How to Read Musical Key Signatures

Updated on May 30, 2013
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JohnMello is a writer, composer, musician and the author of books for children and adults.

Find out how to take the confusion out of some of these musical symbols
Find out how to take the confusion out of some of these musical symbols | Source

Tones & Semitones

On the piano or keyboard a semitone is the distance between any note and the very next one, regardless of their color. A tone is made up of two semitones. The distance from the note E to the note F is a semitone, because there are no other notes in between. The distance from A to B is a tone, because there's a black note in between.

If you've never tried it before, reading music can be a real challenge. One of the most difficult things to get under your belt when you start is the concept of keys and key signatures. Faced with 7 sharps or flats it can be tricky to try to work out exactly what you're supposed to do.

Sharps and flats get their names from the way they're used in the music. Sharps raise a note by a semitone, and flats lower a note by a semitone. In practice that means the following:

  • A sharp in front of the note F turns it into F sharp
  • A flat in front of the note B turns it into a B flat

Recognizing Key Signatures

When the sharps or flats appear at the beginning of a piece of music, we call that its key signature. When they appear in the music, we call them accidentals.

If there are no sharps or flats, you're in the key of C major. The key of C major goes from one C up to the other, using no black notes.

If there's a G sharp written into the music, that's an accidental. It's there to tell you that the key signature (no sharps, no lfats) belongs to the relative minor of C major, which is A minor. G sharp is A minor's leading tone.

The key signature for C major shows no sharps or flats
The key signature for C major shows no sharps or flats | Source

Key Signatures and the Circle of Fifths

Keys and key signatures work on what's known as the Circle of Fifths. If you go up 5 notes from C, you come to G. G major is the first sharp key, with one sharp. The sharp in G major's key signature is F sharp, the leading tone. Keys with more than one sharp also include the leading tone, as well as other sharp notes as required.

For flats, work in the opposite direction. If you go 5 notes down from C, you come to F. F major is the first flat key, with one flat.

That's easy enough when the key in question has only one sharp or flat, but what about when there are lots of them?

To find the key of a piece with five sharps, for example, simply work it out using the Circle of Fifths. Here's how to do it:

  • 5 up from C is G (one sharp, which must be F sharp, G's leading tone).
  • 5 up from G is D, which will have F sharp but also C sharp, its leading tone.
  • 5 up from D is A, with three sharps, F, C, and G.
  • 5 up from A is E, with four sharps: F, C, G, and D.
  • 5 up from E is B, with five sharps: F, C, G, D, and A.

For Flats Work Down the Keyboard

To find the key when there are loads of flats, do the same working in the opposite direction. A key signature with 5 flats, for example, means you have to work down as follows:

  • 5 notes below C is F (the first flat key with 1 flat)
  • 5 notes below F is B (the second flat key with 2 flats), which is obviously B flat
  • 5 notes below B flat is E flat (3 flats)
  • 5 notes below E flat is A flat (4 flats)
  • 5 notes below A flat is D flat (5 flats)

There can be seven sharps in total (which makes the key of C sharp major). They always follow the same order, which is: F, C, G, D, A, E, B -- each one 5 notes higher than the one before. The order in which the flats appear in a key signature is the same thing BACKWARDS - B, E, A, D, G, C, F.

C sharp major has seven sharps in total
C sharp major has seven sharps in total | Source

Keys & Key Signatures

Sharp Keys
Key Signature
Flat Keys
Key Signature
C major
No sharps
C major
No flats
G major
1 sharp
F major
1 flat
D major
2 sharps
B flat major
2 flats
A major
3 sharps
E flat major
3 flats
E major
4 sharps
A flat major
4 flats
B major
5 sharps
D flat major
5 flats
F sharp major
6 sharps
G flat major
6 flats
C sharp major
7 sharps
C flat major
7 flats

Working Out Key Signatures

Here's an example of how to find out what key a piece is in just by looking at the key signature.

We know the order in which the flats appear is B, E, A, D, G, C and F. A key with four flats in the key signature, then, would have to include B, E, A, and D flats. To find out which key that puts the music in, just back up one, or go back to the second-last flat listed in the series. So the key with four flats would be - A flat major.

To work out a minor key, count the sharps or flats as above, and then check for accidentals (an extra sharp or natural written in the music). So, for instance, a piece with 3 sharps could be in the key of A major or its relative minor, F sharp minor. If it's the latter, there'll be E sharps written in the music as well.

Likewise, a piece with three flats will either be in the key of E flat major or that of C minor. If there's a B natural written in, it's most likely going to be C minor, with B natural being the raised leading tone.

The Circle of Fifths showing sharp keys on the right, flat keys on the left, and minor keys on the inner ring
The Circle of Fifths showing sharp keys on the right, flat keys on the left, and minor keys on the inner ring | Source

Until you get used to reading key signatures, copy or print out the Circle of Fifths to make it a bit easier. As with everything else in life, practice makes perfect, and to give you a little more practice - try the quiz below!

Key Signatures Quiz

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Questions & Answers


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      • JohnMello profile image

        JohnMello 2 years ago from England

        Hi Bob

        Thanks for the comments. I remember when I started learning that I always struggled with the "5 up from C is G" concept - but you always have to count the C and the G to make up the 5. Maybe that's because C to G is a 5th.

        Anyway, as long as what you're doing sounds good, then you're making music. It's not all about technical info.

        Thanks for pinning and following too!

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        Robert E Smith 2 years ago from Rochester, New York

        Well, I was taking a break from updating some old hubs and I see this article about reading the circle of fifths, without a doubt the hardest thing I have ever tried to learn. But an old dog learns tricks in a slow but positive way when he really desires to... The first thing I see is the statement I see is: "5 up from C is G" and I keep counting four not five. So I take from this that I had come right out of the box counting wrongly. I will really read this over and over until I can "see" it. I pinned your article on my "How-To's" board and will follow you on Hubpages.

        I have told many people my sad no music in my childhood story. But the short of it is that I am learning of necessity on my own. I can play as many 0f sharps or flats as there are only because I have memorized where they are on the lines and not because I'm understanding the keys. I guess the song comes out the same but I'm really not comprehending the music "science" or however I should state it. All I know is that the noise I make with my double alto and triple bass ocarinas sound good to me. But, like Data on Star Trek, "I aspire to be more." Thank you for the article and in your own way the encouragement. Bob.

      • JohnMello profile image

        JohnMello 4 years ago from England

        Thanks Eric. Glad it was of use and happy it brought back good memories...

      • Eric Prado profile image

        Eric Prado 4 years ago from Webster, Texas

        This has been helpful and really took me back to my days in band. =) Voted up. Great hub.