Music Theory - How to work out which sharps or flats are in any key

Music Theory - How to work out which sharps or flats are in any key

Sometimes an advancing guitarist will want to know what sharps or flats are in a key. And without a classical training, this can sometimes be hard. Here is an easy and foolproof method to know what notes are flat or sharp in any key, based on your knowledge of the fretboard.


Before you begin, this method presumes you know HOW to work out the notes on the fretboard. If you can’t do that yet, then this article is too advanced for you! Learn that first, and then come back to this article later.



1)First choose the key you want to find the notes for. Find the root note of the key on the Low E string

2)Play the Major Scale (also known as Ionian Mode) shape starting on that note, until you have played the first 8 notes of the scale. Here’s an example starting from the note A:










3)Now you can go ahead and work out the note names. In this case we have:


A B C# D E F# G#


So we now know that the key of A has 3 sharps.



Remember, there must be 1 of each letter name in every key. That’s how you know A has a C# and not a Db – because if it is Db, you have skipped the C letter name.


In Flat keys (like Db, Eb etc) all the accidentals are flat. In Sharp keys (like D#, F# etc) they are all sharp. In natural keys (like A, B, E etc) the accidentals are all sharps EXCEPT for the key of F, the odd one out. It has one flat – F G A Bb C D E



Let’s do another example, the key of Gb. You can find a Gb note on fret 2 of the Low E string:









The notes are: Gb Ab Bb Cb Db Eb F


Therefore, there are 6 flats in the key of Gb.


We could also call this the key of F#. These two keys are “enharmonic” which means they sound the same.


F# G# A# B C# D# E# The key of F# has 6 sharps.


It is not a coincidence that the Key of G has 1 sharp, and the Key of Gb has 6 flats.


Also, the key of F has 1 flat, whereas the key of F# has 6 sharps.


If you add the sharps (or flats) in any key, to the number of flats (or sharps) in the FLAT (or sharp) version of that key, you get 7!


In other words:


C has 0 sharps            C# has 7 sharps

C has 0 flats                Cb = 7 flats

D has 2 sharps            Db has 5 flats


E has 4 sharps            Eb has 3 flats



This works for all keys! If you aren’t sure whether this will ever be useful for you, the answer is it may not ever be. But if you ever want to write music for other instruments like saxophone, flute or trumpet, and write music in different keys, you will at some point need to know which flats and sharps are in each key.


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