There are three main kinds of 7 chords –

Dominant 7 – usually just “7”

Major 7, and

Minor 7

Dominant 7 is the most common, but also the most complicated to explain, so we’ll start with the other 2!

But first, a little chord theory.

All the major and minor chords you find are made up of three different notes – these chords are known as triads.

The C major chord (or just C as it’s usually known) is made up of the

1st, 3rd and 5th notes of the C major scale.

The C major scale is:

C D E F G A B C

To qualify as a C chord, the chord needs to contain at least one of each of the notes

C  E  and  G

C major on the guitar:

An E chord comes from the 1st, 3rd and 5th of the E major scale:

Here’s E…

…containing 3 x E; 2 x B and 1 x G sharp

And so, we move on to the major 7 chords…

Going back to the C major scale, if you then add the seventh note of this scale to the first, third and fifth and you get a C major 7 chord, or Cmaj7:

I’ve added a B note to the chord. Practically speaking, you need to lose one of the existing notes of the chord in order to do this.  In this case, this is done by taking the first finger off. You lose a C and gain a B.

Minor 7 chords work in a similar way to major 7…

The same rules apply with minor 7 chords.

The minor chord is made up of the first, third and fifth notes of the corresponding minor scale (natural minor, to be exact – as corresponds to the key signature).

Add the seventh note of the scale and you get a minor 7 chord (or m7)

Dm scale

D E F G A Bb C D

Dm chord consisting of D, F and A notes:

Add the seventh note, which is C.  This is done by losing one of the D notes – now we have Dminor7:

And now, for complicated stuff…

Finally, dominant 7 (or just plain 7 chords)

The term dominant comes from another way of describing the degrees of a scale:

See below – the first column shows the notes of the example scale of G major; the second shows the degrees as numbers and the third uses terms that not many people use (especially outside classical music):

Now then, in the key of G, D is the dominant.  From that dominant note, we can work out the Ddominant7 chord.

To explain the next bit, I’ll extend the G scale to 2 octaves:

The notes of the G major scale across 2 octaves in the first row of the table above

The numbers from 1-15 of all notes in the next row, and…

In the next row, the numbers 1-8 counting from that dominant note.

If we take 1,3,5 and 7, with D as the starting point, we get a D  dominant7 chord!  Counting from the dominant, gives us the dominant chord.

Make sense? Does it seem unnecessarily complicated to you?  Well, music notation is full of these little idiosyncrasies, which is why so many people avoid it.  All the changes in musical styles over the centuries have contributed to the confusion – bits and pieces of rules have been kept, other rules discarded, and others have just become a bit frayed at the edges.

10 + 7 =