How to Determine the Key of Sheet Music

By Carl Hose ; Updated September 15, 2017

A key signature is the way that musicians know what scales and notes to play in a piece of music. There are twelve tones in the Western musical system. These tones are arranged in scales, according to steps that dictate natural, sharp and flat notes contained within the scale. Learning to read key signatures isn't difficult. The key signature is located at the beginning of a piece of sheet music, indicated by the absence or presence of sharp and flat signs. Memorizing the arrangement of these sharp and flat signs is the key to determining a the key signature.

Examine a piece of sheet music. Start at the beginning of the piece, in the first measure. If there are no sharp (#) or flat (b) signs, the music is in the key of C. If there is one sharp, the key is F. If there is one flat, the key is B flat. You should memorize these three keys. If you know them, you can easily figure out the key of any piece of music by glancing at the fjrst measure.

Memorize "Fat Cats Go Down Alleys Eating Bologna". The first letter of each word will help you to recognize the order that sharps are added to a key signature. If there is only one sharp in the key signature, it will be an F sharp; if there are 2 sharps, they will be F and C; three sharps will be F, C and G.

To figure out the name of the key signature, add a half step to the last note in the series. For example, if you have two sharps, they will be F and C sharp. A half step up from C sharp (the last sharp in the series) is D. You can conclude that D is the key signature with two sharps, F and C.

Memorize the phrase, "BEAD Go Catch Fish" to help you figure out the order that the flat notes are added to the key signature. If there is one flat note in a key signature, it will be B flat. If you have two flats, they will be B flat and E flat. To determine the name of the key, look at the second to last flat--that will be the name of the key. For example, three flats in a key signature will be B, E and A flat. In this case, the key signature will be E flat. Since B flat is the first flat note in the series, you can't use this method to figure out the name of the key. Just remember that one flat (B flat) is the key of F.

Purchase a circle of fifths from a music store. You should keep it handy as you study music keys. You can also find one online at no charge. The circle of fifths shows the relationship of the twelve musical tones, their key signatures, and the applicable major and minor scales. The circle of fifths, starting at C and counting five notes (a perfect fifth) takes you through the major keys with sharp notes; moving counterclockwise and counting four notes (a fourth) takes you through the major keys with flat notes. The circle of fifths is an effective way to visualize and learn the major and minor keys.


When moving up or down by a half step, there are no sharps or flats between B and C or between E and F. The twelve notes of the musical scale are C-C#-D-D#-E-F-F#-G-G#-A-A#-B.

The relative minor of any major key is the note a third below the major key; counting back three notes from C brings you to a. A minor is the relative minor of C and shares the same key signature.

About the Author

Carl Hose is the author of the anthology "Dead Horizon" and the the zombie novella "Dead Rising." His work has appeared in "Cold Storage," "Butcher Knives and Body Counts," "Writer's Journal," and "Lighthouse Digest.". He is editor of the "Dark Light" anthology to benefit Ronald McDonald House Charities.