How To Work Out Any Major Key
In this lesson I will show you how to work out every major key in music in a number of different ways. Sometimes you will need to work out the key from written notation. Other times you may only have a chord chart to work from. This lesson aims to give you a variety of methods to help you figure out any major key. I will also be writing about at how to work out minor keys at some point in the future. Stay tuned!
This lesson builds on the a previous lesson where I define what a key is and introduce the major scale formula. If you haven’t already completed this lesson then I suggest you take a look at it here before continuing. It is also highly recommended that you complete the keys worksheet in that lesson so that you have something to work from! For convenience I’ve put a link to the worksheet at the bottom of this page. I’ve also included a quick information sheet with the ver basic concepts covered in that lesson.
METHOD 1 – Key Signature
Working out the key of a piece of music written in standard notation is straight forward.
Keys Containing Sharps
Look at the final sharp in the key signature. The note above the last sharp is the root of the major key. For example. If the last sharp in the key signature is C#, the key is D major. The key is always a semitone above the last sharp in the key signature.
Keys Containing Flats
Count back 4 notes from the last flat. If the last flat in the key signature is Eb, count back four notes. Counting back four notes from Eb means you land on Bb, which is the root note of the major key.
Another method is to Find the penultimate flat in the key signature. For example, if the key signature contains the flats Bb, Eb and Ab, the key is Eb major.
Keys Containing No Sharps or Flats
The only major key containing no sharps or flats is C Major.
METHOD 2 – Mnemonic
Mnemonics can help you to remember the order of sharps and flats. Knowing this in combination with the first method of working out keys will help you to work out any major key.
Order of Sharps
| Father | Charles | Goes | Down | And | Ends | Battle |
Order of Flats
| Battle | Ends | And | Down | Goes | Father | Charles |
If a piece of music is written in a major key and contains a G#, any Fs or Cs will also be sharpened to make them F#s and C#s. This is because the sharps work on an accumulation basis. It is not possible to have a major key that contains G# but not F# or C#. Both of these notes will also be sharpened to achieve the correct formula as described in a previous lesson. You can test this theory by working every key on the worksheet available to download at the bottom of this lesson.
The same concept applies to flats too.
Therefore in order to work out the key, find the right most sharp/flat in the piece of music from the mnemonic above. Once you’ve found the right most sharp/flat, apply the same process as method 1 described above in this lesson.
METHOD 3 – Harmonic Progression (Chords)
Just as a key has a set formula, the chords in any given key also follow a set pattern. This is because the chords are defined by the notes in the key. The reasons and theory behind this will be discussed in a future lesson. For now though, here is the order of chord types in every major key. Chord numbers are depicted by roman numerals:
| I | II | III | IV | V | VI | VII |
| Major | Minor | Minor | Major | Major | Minor | Half Diminished |
Because the structure of chord types remains the same in every key, it is possible to work out the key of a piece of music by looking at the chords. This is because the major, minor and half diminished chord will always be in the same position in every key. I.e. chord I is always major, chord II is always minor etc.
Let’s analyse the following harmonic progression and work out what key it’s in:
| | | G | | | Em | | | C | | | D | | |
There are a few clues which help us to figure out what key this harmonic progression is in.
- The C natural tells us that it cannot be written in a key with more than one sharp, because C# is the second sharp in the sequence of sharps (see mnemonic method above).
- The E natural tells us that it cannot be written in a key with more than one flat, because Eb is the second flat in the sequence of flats.
- There are 3 major chords in the harmonic progression; G, C and D. The only key that contains these 3 major chords is the key of G major.
- The Em chord would be chord VI in the key of G major. Chord VI of a major key is always a minor chord (see table above) so this would fit within the key of G major.
This method involves a little bit of working out, but it’s very helpful when working from chord charts in the absence of written notation.
You can apply a similar method to melodies to work out the key. Look at all of the notes and find the right most sharp/flat from the mnemonic series in this lesson. Once you’ve found the right most sharp/flat, you will have a good indication of what key the piece of music is in.
Ed, I am learning so much from your postings. Thank you for the well presented and informative tutorials. I have been playing about 6 years and always enjoy learning. Thank you.
Hi Ann,
I’m really pleased that you’re enjoying reading these lessons. I have some more coming up soon so please do bookmark our lessons page and check back again soon.
All the best,
Ed