A key signature is a collection of accidentals (sharp and flat symbols) that let you know what key a piece of music is in. These accidentals apply throughout the entirety of the piece unless otherwise noted either by a new key signature (called a key change) or with new accidentals attached to a note (one off flat, sharp, or natural signs.)
When you see it, you lower the pitch by a half step.
This symbol means you raise the pitch by a half step.
It means that you play the pitch without modification.
A key signature will only contain one kind of accidentals, either sharps or flats, but never both. You will find it right next to the clef symbol at the beginning of the staff. Accidentals in the key signature always live on the staff line of the note they affect. Look below and you will see a sharp symbol on the F staff line and the C staff line. That means this key signature has two sharps: F-sharp and C-sharp.
Accidentals in the key signature are always written in the same order. Flats are written in this order: B, E, A, D, G, C, F Sharps are written in this order: F, C, G, D, A, E, B
Below is a table that will let you know how many accidentals (sharps or flats) each key signature has. We show name in both the Major key and minor key. You will notice, when you write Major keys, you write the letter as a capital letter. Minor keys are always written in lower case.
|Number of Accidentals||Major Key||minor key|
|No sharps or flats||C Major||a minor|
|One flat||F Major||d minor|
|Two flats||B-Flat Major||g minor|
|Three flats||E-Flat Major||c minor|
|Four flats||A-Flat Major||f minor|
|Five flats||D-flat Major||b-flat minor|
|Six flats||G-Flat Major||e-flat minor|
|One sharp||G Major||e minor|
|Two sharps||D Major||b minor|
|Three sharps||A Major||f-sharp minor|
|Four sharps||E Major||c-sharp minor|
|Five sharps||B Major||g-sharp minor|
|Six sharps||F-Sharp Major||d-sharp minor|
Here is what key signatures with sharps look like across different clefs.
And here is what key signatures with flats look like across different clefs.
If you look at the chart above, you can see that every key signature can be called by two different names: A Major and a minor key. What makes a scale a Major scale is th intervals between notes. The first note of the scale is always the same as the note they key signature is named after. As an example, the F major scale will always begin on the note F.
Let us look at a sample scale. If we look at the key signature, we see that there are no sharps and no flats. Looking at our table we know that this must be the C-Major scale. It begins on the note C.
The distance between notes are called intervals. Major scales are sound the way they do because of the pattern of intervals. Major scales are made up of whole steps (or Major seconds) and half steps (minor seconds). A Major scale has all whole steps and two half steps; one between the 3rd and 4th note and one between the 7th and 8th note (when discussing scales, it is more common to say "degree" instead of "note"). I have written the interval between each step of the major scale. They will always follow this pattern no matter what key they are in. There are twelve Major scales, one for each key. Some of you might go back to the chart and see that there are 13 different keys, so why are there only 12 Major scales? Remember that notes can sound the same but be written in different ways; a B-flat is the same as an A-sharp. The scale with six flats (G-flat Major) and the scale with six sharps (F-sharp Major) are the same scale!
Like Major scales, minor scales sound the way they do because of the intervals between scale degree. However, unlike Major scales, there are three different minor scales for each key signature. Each with slightly different intervals. Let us continue with our examples of having no sharp or flats in the key. This time, instead of C-Major, our key signature is a-minor.
Just like with Major scales, we see that the minor scale starts on the note named in the key signature. A-minor begins on the note A. If you were to play through this scale, it would sound distinctly different from the Major scale, and that is because the intervals between each note are different. In the natural minor scale, the half steps occur between the second and third degree and the fifth and sixth degree.
The harmonic minor scale begins the same, but you will see that there is an accidental in this scale; there is a sharp sign on the seventh degree. Raising the seventh degree by a half step changes the intervals between it and its neighbors. There are now three half steps. One between the second and third degree, the fifth and sixth degree, and the seventh and eighth degree.
The melodic minor scale the 6th and 7th scale degree are both raised a half step. Like we saw with the harmonic minor, this changes the intervals. There are half steps between the second and third degree, and the seventh and eighth scale degree. The melodic minor scale has something else that makes it different; these changes only apply on the way up the scale. When you descend, you play the natural minor scale.
You might recall that sharp accidentals raise a note by a half step and flat accidentals lower the pitch by a half step. This means that some notes will sounds the same but can be written in different ways. For example: B-flat could also be written as A-sharp. They will sound the same pitch. This can become complicated when notes are already a half step apart (E&F or B&C). Just imagine a piano keyboard. Keys that neighbor each other are a half step apart. The B key and the C key touch. They B-flat key (black) and the C key (white) have a note in between. This means they are a whole step apart.So, an B-sharp is not an C-flat, it is just an C.
If you would like to practice a piece of music in a given key, then we recommend checking out our piano keyboard tool. Just press the piano key that corresponds with your key signature.