The failsafe method of working out which chords fit a key

You know the scenario, you’re either trying to remember the chords for a song that you don’t have music for, or you’re trying to find some chords to accompany a new melody, so you stab at all sorts – G F, C Em, A, Bb – some seem to work but some don’t. There is, however, a method of narrowing down the options to just seven chords – you just need to know what key the song is in.

Each major scale is made up of seven notes so the scale of C major is made up of C D E F G A B. Other scales will have sharps or flats instead of some of those notes. In addition to the notes in the major scale or key, there are also seven chords that fit over the individual notes.

The chords are either major or minor in sound and all follow the same major/minororder sequence:

Major Minor Minor Major Major Minor Minor (actually ½ diminished but a minor will work fine)

So the chords in the key of C are:

C Dm Em F G Am Bm (or Bdim)

So if your song is in C, these are the chords that you will need. Some chords are more common than others – generally the root (C), the 4th (F), 5th (G) and 6th (Am).

You can apply this formula to every major key so songs in D would have the following chords:

D Em F#m, G A Bm, C#m

If you’d like to read more, including how to work out which sharps and flats are in which keys, download the free article Playing By Ear on our Members section in the Store – you’ll need to register first.