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Connecticut Shoreline Studio for Music Lessons
in Voice, Piano, & the Fundamentals of Music

Clef Notes

How to Use the Circle of Fifths to Identify Key Signatures

How to Use the Circle of Fifths to Identify Key Signatures

This is the fourth and final post in a series on How to Identify the 15 Key Signatures.

In order for this to be helpful, you will need to have read the first three posts:

Draw the Circle (Rhombus) of Fifths

If you’ve been following along, you should now be able to draw what we’re calling the Rhombus of Fifths in a just a few moments. It should look like this:

Circle-of-Fifths

Now you’re ready to start using it to help you identify key signatures.

How to Find the Key Signature in a Piece of Music

At the beginning of any written piece of music, you should find the key signature between the clef and the time signature.

There are three kinds of clefs: G, F, and C, and they look like this:

G, F, and C Clefs

Following the clef will be the time signature. There are many, many different time signatures, but here are a few common ones:

Time Signatures

In between the clef and time signature, there will often be a series of sharps and flats. This is what you are looking for. Here are a few examples:

Key Signatures

The Key of C Major Has No Sharps or Flats

If a piece is in the key of C major, there will be no sharps or flats in between the clef and the time signature. It will look like this:

Key Signature for C Major

Is It a Sharp Key or a Flat Key?

Key signatures are made up entirely of sharps or entirely of flats. There is no mixing of sharps or flats. So if a key signature is made up of sharps, it is considered a sharp key. If a key signature is made up of flats, it is considered a flat key.

Fifths Going Up From C Are Used to Identify the Sharp Keys

Remember the following sequence of fifths going up?

C  G  D  A  E  B  F♯ C♯?

These are the names of the sharp keys.

Fifths Going Down From C Are Used to Identify the Flat Keys

Remember the following sequence of fifths going down?

C  F  B♭ E♭  A♭  D♭  G♭  C♭

These are the names of the flat keys.

Count the Sharps or Flats

Let’s say you’re looking at this key signature:

Key Signature for F Sharp Major

You might have to pay careful attention, but you should be able to count six sharps. Keep that number in mind.

Get Out Your Circle of Fifths & Count Around to the Appropriate Hour

For sharps, the circle works like a clock. The key of G is at the one o’clock position, so it has one sharp. The key of D is at the two o’clock position, so it has two sharps, and so on. 

Since our key signature has six sharps, we need to know what sharp key is at the six o’clock position. If you drew your Circle of Fifths properly, you should find two notes named at the six o’clock hour: F♯ and G♭. Since F♯ is the note you added on your way clockwise around the circle (and up by fifths), that will be the name of the key with six sharps.

Let’s Identify a Flat Key

Let’s say this is the key signature you are identifying:

Key Signature for A Flat

For flats, think of the clock in a reverse manner with the fifths down going from one o’clock to seven o’clock only going counter clockwise.

Since this key signature has four flats, you should find yourself at A♭.

Voilá! Now you can identify all the major key signatures!

We will discuss minor keys and mode identification at a later date.

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