What Is a Scale?

Play the white keys from middle C up to the next C, one at a time: C, D, E, F, G, A, B, C. You have just played the C major scale.

Between those two Cs a keyboard has twelve different notes, black keys included. The scale uses seven of them and skips the other five. The eighth note is C again, an octave higher, which is why a scale is written from one note up to the same note and stops there. The Note System explains why the letters start over at that point.

A melody rarely needs all twelve. Twinkle, Twinkle, Little Star in C opens with C C G G A A G, F F E E D D C: six of the seven notes of C major, and not one black key.

Count the semitones from each note to the next, black keys included:

C to D is 2. D to E is 2. E to F is 1. F to G is 2. G to A is 2. A to B is 2. B to C is 1.

That gives the pattern 2 2 1 2 2 2 1. The two steps of 1 fall at E to F and B to C, the only two places on a keyboard where two white keys touch with no black key between them. Play the scale in the listening block and follow where those two short steps land.

The pattern is what makes a scale major. Start it on G and you get G, A, B, C, D, E, F sharp, G. The sixth step has to be a 2, and two semitones above E is the black key, F sharp. Start on D and the same pattern needs two black keys, F sharp and C sharp.

Every major scale has that one shape. The starting note decides which keys it lands on.

The natural minor scale has its own pattern: 2 1 2 2 1 2 2. Start it on C and you get C, D, E flat, F, G, A flat, B flat, C.

Play C major and then C minor from the same C. Four notes stay where they were: C, D, F and G. The other three each move down one semitone, so E becomes E flat, A becomes A flat and B becomes B flat.

The first of those is the note that turns a C major chord into C minor. On What Is a Chord? the E drops to E flat and the chord changes type; in the scale the third note does the same thing, and two more follow it down.

The Minor Scales covers harmonic and melodic minor, which raise some of those notes again.

Start the minor pattern on A: A, B, C, D, E, F, G, A. Every one of those is a white key. A minor and C major contain exactly the same seven notes.

Play the white keys from C up to C, then from A up to A. You press the same seven keys both times. What changes is the note the run starts on and returns to. Musicians call that note the tonic, or simply home.

So a set of notes on its own does not settle which scale you are hearing. Two songs can use identical notes and sit in different keys, because each one treats a different note as home. What a Key Is picks up from there, and Find the Tonic trains you to hear which note it is.

No. Take C major and leave out F and B, the two notes that sit one semitone above their neighbor. What remains is C, D, E, G, A: the major pentatonic scale, five notes with no two of them a semitone apart.

The five black keys form a pentatonic scale of their own. Play them in any order you like. No pair of them sits a semitone apart, so none of them rubs against another the way E and F do when you press them together.

Four scales from the same C, side by side:

Each pattern adds up to 12, because each one climbs exactly one octave. The pentatonic and blues scales build on the five-note version, and the modes use the major pattern starting from a different step of it.

Take the C major scale and stack every other note, starting on C: C, E, G. That is a C major chord. Start on D instead and you get D, F, A, which is D minor.

Do that on each of the seven notes and you get seven chords, one per step of the scale:

C, Dm, Em, F, G, Am, Bdim

Every note in those seven chords belongs to C major, so the melody and the harmony of a song in C are made from the same seven notes. Diatonic Chords has the same row for every key.

Start on F and go up a perfect fifth, seven semitones, six times in a row: F, C, G, D, A, E, B. Sort those seven into letter order starting from C and you have the C major scale.

Add one more fifth and you reach F sharp. Drop the F from the start of the chain and the seven notes are now G major. One note comes in and one goes out, which is why two neighboring keys share six of their seven notes. That chain is the idea behind the circle of fifths.

After the octave, the fifth is the simplest ratio two notes can have, 3 to 2. The Harmonic Series shows where that ratio comes from.