Keys & Key Signatures
A key defines the tonal center of a piece of music — the note and scale that feel like "home." When a song is "in the key of G major," the melody and chords are drawn primarily from the G major scale. There are 24 commonly used keys: 12 major and 12 minor.
What "Being in a Key" Means
A key provides a framework for a piece of music. It tells you which notes are "in" (diatonic) and which are "out" (chromatic), which chords are expected and which are surprises. When a song is in C major, the note C feels like home, and the seven notes of the C major scale (C D E F G A B) form the primary palette.
Key Signatures
Each key has a key signature — a set of sharps or flats that define which notes are altered. C major has no sharps or flats. G major has one sharp (F#). Bb major has two flats (Bb, Eb). The pattern follows the circle of fifths: moving up a perfect 5th adds one sharp, moving down adds one flat.
| Key | Sharps/Flats |
|---|---|
| C major / A minor | None |
| G major / E minor | 1 sharp (F#) |
| D major / B minor | 2 sharps (F#, C#) |
| F major / D minor | 1 flat (Bb) |
| Bb major / G minor | 2 flats (Bb, Eb) |
Notice that each major key is paired with a relative minor that shares the same key signature. C major and A minor use the same seven notes, just centered on different tonics.
In ChordColor
Keys are available on /key/ pages (e.g., /key/g-major, /key/a-minor). Key pages display all 7 scale notes, 7 diatonic chords, related keys, and common progressions. The enharmonic display automatically selects sharps or flats based on the key's convention.