What are keys? What key am I in? Try the circle of fifths!

A key is just another way of saying what scale you’re using. If your song is based on the C major scale, it’s in the key of C major. But for every major scale, there’s a relative minor with the same notes, so what’s stopping the song being in the key of A minor? The difference is that in C major, C feels like the ‘home’ note or chord – called the ‘ tonal centre’. The song will likely begin and end on this note/chord, and will return to it at the start of sections. A song in A minor will likewise build outwards and return to Am. These ‘rules’ are often broken, mind you.

Changing key mid-song can re-energise things or flip into an unexpected new part. This can be accomplished by taking a section, duplicating it, and transposing the copy. A one semitone shift in either direction, for example.

For a more considered approach, we can move to a destination key that shares notes with the current one. For C major, the most similar keys/scales would be G major (uses F# Bb/A#

instead of F), and F major ( instead of B). From C up to G is an ascending perfect fifth, and from C down to F a descending perfect fifth. Interesting! In fact, to find the ‘closest’ two scales to any major or minor scale, just go up or down a perfect fifth.

This results in the Circle of Fifths, a superb songwriting tool, which is shown in our diagram. Adjacent keys are most similar, and the further around the circle you go, the more disparate and unrelated they become. So, for C major, good choices for a key change would be F and G (+/- 7 semitones, a perfect fifth away), and going one more step in each direction, D

Bb/A# and (+/- 2 semitones, a major second).

To transition from a major to minor key, or vice versa, we just use the relative minor/major relationship – minor keys are shown on the inside of the wheel. For more, see 221’s Easy Guide on the Circle of Fifths.