How do I find the key of a song?
Finding out the key of a song is actually very simple. With a few tricks, you can even figure it out without 10 years of studying music.
What is a key?
In music, we have 12 keys. You can think of each key as a kind of ‘bubble’ that contains 7 chords. So: 1 key = 7 chords.
C major key
A listing of the C major key is here:
Scale degrees are always marked with Roman numerals.
All the chords mentioned above are allowed in the C major key. There are many songs, very often also in jazz, which contain chords that are not included in the key. We already looked at a variation of this topic in the Harmonic Analysis.
The Circle of Fifths
Now we have 11 other keys. We see all of these keys in the circle of fifths.
Here is the circle of fifths written out non-visually:
Analyzing Songs
Here are two examples of keys in songs:
Here is a song that starts with zero accidentals. In the circle of fifths or also in the table, we see that no accidentals means either C major or A minor. Whether it is one or the other, we will look at it in a moment.
Here we have an example of a song that has two sharps. So we either have D major or B minor here.
As a last example, we have one accidental, but this time a b instead of a #. This song must therefore be either in F major or in D minor.
This can go on up to 7 sharps or 7 flats.
Is the song in major or minor?
To find out whether the song was written in a major or minor key, we first need to clarify that both keys (the major as well as the parallel minor key) contain the exact same chords. So no matter if you end up writing C major or A minor, it is sonically correct. However, it is theoretically not correct if you say C major, but the song is in A minor.
Let’s look at a beginner song:
The song, Oh My Darling Clementine has one sharp. This means that the song is either in G major or E minor. It starts with G major and also ends with it. Therefore, the chance is very high that the song is in G major.
It cannot be C major, F major or any other key, because we have a sharp at the beginning of the song. So according to the circle of fifths, it must be either in G major or E minor.
In the next example, Drunken Sailor, we have no accidentals. Thus, we move between C major or A minor. This song begins and ends with A minor. The stars are good that this song is in the key of A minor.
I personally always play it safe by listening to the sound. If you play the whole song through without the last chord, you expect a final closing chord. This last chord, which everyone expects, is called ‘tonic’. The tonic is the first chord of the key and you also end with it.
As always, there are these great exceptions. There are also songs that never end, or have a so-called open ending with a minor major 7 chord. In this post we are talking about the rule, not the exceptions.
Audio Examples
In the first example, I play a chord progression in C major. However, I do not end it with the C major chord.
Audio Example
C, Am, F, G
Sounds kind of unfinished, doesn’t it?
In the second example, I play the exact same progression, but this time with the C major chord at the end to finish it off.
Audio Example
C, Am, F, G, C
Sounds kind of like the end, right?
Here is another example with an open C minor major 7 ending. Actually, it is finished but actually not. Listen for yourself:
Audio Example
C, Am, F, G, CmMaj7
Somehow it’s finished, but somehow it’s not.
What do I get out of knowing the key?
Of course, it is very useful to know the key and the associated chords of a song. On the one hand, you know pretty quickly what will come at you. On the other hand, you know which scales you can use to improvise.
For example, the pentatonic scale can be played on the parallel minor key. So if the song is in C major (or A minor), you can improvise on the minor key (in this case A minor) with the pentatonic scale.
