Key Signature Calculator

This key signature calculator consists of two parts: a music key finder, which determines what key you're in based on the number of sharps/flats; and the key signature finder, which finds the flats or sharps you need in a particular key.

In the text below, we'll cover some theories on the subject, including:

• What is a key signature in music? (key signature definition);

• How to identify key signatures;

• How to use the music key finder app; and

• A list of key signatures.

A key in music tells us which set of notes we use in a song. We say a piece is in the key of C major when we use only (or almost only) notes in the C major scale. Learn more about music scales by visiting our music scale calculator.

A key signature is a section of sheet music that tells us what key we're in and what notes on the sheet have sharps or flats. The section is located at the beginning of each line, between the clef and time signature:

There are 15 key signatures - 7 with flats, 7 with sharps, and one with no sharps or flats. Take a look at the lists of key signatures:

Each key signature corresponds to one major key and its relative minor. A relative minor key is the key which uses the same set of notes as a major key but has a different tonic. For example, C major consists of the same sounds as A minor:

C major: C, D, E, F, G, A, B,

A minor: A, B, C, D, E, F, G.

As you can see, both keys use no sharps or flats, so if you can't see any symbols next to a clef, it means you're either in C major or A minor.

There are certain tricks you can use to identify key signatures. To find what key you're in, you can:

• Find the note with the last sharp and go a tone up.

  For example, if you have one sharp on the fifth line of the staff, it means you'll have to raise F. If we go a tone up from F we get a G. The key with one sharp is G major.

• If you're dealing with flats, read the penultimate flat — this will be the key.

  For example, you have 3 flats, and the penultimate is B♭ — which means you're in B♭ major.

• To find the relative minor key, count down 3 notes from the root of the major key.

  For example, the D major scale consists of D, E, F#, G, A, B, C#, D. Let's find the third note from the end: D, C#, B. B minor is the relative minor of D major.

To find whether you're in a minor or major key, you can check the first and last bass note or chord. The note will determine the key in the majority of music.

What if you want to know how many sharps or flats a particular key has (for example, when you write sheet music yourself)? A useful key signature chart called the circle of fifths can help you in such situations:

The major keys are placed in the outer circle and their relative minors are in the inner circle. Between them, you'll see the corresponding flats and sharps. The adjacent notes are a perfect fifth apart (hence the chart's name). Going from C, we add sharps going clockwise and flats going counterclockwise.

To remember the order of sharps and flats, you can use this popular mnemonic:

• Father Charles Goes Down And Ends Battle (for sharps)

  F, C, G, D, A, E, B

• Battle Ends And Down Goes Charles Father (for flats)

  B, E, A, D, G, C, F

To recreate the key signature chart from memory:

1. Recall the sentence: "Father Charles Goes Down And Ends Battle".

2. Draw a circle with 12 evenly spaced places for notes.

3. Remember C has no sharps or flats; write it at the top of the circle.

4. Starting from the place to the left from C and going clockwise, enter the first letters of the mnemonic: F, (C), G, D, A, E, B.

5. After "B," continue filling the circle with first letters from a shortened part of the mnemonic: "Goes Down And Ends Battle". Add a flat to each letter. You'll have (G♭, D♭, A♭, E♭, B♭)

6. You can write down the number and names of sharps on the right part of the circle and flats on the left using the same mnemonic.

Now that we know how to remember key signatures, let's go through some exercises.

Let's go through some examples to better learn how to find key signatures.

Example 1: find the 3 sharps key.

• To recall the first three sharps, we use the mnemonic "Father Charles Goes (...)" (we don't need to recall the rest of the sentence) and get the first letters: F, C, G.
• We take the last note - G - and go a tone up.
• We get A - The 3 sharps key is an A major key signature.

Example 2: find the 6 flats key.

• We recall the order of flats: "Battle Ends And Down Goes Charles' Father".
• We enumerate the first letters of the first 6 words: B, E, A, D, G, C.
• We read the penultimate note - G - and add a flat, which gives us G♭. The 6 flats key is G♭ major.

Example 3: find what D major's key signature is.

• We again use the mnemonic and enumerate the keys until we get to D. We recall C has no sharps or flats:

  (Father)

  Charles - C - 0 sharps

  Goes - G - 1 sharp

  Down - D - 2 sharps

• We now know D major has 2 sharps.

• To get the names of the first 2 sharps, we need the first two words of the mnemonic: "Father Charles (...)" - F and C. This means D major has 2 sharps - F# and C#, so the whole scale would be: D, E, F#, G, A, B, C#.

Example 4: identify B minor's key signature

• We can list the order of major keys in the circle of fifths and check which one is relative to B minor. To find the relative minor, we list 3 notes down the major scale. There we go:

  Charles - C

  3 notes down the scale are C, B, and A. Therefore, the relative minor of C major is A minor.

  Goes - G

  3 notes: G, F#, E. Relative minor: E.

  Down - D

  3 notes: D, C#, B. Relative minor: B.

  We've found it. B minor is a relative key of D major. Its key signature is the same: 2 sharps - F# and C# (see the previous example).

It takes a while to check key signatures this way so let's see how the key signature calculator can help you when you need to get the answer on the go.

This key signature calculator has two functionalities:

• A key finder (you know the number of sharps/flats and want to check the key);

• A key signature finder (you want to check what sharps/flats a key has).

Choose one of the above options in the first field of the key signature calculator.

If you chose the first option, enter the number (from 0 to 7) and type of symbols in the key signature. The key finder will tell you what major and minor key corresponds to the given signature.

If you chose the second option from the key signature calculator, choose the key's quality (major/minor) first. It will change the list of notes below, from which you need to select the root note. Once you do, the key signature finder will tell you how many and which flats or sharps the specified key has.

Note: we didn't include theoretical keys (key signatures with double flats and sharps) in the key finder as they're rarely used.