Music Theory: Keys, Scales and Triads

The table below summarises the basic ideas of music theory that relate to keys, key signatures, scales and triads. The key signature, major triad, minor triad and degrees of the scale are listed for all of the common major keys. Just find the key that you want to look up in the left hand column, then read across to find the triads, key signature etc.

Note that some degrees of the scale (e.g 2nd & 9th) correspond to the same note. The difference is that one (in this case, the 2nd) will be a note within the first octave of the scale, and the other (the 9th) will be in the second octave of the scale.

Thanks to Laramie Sasseville for getting me started with this reference table.

Major Key	Key Signature	Major Triad	Minor Triad	1^st	2^nd 9^th	3^rd 10^th	4^th 11^th	5^th	6^th 13^th	7^th	Octave
C		C E G	C Eb G	C	D	E	F	G	A	B	C
Db	b b b b b	Db F Ab	Db Fb Ab	Db	Eb	F	Gb	Ab	Bb	C	Db
D	# #	D F# A	D F A	D	E	F#	G	A	B	C#	D
Eb	b b b	Eb G Bb	Eb Gb Bb	Eb	F	G	Ab	Bb	C	D	Eb
E	# # # #	E G# B	E G B	E	F#	G#	A	B	C#	D#	E
F	b	F A C	F Ab C	F	G	A	Bb	C	D	E	F
F#	# # # # # #	F# A# C#	F# A C#	F#	G#	A#	B	C#	D#	E#	F#
Gb	b b b b b b	Gb Bb Db	Gb Bbb Db	Gb	Ab	Bb	Cb	Db	Eb	F	Gb
G	#	G B D	G Bb D	G	A	B	C	D	E	F#	G
Ab	b b b b	Ab C Eb	Ab Cb Eb	Ab	Bb	C	Db	Eb	F	G	Ab
A	# # #	A C# E	A C E	A	B	C#	D	E	F#	G#	A
Bb	b b	Bb D F	Bb Db F	Bb	C	D	Eb	F	G	A	Bb
B	# # # # #	B D# F#	B D F#	B	C#	D#	E	F#	G#	A#	B

Minor keys

The keys listed include all the most commonly used major keys. To find the key signature and notes of the scale for a minor key, use the second table to find the relative major key, then look up the key signature of the relative major key. For example, to find the key signature for B minor, find the relative major (D major) then find it's key signature (2 sharps). This means B minor also uses 2 sharps.

To find the notes of the scale for the minor key, look up the scale for the relative major key but start from the root of the minor scale (which will be the 6th of the major scale). In the above example, the scale of B minor is found by reading from the scale of the relative major (D major). Start on the 6th (B), then read across, looping back from the octave to the 2nd.. This gives us B C# D E F# G A as the B minor scale.

Enharmonic equivalents

Note that the key signature (and scale and triads) are not the same for F# and Gb major, even though these two notes are enharmonically equivalent, meaning they are played using the same key on a piano. You would play these two scales in exactly the same way on a piano, and they would sound the same, but the notes are still written down differently. So you would always write an F# major triad as F# A# C# and a Gb major triad as Gb Bb Db. This is true for all enharmonic equivalents, so a C# major scale is written differently from a Db major scale, and so on.

Also, it might seem a little odd to come across notes such as Fb, for example in a Db minor triad. Although you might be tempted to substitute E instead of Fb, as they are enharmonic equivalents, it is wrong to write a Db minor triad as Db E Ab - you must write the triad as Db Fb Ab.

Other keys

The table above lists the most common keys, but you might want to find out information about a key that is not listed (for example G# major). To work out the major scale or key signature for the more unusual keys, simply find the key with the same letter name (in this case, G major), then add the appropriate accidental (sharp or flat) to all notes in the scale. This often means that one of the notes becomes a double sharp (or double flat). In our case, to find the G# major scale, we find G major (G A B C D E F#) then add sharps, giving us G# major: G# A# B# C# D# E# F##.

The key signature of the "unusual" key will have seven more sharps or flats than the key with the same letter name. In our example, the key signature for G# major will have seven more sharps than G major. The table lists G major as having one sharp (F#) so G# major will have 8 sharps (F will be double sharp).

The idea of having double sharps or double flats is a little strange when you first come across it, but it's a well established idea in music theory and means you can use consistent rules for scales and keys.

Relative minor and relative major keys

Each major key has a special relationship with a particular minor key. When the two keys share the same key signature we say that one key is the relative minor (or relative major) of the other.

The table below shows the relationships between the major and minor keys. To find the relative major or minor for another key just look up the corresponding entry in the table. For example, to find the relative minor of D major, find D in the major key column - this gives you B minor in minor key column so B minor is the relative minor of D major.

Relative Major Key	Relative Minor Key
C	A minor
Db	Bb minor
D	B minor
Eb	C minor
E	C# minor
F	D minor
F#	D# minor
Gb	Eb minor
G	E minor
Ab	F minor
A	F# minor
Bb	G minor
B	G# minor

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Last updated October 2011