What is a Key Signature?

Have you ever noticed that at the beginning of some pieces of music, there is often a group of sharps or flats before the music even starts like this?

Key Signature
Key Signature

This is an example of a key signature. A key signature is a symbol at the beginning of a song that tells us which piano notes will be sharp or flat for the rest of the song, but even more than that, it tells us what scale the song got its notes from. With the above example, we can see that every B, E, and A in the song will be flat. The scale that has 3 flats (B♭, E♭, and A♭) is E♭ (E flat) major, so the key signature is actually telling us that this song was created using the notes in the E♭ (E flat) major scale. Cool, right? I knew we learned all those scales for a good reason!

How to Read Key Signatures: The Simplest Trick in the World

Why is it important to know what the Key Signature is for a song?

Not only does the key signature help you understand which sharps and flats to use in a song, it can also help you to understand what chords you might encounter while playing the song. Since each “key” or “scale” has certain sharps or flats associated with it, there are certain chords that are also associated with each scale. For example, C major scale doesn’t have any sharps or flats in it. So when you are playing chords for a song in C major, the chords won’t have any sharps or flats either.

C Major Chords
C Major Chords

These are the chords that are most commonly seen when playing a song in the key of C major. As you can see, there are no sharps or flats in any of these chords. They are labeled by a number based on what note of the C major scale they start on. When playing pop songs, we often will see these chords labeled like this: C, Dm, Em, F, G, Am, Bdim. In other words, if you are playing a song in C major (which has no sharps and flats) and you see a chord labeled “Dm”, you can easily figure out how to play it on the piano by building a chord with D on the bottom and simply playing only the white notes on the piano. This is one of the reasons why knowing your key signatures is so important.

Where does the Key Signature come from?

A major scale sounds like it does (do, re, mi, fa, sol, la, ti, do) because it is built of a pattern of tones (T) and semitones (S). This pattern operates kind of like a recipe. If you follow the recipe of tones and semitones, any scale you build will sound like a major scale. A semitone is the smallest space between two notes. On the guitar, each fret is one semitone. On the piano, a semitone is a space from one note to its next closest neighbour (either a white note or a black note). A tone is simply two semitones put together. Here is the C major scale as it looks on the piano.

C Major Scale Intervals
C Major Scale Intervals

Notice the pattern of tones and semitones: T, T, S, T, T, T, S. Let’s apply this recipe to build another scale by starting on another note. Why don’t we use the E♭ (E flat)  major example from the key signature example we used at the beginning.

E Flat Major Scale
E Flat Major Scale

If we start on E♭ (E flat) and move up one tone, the next note in the scale will be F. Move another tone, and we are on G. Now it is time for a semitone. This puts us on a black note which we can either call G# or A♭ (A flat). Since we already have a G in our scale, we need to use A♭ (A flat). We can only use each letter name once in a scale. After A♭ (A flat) we move a tone that brings us to B♭ (instead of A#). Another tone after B♭ (B flat) brings us to C and then we move another tone to D. Finally, the last semitone in the pattern brings us back to E♭ (E flat). So, the notes of the E♭ (E flat) major scale are: E♭, F, G, A♭, B♭, C, D, E♭. If we look back to the key signature at the beginning, we can see that it has 3 flats notated: E♭, A♭ and B♭, just like our scale! Key signatures are like a shorthand symbol to represent these different scale patterns.

Key Signature Rules

There are a few key signature rules to help us:

  1. There is only one major scale for every key signature.
  2. Major scales use either flats or sharps but never mix the two.
  3. The highest number of sharps and flats you can have in a scale is 7.
  4. The order of sharps and flats follows a specific order and that order never changes.
  5. When writing key signatures, the sharps and flats are always written on specific lines/spaces. For example, the F# in the treble clef will ALWAYS be on F♯5 (F sharp 5) (the highest F) and not F♯4 (F sharp 4) (the lowest space).

The Order of Sharps

Order of Sharps - Music Theory Crash Course

When you are working with key signatures involving the order of sharps, the sharps always occur in a specific order. A good way to remember the order is the mnemonic Father Charles Goes Down And Ends Battle. When you have a scale with one sharp in it, that sharp is always “Father” or F♯ (F sharp). A scale with 2 sharps would have “Father Charles” or F♯ (F sharp) and C♯ (C sharp). The key signature with 3 sharps would have “Father Charles Goes” or F♯ (F sharp), C♯ (C sharp) and G♯ (G sharp), and so on. Here is what the sharp key signatures look like. Notice which lines/spaces have the sharps:

The Order of Sharps
The Order of Sharps

The Order of Flats

Order of Flats - Music Theory Crash Course

When you are working with key signatures involving the order of flats, the flats also occur in a specific order. To remember this order, take your “Father Charles” mnemonic and say it backwards: Battle Ends And Down Goes Charles’ Father. Just like with the sharp scales, if you have a key signature with one flat in it, it would be “Battle” or B♭ (B flat). Two flats would be “Battle Ends” or B♭ and E♭ (E flat) and so on. Also, like the sharps, each flat is on a specific line/space. Notice that E flat in the treble clef is ALWAYS on E♭5 (E flat 5) and not E♭4 (E flat 4). Here is what the flat key signatures look like:

The Order of Flats
The Order of Flats

How to use The Circle of Fifths

The Circle of Fifths - How to Actually Use It

Now that you understand how the sharps and flats work, it’s time to learn how to figure out which scales have which key signatures. To do this, many people use the “Circle of Fifths”. The Circle of Fifths is the way these key signatures are organized. It is based around the principle that each key signature is the interval of a perfect fifth away from the next. For example, if C major scale has no sharps and flats, then if you move up by a perfect 5th, you should find the scale that has one sharp. That would be G major. If you go up by another perfect 5th, you will find the scale that has two sharps. That would be D major. For the flat scales, you start with C major and go down a perfect 5th to find the scale with one flat. That would be F major. Here is a diagram of what the Circle of 5ths looks like:

Circle of Fifths Key Signatures
Circle of Fifths Key Signatures

How to memorize The Circle of Fifths

Confusing, right? Many musicians have just learned to memorize the key signatures because the Circle of 5ths just seems too complicated. Here is an easier way to figure out the major key signatures. To do this, all you need to remember is the “Father Charles…” mnemonic and that C major scale has no sharps or flats.

Key Signatures Memorization

Start counting your sharps on the word “Charles” to represent 0 sharps for C major. Now add one sharp as you continue through the words until you come back to Charles, which represents C♯ (C sharp) major and its 7 sharps. Another handy trick is the saying “C is all or nothing”. C♯ (C sharp) major has all the sharps and C major has nothing.

Let’s use the same trick for the flats using the “Battle Ends…” mnemonic.

Circle of Fifths Mnemonic

Just like the sharp key signatures, you start counting from “Charles’” or C major, since we know that C has no flats. In this case, it just takes a little farther along the mnemonic to reach “Charles’”. Notice that all the flat scales actually have a “b” beside their names except for F major. In this way, F major is “funny”. It is the only flat scale without a “b” in its name. Also, notice that in the flat key signatures, C is still “all or nothing”.

What about Minor Key Signatures?

Not all songs are written using major scales/key signatures. Have you ever heard a song or chord that sounds “sad”? That song is probably written using a minor scale/key signature. Don’t worry! You don’t have to learn a whole new set of key signatures for minor scales. Minor scales actually just hijack the key signature of a major scale. They are like musical freeloaders.


  1. Every major key signature has a minor scale that shares its key signature.
  2. We call these major/minor pairs “relative” majors/minors because they share the same notes just like relatives share the same genes.
  3. To find a minor scale’s key signature, you simply go up 3 semitones to find its major relative.

Use this house diagram to help you figure it out:

Minor Key Signature
Minor Key Signature


The Sad Story of a Minor Key Signature

Once upon a time, in the house of 0 sharps/flats, there was a happy scale/key signature that lived in the top of a house where life was good. It is sunny up there and things are happy. But if you went down 3 semintone stairs, you would find yourself in the basement of the house. It is darker down there and a little depressing. In this basement, lived a sad relative called the relative minor. They didn’t have their own key signature, but had to borrow the one from their happy upstairs relative.

Since both key signatures live in the same house, both scales have 0 sharps/flats.

Using this house, we know that C major is the scale that lives at the top of this house because it has 0 sharps/flats. If you go down 3 semitones from C, you will be on A. So, the minor scale that lives in this house is A minor. A minor scale has 0 sharps/flats. If you play from A-A on the piano using only the white keys, you will notice that the scale sounds a little sad.

Now you’re ready to go! Using these helpful hints, you should be able to figure out any key signature that comes your way.  Speed up the music theory learning process with a professional piano teacher at Merriam Music, Canada’s #1 Piano School.

Key Signature Chart

We have put together two handy key signature charts for both Sharp Major Scales and Flat Major Scales.  Use these charts as a guide to helping you learn to identify major Scale Key Signatures as you progress in your journey learning music theory.

Sharp Major Scale Key Signatures Chart

Key SignatureNumber of SharpsSharp NotesMinor keyEnharmonic equivalent
C major0NoneA minorNone
G major1F♯E minorNone
D major2F♯ C♯B minorNone
A major3F♯ C♯ G♯F♯ minorNone
E major4F♯ C♯ G♯ D♯C♯ minorNone
B major5F♯ C♯ G♯ D♯ A♯G♯ minorC♭ major/A♭ minor
F♯ major6F♯ C♯ G♯ D♯ A♯ E♯D♯ minorG♭ major/E♭ minor
C♯ major7F♯ C♯ G♯ D♯ A♯ E♯ D♯A♯ minorD♭ major/B♭ minor

Flat Major Scale Key Signatures Chart

Key SignatureNumber of FlatsFlatsMinor Key
Enharmonic Equivalent
C major0NoneA minorNone
F major1B♭D minorNone
B♭ major2B♭ E♭G minorNone
E♭ major3B♭ E♭ A♭C minorNone
A♭ major4B♭ E♭ A♭ D♭F minorNone
D♭ major5B♭ E♭ A♭ D♭ G♭B♭ minorC♯ major/A♯ minor
G♭ major6B♭ E♭ A♭ D♭ G♭ C♭E♭ minorF♯ major/D♯ minor
C♭ major7B♭ E♭ A♭ D♭ G♭ C♭ F♭A♭ minorB major/G♯ minor

Quiz Materials (PDF Download)

When you feel comfortable that you are able to start identifying most of the key signatures you can download the worksheet PDF document “Quiz PDF – Questions”, print the document, and fill in your answer under each image.  When you finish that you can download the PDF “Quiz PDF – Answers” to review you answers and see how many you got correct.

Download: Quiz PDF – Questions

Download: Quiz PDF – Answers