Make sure you have printed out the circle of fifths diagram for reference.
The most common application of the circle of 5ths is to aid in the memorization of the note names in each key. Knowing the notes in each key is essential to being able to play, create, read, and improvise music on any instrument. A little work learning your keys will make a lot of other learning easier for you.
Each Major Key is Unique
In the major scale lesson I explained how the structure of the major scale is always constant. The major scale can be built off of any of music's 12 notes, therefore there are 12 major scales and 12 major keys.
While the structure is always the same, the specific notes in each major scale are different. Each major scale/major key has a unique set of notes.
In music we uniquely identify each major key by the number of sharp notes or flat notes it contains.
The circle of fifths and fourths logically orders the keys making it easy to learn how many sharps or flats occur in each key. In this lesson I'm going to show you how to memorize the number of sharps or flats in each major key using the circle of 5ths and 4ths. Each note on the circle will serve as the root note for a one of the 12 major scales.
The Key of C Major
The key of C major is the only major key with no sharps or flats. It only contains natural notes C, D, E, F, G, A, and B. That's why we start with C at the top of the circle.
Moving in 4ths on the Circle
To move in fourths around the circle we need to move counter-clockwise. You can find a perfect 4th on your bass on the same fret, next higher string. Another easy way to think of 4ths is by going up the major scale from the root to the 4th note. From C you’d go C, D, E, F. F is the 4th above C.
When you go up a fourth on the circle you arrive at the next key F major. (You can start on any F note on the fretboard.) The key of F major contains the notes F, G, A, Bb, C, D, and E. F major contains 1 flat the Bb. F is the only major key with 1 flat. Play it on your bass and spell out the note names.
To get to the next key, go up a 4th from F. That will bring you to the key of Bb major on the circle. Bb major contains 2 flats Bb and Eb. Bb major has the notes Bb, C, D, Eb, F, G, and A. Again, play the scale and spell it out.
The pattern is always the same: each time you move to the next key a 4th above, you add 1 flat. The same pattern continues all the way around the circle until there are no more notes left to flat. (In the key of Cb major, all 7 notes are flat.)
Moving in 5ths on the Circle
Going the opposite direction on the circle creates a similar pattern only now adding sharps.
Clockwise the keys move in 5ths. Again, if you know your intervals it is a perfect 5th above. Or, you may recognize the pattern from the root and fifth lesson. An easy way to find the fifth is to count up the notes of the major scale starting on the root. From the root C you’d go C, D, E, F, G. G is a fifth above C.
Each time you go to the next key a fifth higher, you add 1 sharp.
C major contains 0 sharps or flats. A fifth above C is G. The next key on the circle is G major and it contains 1 sharp F#. G major is spelled: G, A, B, C, D, E, and F#.
Moving a fifth up from G brings you to the key of D. D major contains 2 sharps F# and C#. D major is spelled: D, E, F#, G, A, B, C#.
The pattern of adding one sharp each time you move up a fifth continues all the way around the circle until there are no more notes to sharp. (The key of C# major has all seven notes sharped.)
At the bottom of the circle of fifths diagram you will notice 3 keys each spelled two different ways. These keys use the same pitches, but one spelling uses sharps while the other spelling uses flats. Sometimes choosing a spelling in flats is preferable to a sharp spelling. At a later time we will look at why one might be preferred to the other. You should memorize all 15 major key spellings.
Now you know how to determine how many sharps or flats are in each key, but how do you know which ones are sharp or flat? That's where you need to learn one more piece of information the order of sharps and flats.