Why do sharps and flats stop at seven?

Because a key needing eight would have to alter a note that is already altered, which means a double sharp or double flat in the signature. Rather than notate that, the far keys are written in their enharmonic equivalents, so the practical range is seven of either.

What order do the accidentals come in?

Sharps appear as F sharp, C sharp, G sharp, D sharp, A sharp, E sharp, B sharp, and flats as B flat, E flat, A flat, D flat, G flat, C flat, F flat. In both cases each new accidental is a fifth from the one before, which is why the orders are fixed and never vary between pieces.

Why can a signature not have both sharps and flats?

Because a key is defined by which notes are altered from the natural scale, and a mixture would describe a different set of notes rather than a transposition of it. Selecting both is therefore treated as an impossible request instead of being resolved to something arbitrary.

Does zero sharps and zero flats mean C major?

For a major key, yes, since C major needs no alterations, and its relative minor is A minor, which shares the same notes. That is the case the tool reports as an open key, with no accidentals to list.

How do I tell a major key from its relative minor by the signature alone?

You cannot, because they are identical by definition. The signature narrows the key to a pair, and which of the two it is comes from the music itself, usually from which note the piece treats as home. The relative minor is always three semitones below the major tonic.

Key Signature Identifier

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Key Signature Identifier works in both directions: count the sharps or flats to find the key, or name a key to see its signature. It also gives the order the accidentals appear in.

What is Key Signature Identifier?

Choose a direction, then either pick how many sharps or flats the signature has or select a major key, and the answer appears with the relative minor.

The two directions:

A signature-to-key mode with two rows of buttons, one for zero to seven sharps and one for zero to seven flats.
A key-to-signature mode with a selector covering fifteen major keys, from C through the sharp keys to the flat ones.
A result naming the major key and its relative minor together.
A line listing the accidentals in the order they appear in the signature, or stating that the key is open when there are none.

The two directions are the same lookup read from either end. Counting sharps upward from none gives the keys in fifths: one sharp is G, two is D, three is A, and so on as far as seven. Counting flats gives the keys in fourths, since each added flat takes the key a fifth down: one flat is F, two is B flat, three is E flat. Seven of each is the practical limit, and the reason is that beyond seven the signature would have to double an accidental, which is why the keys at the far side of the wheel appear in their enharmonic equivalents instead. The order in which the accidentals appear is fixed and is worth knowing, because it is the same in every key. Sharps arrive as F sharp, C sharp, G sharp, D sharp, A sharp, E sharp and B sharp, and flats arrive as B flat, E flat, A flat, D flat, G flat, C flat and F flat; in both cases each new accidental is a fifth above or below the previous one. The result also gives the relative minor for every key, which shares the signature exactly. A signature cannot contain both kinds of accidental, and trying to select both is rejected rather than guessed at.

What it does not cover:

Major keys and their relative minors only, so the parallel minor keys are not listed.
No double sharps or double flats, since the seven-accidental limit is reached first.
Nothing about how a key signature is drawn on a stave.
No audio and no chord information.
Both accidentals at once is an error rather than a case to be resolved.
Nothing is uploaded, and no choice is remembered between visits.

Use it when reading a score rather than writing one, when a key has to be confirmed from its signature, or when the order the accidentals appear in needs checking before writing them out. When the wider relationship between keys is what matters, the circle of fifths tool places every key on the wheel, and when the chords within the identified key are needed, the chord progression builder lists them. The two directions are worth using together when reading a new piece: count the accidentals in the signature, take the pair of keys it identifies, and then decide from the music which of the two is the tonic. Nearly every confusion about key signatures comes from the fact that a signature names two keys rather than one.

How to use Key Signature Identifier

Choose whether you are starting from a signature or from a key.
Pick the number of sharps or flats, or select the major key.
Read the major key and its relative minor from the result.
Note the order of the accidentals if the signature is being written out.

When to use Key Signature Identifier vs related tools

Key Signature Identifier is the tool for translating between a key and its accidentals, in whichever direction the question comes. Circle of Fifths Tool shows the same information as a relationship between keys and adds the diatonic chords. When the key is known and the scale or the chords need spelling out, Scale Generator and Chord Progression Builder continue from there.

Privacy & Security

This tool runs entirely in your browser — no data ever leaves your device. There is no server round-trip, no upload, no logging, and no account required. Your input is processed locally using client-side JavaScript and is never stored, transmitted, or accessible to anyone else. When you close the tab, everything disappears.