How Many Notes Are There in Music? Why Twelve
Western music uses 12 different notes. Seven of them have letter names, C, D, E, F, G, A and B, and the other five sit between them and are named as sharps or flats: C♯/D♭, D♯/E♭, F♯/G♭, G♯/A♭ and A♯/B♭. After the twelfth note the pattern starts again, one octave higher, which is why a piano’s 88 keys contain only 12 notes, repeated.
What are the 12 notes?
Starting from C and moving up one key at a time on a keyboard, white and black, the 12 notes are:
C, C♯, D, D♯, E, F, F♯, G, G♯, A, A♯, B
The next key is C again. Each step is a semitone, the smallest distance in Western music. The black keys are the five in-between notes, and each has two names: the black key between C and D is both C♯ (C raised) and D♭ (D lowered). The notes and semitones lesson shows how to find all twelve on a keyboard.
If there are 12 notes, why are there only 7 letters?
There are 7 letters because most music uses 7 notes at a time. A major or minor scale picks 7 of the 12 notes, one for each letter, and the letters were named around those scales. The white keys of the piano are exactly the C major scale. The other five notes are written as a letter with a sharp or a flat, so every scale still uses each letter once. The article Do Re Mi or C D E? covers the other naming systems, which name the same twelve notes.
Why do the notes repeat?
The notes repeat because of the octave. Two notes an octave apart have frequencies in the ratio 2:1, and the ear hears them as the same note at a different height. A man and a child singing the same tune an octave apart sound like they are singing the same notes. So music names one octave’s worth of notes and reuses the names higher and lower: C4 and C5 are both C.
How many notes are on a piano?
A standard piano has 88 keys, 52 white and 36 black, from A0 at the bottom to C8 at the top. That is just over seven octaves of the same 12 notes. A guitar works the same way: every fret is one semitone, so 12 frets up a string brings you back to the open string’s note, an octave higher.
Why twelve notes and not some other number?
Twelve is the smallest number of equal steps that gives a very good perfect fifth, the interval with the frequency ratio 3:2 that, after the octave, sounds the most stable.
Stack perfect fifths from C and you get C, G, D, A, E, B, F♯ and so on. Twelve fifths almost land back on C, seven octaves higher. They miss by a small amount, about a quarter of a semitone, so pure fifths never close the circle exactly. Modern tuning, equal temperament, solves that by splitting the octave into 12 exactly equal semitones and making every fifth a tiny bit narrow. The circle of fifths lesson follows that chain of fifths around all twelve keys.
The compromise is small where it matters most, and larger elsewhere. Musicians measure it in cents, hundredths of a semitone:
| Interval | Pure ratio | Pure size | Equal-tempered size | Difference |
|---|---|---|---|---|
| Octave | 2:1 | 1200 cents | 1200 cents | none |
| Perfect fifth | 3:2 | about 702 cents | 700 cents | about 2 cents |
| Major third | 5:4 | about 386 cents | 400 cents | about 14 cents |
Fewer equal steps cannot get the fifth that close. Dividing the octave into 5 or 7 equal steps puts the fifth more than 15 cents off, and no division into fewer than 29 equal steps gets a closer fifth than 12 does.
Where do 5-note and 7-note scales come from?
They come from the same chain of fifths, cut shorter. Five fifths in a row, C–G–D–A–E, give the notes of the pentatonic scale, C D E G A. Seven, F–C–G–D–A–E–B, give the seven notes of C major. Twelve give every note. That is why the pentatonic scale fits inside the major scale, and the major scale fits inside the twelve.
Do other musical traditions use 12 notes?
Not all of them. Twelve is the standard of Western music, and other traditions divide pitch differently:
- Arabic music works with maqamat, scales that include intervals between a semitone and a whole tone. Theory often describes them on a grid of 24 steps to the octave, called quarter tones, although the exact sizes vary by region and performer.
- Indian classical music names 22 shrutis, fine pitch positions, in its theory. In practice a performer works with 12 note positions, svaras, in the octave, and each raga chooses its notes from them, often with inflections between them.
- Javanese gamelan uses two tuning systems: slendro, with five notes to the octave, and pelog, with seven. Each gamelan set is tuned to itself, so its notes do not match a piano’s.
Composers and theorists have also tried splitting the octave into 19, 24, 31 or 53 equal steps. The ear can tell apart pitches much closer than a semitone, so twelve is a choice, not a limit of hearing.
Is a C sharp the same note as a D flat?
On a piano, yes: C♯ and D♭ are the same key and sound the same. They are written differently because they do different jobs in different keys: Sharp vs Flat shows how the key decides which name to write, and the enharmonic intervals lesson explains when the spelling matters.
Try it
The twelve notes become useful once you can find them without counting. The find the note exercise names a note and asks you to play it on your own instrument, keyboard, guitar or another, starting with the seven natural notes and then all twelve.