an equal distribution of the notes within a given scale that the chord is derived from.

With that out of the way, In the section below we’ll start looking at the construction of the most common 7th chords on the guitar, starting with the dominant 7th chord.


Dominant 7th chords

What are Dominant Chords?
When learning about 7th chords this is where we move from playing just minor and major chords to also include dominant chords. Dominant chords are major triads with a minor 7th added, hence why they are also called major minor chords. Dominant may also refer to the function of the chord within the chord scale e.g. the dominant chord, the V chord, is built on the 5th scale degree of a given key. For example, in the key of A major E is the dominant chord, which can be substituted with an E7 chord as dominant chords can be used as the V chord in major keys (often written as V7) and the VII chord in minor keys. Their function, usually, is to direct the music back to the tonic.

Because the dominant 7th chord is so common, it’s usually written simply as a 7 chord e.g. C7 although occasionally it is also written as Cd0m7. It is also referred to as a major minor 7th chord, which we discussed above.

All dominant 7th chords are major in quality due to the major third but the 4th note is a minor 7th from the root, giving the chord a mix of major and minor tonalities, as seen in our example C dominant 7th chord below.

C7 Intervals

If thinking in intervals a simpler way to identify the notes of a dominant 7th chord is to add a fourth note to a major triad a whole step below the root but in the next highest octave, for example, B♭ is a whole step below C.

If referring to this type of chord by scale degrees, the formula is: 1 – 3 – 5 – ♭7

123456♭7
CDEFGAB

As we can see in the example below, if compared to a C major chord we can simply add the flat 7 (B♭) by fretting the 3rd fret of the 3rd string to form a C7 chord (C dominant 7th).

C Major and C7 Chord Chart

If you need to brush up on reading chord charts click here.

You can read more about dominant 7th chords, including chord charts, and more information on how they are constructed here.


Major 7th Chords

Usually written as CM7 or Cmaj7

Major 7th chords are simply major triads with a major 7th interval (from the root) added. The major 7th interval is 11 semitones above the root, or one semitone below the root in the next highest octave, e.g. B is a half step (semitone) below C.

Major 7 Chord Intervals

The scale degree formula used is 1, 3, 5, 7

1234567
CDEFGAB

If building a Cmaj7 chord from C major we can lower the C to B by playing the 2nd string as an open string as the C (root) is already included on the 5th string.

C Major and Cmaj7 Chord Charts

You can read more about major 7th chords, including more information on how they are constructed here.


Minor 7th Chords

Usually written as Cmin7 or Cm7

If you know your triads, you have probably already worked out the difference between the major and minor 7th is the minor third and minor 7th intervals.

C minor 7 intervals

Alternatively, we can simply stack a minor third on top of our minor chord’s 5th interval.

If referring to scale degrees our formula is 1, ♭3, 5, ♭7

12♭3456♭7
CDEFGAB

If we’re building a Cmin7 chord from C major we can mute the 4th string and add our B♭ on the 3rd fret of the 3rd string.

We can then add the E♭ by moving from the 1st fret of the 2nd string to the 4th fret and as we still require a G to form a Cmin7 chord we can easily pick that up on the 1st string by fretting the 3rd fret.

C Major and C minor 7 Chord Charts

You can read more about minor 7th chords, including more information on how they are constructed here.


Half Diminished 7th (aka Minor 7 flat 5)

Half diminished 7th chords are also commonly referred to as minor 7 flat 5 chords. Taking this naming convention we can easily work out a half-diminished 7th chord is simply a minor 7th chord with a flattened 5th, making it diminished.

Why is it called half diminished?

A diminished triad is a chord formed by stacking two minor thirds e.g.

A Diminished Triad - Comprised of minor 3rd intervals

This means the perfect 5th has been flattened by a semitone. When a perfect interval (e.g. unison, fourth, fifth, or octave) is flattened by a semitone, it is diminished. A half-diminished 7th chord features a min7 interval above the root.

C Half Diminished Intervals

This results in the chord being comprised of a major third above our second minor third interval. We refer to this type of chord as half-diminished. If the third interval was also a minor third it would be a diminished 7th chord, denoted by two flat symbols.

If referring to scale degrees our formula is 1, ♭3, ♭5, ♭7

12♭34♭56♭7
CDEFGAB

If comparing the structure of a C Major chord to a C half-diminished 7th chord, we’ll need to move our E on the 2nd fret of the 4th string to G♭ on the 4th fret. We’ll then need to fret the 3rd string at the 3rd fret to grab our B♭ note and then move from the first fret of the 2nd string to the fourth fret to add E♭.

C Major and Cmin7♭5 Chord Charts

You can read more about half-diminished 7th chords, including more information on how they are constructed here.


Diminished 7th

Knowing the structure of our half-diminished 7th chord, the only difference from a diminished 7th chord is the minor 7th interval becomes a diminished 7th interval (°7) which is 9 semitones above the root, a minor 7th is 10 semitones.

Diminished 7th Chord Intervals

This means the chord is comprised of three stacked minor 3rds.

Our scale degree formula, in this case, is 1, ♭3, ♭5, ♭7

12♭34♭567
CDEFGAA

To form a Cdim7 chord we’re only moving the 7th note of the scale down a semitone if compared to the C half-diminished chord we formed above.

If starting from A major, however, we can slide up two frets (a whole step) on the 4th string to G♭ and fret the 2nd fret of the 3rd string to include the A. We can then move from the 1st fret on the 2nd string to include E♭. Lastly, as it can feel easier to play this chord shape when barring the 1,2, and 3 strings, we can include an additional G♭ on the 1st string.

C Major and Cdim7 Chord Charts

Using 7th chords – Moveable Shapes

Seeing an example of how to transition from major to variations of 7th chords in the open position is useful in helping understand the theory behind 7th chords, but not as practical as learning moveable barre chord shapes, as we can then take an existing shape and play 7th chords all over the neck.

I’ve included examples below using root 6 (anchored to the 6th string), root 5 (anchored to the 5th string), and a couple of examples of root 4 chords (anchored to the 4th string) for half-diminished and diminished chords, utilizing either a D or F shape.

One useful tip, at least when playing dominant and minor 7th chords is to simply remove the pinky from the fretboard if playing an E major shape for dominant chords and an A minor shape for minor chords.

Dominant 7 barre chord (root 6)

Starting with the dominant 7th chord, take an E major barre shape and remove the pinky from the 4th string. This adds the 7th to the 4th string.

G Major and G7 (root 6) Barre Chord Charts

Dominant 7 barre chord (root 5)

We can also do the same if anchored on the 5th string using an A major barre shape.

B Major and B7 (root 5) Barre Chord Charts

Major 7 barre chord (root 6)

To form a major 7 barre shape we simply need to lower by one fret our finger on the 4th string.
This requires a different grip however as the pinky normally frets the 4th string, and is blocked by the ring finger.

The simplest way to form the chord is to swap the pinky with the index finger, so the pinky is fretting the 5th string and move the index finger down one fret on the 4th string.

G Major and Gmin7 Barre Chord Charts

Major 7 barre chord (root 5)

If anchoring on the 5th string, we can simply lower the note played on the 3rd string by a fret, giving us a reverse open D shape on the 2,3, and 4th strings.

Use the middle finger for the 3rd string, ring for the 4th, and pinky for the 2nd string.

B Major and Bmaj7 (Root 5) Barre Chord Charts

Minor 7 barre chord (root 6)

A minor 7th barre chord is simple if you already know your E major barre shape. Simply lift the pinky and middle fingers off the fretboard completely.

G Major and Gmaj7 (Root 6) Barre Chrod Charts

Minor 7 barre chord (root 5)

The simplest way to play a minor 7th barre chord anchored to the A string is to start from a minor barre chord shape and lift the pinky.

B minor and Bmin7 (root 5) Barre Chord Charts

Half Diminished 7th chord (root 4)

Root 4 D shapes are usually a bit of a stretch (try the first example of an E major chord below) but when playing half-diminished 7th chords we simply bring the 3, 5, and 7 notes of the chord one fret higher than the root note on the 4th string.

E Major and Emin7b5 (root 4) Barre Chord Charts

Diminished 7th chord (root 5)

Lastly, to form a diminished 7th chord from a half-diminished 7th chord, we must lower the 7th located on the 2nd string down a fret so our diminished 7th chord is made up of stacked minor third intervals.

Emin♭5 and Edim7 (root 4) Barre Chord Charts

There’s any number of different voicings you can use to play moveable 7th chords, I’ve included additional shapes in the articles referenced at the beginning of this article that show each of the 5 7th chords discussed here in more detail.


When to play 7th chords (7th chord function)

Now that we know some useful moveable shapes, where do we play 7th chords?

Realistically, we can play a 7th chords wherever we like, provided they sound good. But in most cases, as 7th chords sound less stable they introduce tension which demands resolution.
the information below makes a good starting point.

Dominant 7th chord function

Dominant 7th chords are the most common 7th chords and are almost always played as the V chord, the dominant chord in major keys, and the VII chord in minor keys. As the dominant 7th chord isn’t fully compliant with major keys, due to the minor 7th interval, it sounds unstable and wants to resolve to the tonic chord.

Major 7th chord function

Major 7th chords can be played in place of major chords, meaning we can play them as I and IV chords in major keys and III and VI chords in minor keys. Major 7 chords sound jazzy and open.

Minor 7th chord function

Minor 7th chords can replace minor chords. This allows us to play minor 7th chords as the ii, iii, and vi chords in major keys and the i, iv, and v chords in minor keys. They sound similar to major 7th chords in many ways but as you would expect from a minor chord, sound more melancholy.

Half diminished 7th chord function

Half-diminished 7th chords are dissonant, and unusual on their own but add tension that is then released when moving to another chord.

Diminished 7th chords function

Diminished 7th chords are also commonly used as passing chords, resolving to major or minor chords a half step higher in pitch.


Summary

7th chords are the ideal place to begin building upon your existing chord theory and when incorporated into your own playing bring additional nuance to chord progressions compared to triads, allowing for greater expression when writing music. I hope the information above serves as a useful introduction to 7th chords in all their glory.

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About Marty

My name's Marty, I've been into guitars for over 30 years. Theacousticguitarist.com is my blog where I write about acoustic guitars, music, and home recording.