Understanding Key Signatures

One of the hardest concepts for many musicians is memorizing and understanding how key signatures work.  Many systems have been developed to help growing players in this pursuit, including the circle of fifths.  Many of our students struggle with these concepts and may not even understand their value or why key signatures are such a fundamental part of studying music.  In this lesson, we will discuss what key signatures are, how they work, and why we need to know them as musicians.

Put as simply as possible key signatures work to tell us what notes are in a specific song, and what those notes are called.  One of the most challenging parts of studying music is that some notes have different names in different situations.  How are we to know which name is right and why?  This is one of the most important functions of a key signature.  As we get more advanced in our understanding we can also use key signatures to give us a guideline for what chords to use in a song.  We can also use our knowledge of key signatures to help us learn someone's song faster and more accurately.  Whenever we study a song the first question we seek to answer is what key is this song in.

Now that we understand what key signatures are, we can start to think about how many are there, whether there are different kinds, what are they called, and how are they identified.  There are a total of 30 key signatures in music.  This sounds like a lot, but when we divide them into two categories we can simplify our job of memorization.  There are two kinds of key signatures, Major and Minor, which may be terms you are already familiar with.  There are a total of 15 major and 15 minor keys, when added up that is how we reach a total of 30 different keys.

Now that we know there are 30 total keys and two kinds of keys how do we know whether an example is a major or minor key?  This is a very good question with less than a simple answer.  When determining a key we need to know how many accidentals are being used.  Accidentals are either sharps, which look like a hashtag, or flats that look like a lowercase b.  (See example 1) Key signatures will either use sharps or flats and can have anywhere from zero to seven of them at a time.  If you have a key signature with zero accidentals then we can narrow down the potential keys to two options, either C major or A minor.  The number of accidentals is the most important factor to narrow our options down to two potential keys.  Then to know whether it is major or minor requires us to find the note that “sounds like home”.

Example 1

When counting accidentals we have a set order in which the keys will appear.  (See example 2)

So for sharps, it will be C G D A E B F sharp C sharp major, those correspond to A E B F sharp C sharp G sharp D sharp A sharp minor. On the flat side, the order is C F B flat E flat A flat D flat G flat C flat major, those correspond to A D G C F B flat E flat A flat minor. Each time we move from one key to the next we are always adding an accidental, and once we add an accidental we keep it until there are a total of seven accidentals in a key.

Example 2

One tip to make this all much easier is, to consider that seven is the most accidentals a key can ever have.  When we look at G major, which has one sharp, we subtract one from seven to get six, and we can determine that Gb major has a total of six flats.  This pattern is true no matter what letter we are looking at, A major has three sharps, meaning A flat major will have a total of four flats.  This knowledge can save us a lot of time and frustration.  The more we can correctly identify the number of accidentals the easier it will be to determine what major or minor key you are working with.  Try to practice every day identifying a key based on the number of accidentals and over time you can begin to memorize them.  Remember that memorization is less important than being able to find the right answer using the pattern.