Jan 07

Music Theory Basics Part 3: Key Signatures

In the first two parts of Music Theory Basics, we covered a lot of topics.  Today we will only be focusing on one topic: key signatures.  There are, however, several layers to this concept.  I will try an lay it out in a way that makes it a tasty parfait and not an onion.

Let’s start with a little background.

Western music (music originating from western Europe) evolved from ancient Greece.  Back then, music was learned, performed, and passed down by ear.  The Greeks used a system of modes.  Each mode had different “rules” of what the musician would play.  These rules determined, among other things, whether or not a note was sharp or flat.  From the modes developed, what we call, scales.  When music began to be written down, scribes noticed these “rules” for each scale and began to use key signatures to indicate the notes that would be consistently sharp or flat.

With and Without key signature

Key Signature: Generally written immediately after the clef, it is a series of sharp or flat symbols (AKA: accidentals) placed on the staff denoting which notes are consistently played sharp or flat.

key signature

  • Accidentals: Includes, sharp, flat, and natural signs.  Accidentals are used to alter the pitch of a note higher or lower.
  • Sharp: Means higher in pitch.  Notes with the sharp symbol in front of them, or that are indicated as sharp within a key signature, are to be played a half step higher that their natural counterpart.  For instance, an A-sharp is a 1/2 step higher that an a-natural.


  • Flat: Means lower in pitch.  Notes with the flat symbol in front of them, or that are indicated as flat within a key signature, are to be played a half step lower that their natural counterpart.  For instance, an A-flat is a 1/2 step lower that an A-natural.



  • Natural: the natural sign cancels any previous accidentals and returns the notes to its unaltered or natural state.


Now, I wish that I could say that once the key signature is set, you don’t have to worrying about it changing.  Key signatures can change often in a piece of music.  Plus, composers often use accidentals in places that they want harmony get interesting.  You will see the symbol directly in front of the note and that accidental applies for the entire measure.


So, now that you understand all the symbols, how do you know what key you are in.  You could just learn by rote.  I like to use the following chart, though.  It is known as the Circle of Fifths.  I’m going to try by best to explain this briefly, but I could get a little long.  If you want to skip the explanation and just take the chart at face value, great.  There’s no quiz on it.  Just trust me it works.

circle of fifths

Want more information? It is called the Circle of Fifths because the key signatures are listed a fifth apart (meaning they are five notes apart including the starting note).  At the top of the circle, we have the key of C, the key of C has no sharp or flats.  It’s all natural.  If you were go up the scale by a fifth from C (C, D, E, F, G-that’s five!) you land on G.  The key of G has 1 sharp.  A fifth above G is D.  The key of D has two sharps and so on and so forth.  The more you advance by fifths, the more sharps you get.  You can see this pattern by going clockwise around the circle of fifths.  To determine a key signature that is full of flats, you must go counter-clockwise and you descend by fifths.  A fifth below C (C, B, A, G, F) is F.  The key of F has one flat.  Likewise, a fifth below F is B-flat.  The key of B-flat has two flats, and so on.

One thing that is tricky, is when you reach the bottom of the circle of fifths.  The flat key signatures and the sharp key signatures run together.  What’s happening there, we call enharmonic tones.

  • Enharmonic tones: They are two notes that are equivalent to each other.  For instance, F-sharp is an enharmonic tone to G-flat. Basically, an individual tone can have multiple names.  Still a little confusing?  Think about playing a piano.  If you start on G-natural, the black key below it is G-flat, but that is also the black key above F which we know as F-sharp.


What that translates to in the circle of fifths is that the key of C-flat major contains the enharmonic tones of a B major scale.

If the Circle of Fifths is not your cup of tea, check out Ricci Adams’ mathematic method.

We’ll stop there for today.  Our basics are quickly are becoming more advanced.  The last installment of Music Theory Basics, will cover intervals, scales, and the function of each note within the scale.



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  1. Jerry Rice

    Very good timing with your key signature information. I have been studying key signatures. I like the circle of fifths, but would like to be able to look at a piece of sheet music and know what it’s to be played in. I looked at Ricci Adams math method that you mentioned, but not able to see through it. I appreciate your instructional additions. If you should happen to have some other way of looking at key signatures, please let me know. Thanks, Jerry email: jerry-pc@comcast.net

    1. Rachel Davis

      I am glad my timing works for you. With the circle of fifths, it does take some practice to get the pattern down. In college, I used to have a copy of the chart taped to the back of my music theory book until I knew it better. It helped me to know that the order of keys also follows the order of sharps/flats. The “quick and dirty” way to figure out a key signature is to look at the last note in the melody of a piece of music. 80% of the time, that note is also the name of the key signature.

  2. Jerry Rice

    Rachel, In this one edition on key signatures, you have captured more points to help understand key signatures than I have collected from half a dozen web sites that would fill half a notebook. Many Thanks, Regards, Jerry

    Other ideas that would help would be pieces to practice on the E,A,D, and G string to help with finger positioning. Doing each string individualy several times before moving on to the next string.

  3. Learn Violin

    I have only recently learned to appreciate the beautiful sounds that the violin makes. Have enjoyed reading your blog and bookmarked it.

  4. melanrainbo

    I totally agree that every new habit begins with mental shifts.

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