Ukulele Chord Theory

Keys of a Song
Music is written in a key. This key might change in the song to add some interesting movement or emotional emphasis. It is therefore useful to understand how they work so that you can choose the right chords in a song and transpose music from a tricky key into something you might prefer to play like C or G.

Characteristic of a Key
Each key is made up of a minor or major scale. They contain all the letters, A to G, of the scale. Examples:

C Major  C  D  E  F  G  A  B  C
G Major  G  A  B  C  D  E  F# G
B Major  B  C# D# E  F# G# A# B
F Major  F  G  A  Bb C  D  E  F

b = Flat - It is a note dropped down by a semitone
# = Sharp - It is a note raised up by a semitone.

All the keys except for A minor and C major use sharps or flats - Remember the black keys on the piano? The piano keyboard was designed to be biased towards the C Major scale so that you could play a key with just the white piano keys.

How do you know what, if any, are the sharps/flats?
All the tones are separated by what is called a semitone and two semitones is called a tone. If you look C Major and count the white keys, they are spaced from low to high as C +Tone +Tone + Semitone +Tone +Tone +Tone +Semitone. To get from E to F and B to C semitones were used, whereas all the other increments had to skip past a black note and therefore increased by a whole tone. All the major keys (even the flat or sharp major keys) will use this same pattern of semitones and tones. So with this information, you can check my scales above with the keyboard diagram below to see if I'm correct.

Enharmonic – Is it a Flat or Sharp?
If you look at the F major scale above why is it a “Bb” instead of a “A#”? Well that tone can be called either as they are essentially the same note. However in a scale, it is standard convention to include all the letters A to G and therefore Bb is the correct name choice (otherwise the scale would go from A to A# and miss B altogether). A# and Bb are said to be “enharmonically” the same.

Chord Spelling
The notes in a scale are numbered 1 – 8

1  2  3  4  5  6  7  8(1)
C  D  E  F  G  A  B  C

The chord name is always based on the first note in the chord. A standard major chord is a triad which means it is based on 3 different tones.
A major triad chord is made up of the root note (1), a 3rd (3), and a 5th (5).  For the chord of C major you have this:

1     3     5
C  D  E  F  G  A  B  C
Chord of C Major = C E G

It is useful to know what when you play the standard chord of C Major on the Ukulele, you’re actually playing 1, 3, 5 & 8. So it includes the higher C from the 3rd fret of the A string. Not all standard chords do this. The F major chord is F A C and when you play the standard F chord on the uke, it actually has two “A”s in it produced from the top and bottom string (See the red chord shape on the diagram). If you wanted to play F major as a full octave you could use the 5,5,5,8 chord shape shown in blue (this is the same chord "shape" as C Major but just moved down a few frets).

What is a 3rd and 5th?
Remember that each note on a keyboard or fretboard is a “semitone” apart. E.g. from C to C# or from E to F is a semitone. It is useful to understand what a semitone is because each fret position on the ukulele is a semitone apart.

As well as being the 3rd note in a major scale, a 3rd is also 4 semitones above the root note. A 5th is 7 semitones above the root or 3 semitones above the 3rd. So to get from C to E on a uke you could move up the fret board by 4 frets. On the keyboard you would skip past 4 of the black and white keys. If you look at the scale of B major above you could see that the chord of B Major would be:  B  D#  F#
D# is predictably 4 semitones above B and F# is 3 semitones above D#.

Chord Types - Vocabulary
  • The chord of C has the full name C Major but the “Major” tends to get dropped as C implicitly means C-Major.
  • Minor chords are always denoted with some sort of suffix like “m”, “min” or “minor”. Minor always uses a lower case “m” to avoid confusion with the “M” for Major.
  • 7th chords are always “Dominant” (which I’ll explain later). The “dominant” bit is usually dropped because a 7th chord by default is always dominant unless explicitly stated otherwise.
  • Major 7th chords are different to dominant 7th chords and always have a “M”, “Maj” or “Major” prefix.

Chord Types – Spelling
Here are the chord spellings for a range of chord types:

Major:        1 3 5
Minor:        1 b3 5
Diminished:   1 b3 b5
Suspended4:   1 4 5
Suspended2:   1 2 5
Dominant 7th: 1 3 5 b7
Major 6th:    1 3 5 6
Minor 6th:    1 b3 5 6
Major 7th:    1 3 5 7
Add 9th:      1 3 5 9
Major 9th:    1 3 5 7 9 (See note)
9th:          1 3 5 b7 9 (See note)
Minor 6th:    1 b3 5 6
Minor 7th:    1 b3 5 b7*
Augmented:    1 3 #5

Note:  You don’t have 5 strings on a uke in order to play any of the 9th chords. So you could try leaving out the root note or playing the Add 9th chord instead.
[correction best leave out the root or the 5th because these are the most dominant and therefore common to the key]

Minor Chords
What you notice quickly is the difference between a major and minor chord. The 2nd note in the chord is a flat 3rd (also known as a minor 3rd). This means it is 3 semitones above the root note instead of 4. The 3rd note is still a full 5th degree scale interval or 7 semitones above the root. However, this time it is 4 semitones above the 2nd note in the chord.

Example of C minor = C  Eb  G

This means you could say that a:
  • Major chord is made from a Root + 4 semitones + 3 semitones
  • Minor chord is made from a Root + 3 semitones + 4 semitones
And therefore
  • Major chord is made from a Root + Major 3rd + Minor 3rd
  • Minor chord is made from a Root + Minor 3rd + Major 3rd

7th chords
Any chord that has more than 4 notes is called an extended chord. You can go on forever adding minor and major 3rds. Extended chords tend to add a bit more emotion and movement to a tune. However in between a triad and extended chord you have the 7th chords comprising of 4 notes.
As you can see from the chord spelling above a 7th chord (dominant 7th) is a Major chord with an added minor 3rd. So if you look at the example of C7 below, you can see it has the 7th note in the scale interval flattened to Bb.

Because of the Bb, this chord does get played commonly in the key of F Major.
Whereas CMaj7 looks like this:

CMaj7 is in the key of C as none of the black keys are played. When you play it, it creates an interesting sound like it is asking you to play further chords that resolve the expression it is making. Try playing the chords of CMaj7, G and finally C in order and you’ll see what I mean.

The example above of C7 being a common chord found in the key of F Major is no accident. Very often the 5th degree chord in any key may be played as a Dominant 7th chord. The added 4th note in this chord remains within the key your playing. The 5th degree chord in any key is also known as the dominant chord in that key. If you were going to choose to play a tune using just 2 chords you would likely use the root chord (I) and the dominant chord (V). That is why when you first learn the Uke you learn the "C", "G" and "G7" chords right at the start (G is the dominant or fifth degree chord in C-Major). If you want to understand why the 5th is dominant, please read my Ukulele Harmony Theory page.

Triad Chords in a Key
Now we know what a major and minor chord is, let’s see what chords belong to each key. As C major on a keyboard is easy to understand let’s see what those white keys want to do.
Look at chord number 2 which is the 2nd degree chord in C major.

It starts with a D so we know the chord is called a D something. It also has F & A. If you count the semitones to F & A, you’ll see that:
  • F is 3 semitones above D which is a flat 3rd (or minor 3rd)
  • A is 4 semitones above F which is 3rd (or major 3rd)

By looking at my chord spelling section you’ll see that this chord must be called D minor.
Now have a look at Chord 7 which is the 7th degree chord in the key of C Major.
It is made up of B  D  F. If you count the semitones to D & F, you’ll see that:
  • D is 3 semitones above B, which is a flat 3rd (or minor 3rd)
  • F is 3 semitones above D, which is a flat 3rd (or minor 3rd)
By looking at my chord spelling section you’ll see that this chord must be called B Diminished (Bdim). Diminished chords are used a lot less commonly than the other chords in a key. They tend to create a particular emotional feeling that isn’t always wanted. However when used properly are very effective. For example in the song Bright Eyes from Watership Down do you remember the bit that goes, “Wooah Wooah is it a dream”. In the key I play this in, the two wooahs are a progression from Gdim to GMajor which is followed by CMajor and then finally a reduced (power chord) version of G which only has G & D in it (0,2,3,x in tab notation). Try and it and you’ll see what I mean. The reason why the diminished chord is unsettling is because it uses the 7th and 1st notes in the scale which are the least harmonious in that key. See my other theory page that explains this.

Anyway, back to the point....
If you work out the rest in the same way you’ll see that you end up with:

C  Dm  Em  F  G  Am  Bdim

This is the pattern for all keys. I have used Roman numbers here show where these chords sit within the C Major key. This use of Roman numerals is standard.

You can also write this as:

I  ii  iii IV V  vi  vii°

The use of the degree symbol and the upper and lower cases denote weather it is major, minor or diminished. You can now apply this pattern to any major scale to find the chords in that Key.

You will notice that I have included the minor scales here too. C Major is “enharmonically” equivalent to Am. I haven't included all the keys in this table but remember you can also have the scales of all the flats and sharps too. However, most songs tend to be written in a natural key.

It should also be noted (and remembered from the 7th Chord section above) that the 5th degree chord in a key is often played as a 7th. E.g. In the Key of C, G7 may often appear. Likewise in the key of G, D7 may appear.

What Key is a Song In?
Have a look at the chords and see which keys they seem to fit with the chords. This should narrow it down. Songs then often end with the root chord as it resolves the movement nicely. So if a song ends in C Major, the key was probably in C.

Transposing the Key
Once you know what key the song is in you can use my table above to shift all the chords up or down into another key. If you have a strange chord you don't understand, then simply count the semitones each note needs to be shifted by and see what you end up with - It should be correct. You might find that it doesn't sound relatively accurate when you play it. This could be because you may need to find an alternative chord shape for the chord you're trying to play such as the example I illustrated with F Major above.