Octave
An octave, also called a perfect octave or perfect eighth, is 12 half steps: from C up to C. The same note higher: the two blend so well they share a name, the upper one twice the frequency of the lower.
The octave at a glance
| Octave | |
|---|---|
| Half steps | 12 (six whole steps) |
| Letters it spans | 8: C D E F G A B C |
| Short name | P8 |
| Also called | a perfect octave or perfect eighth |
| Inverts to | A unison |
| Frequency ratio | 2 on a piano, 2:1 in just intonation |
Every note’s frequency in hertz is on the note frequency chart.
Songs that start with an octave
Going up: "Somewhere Over the Rainbow" ("Some-where").
Sing the tune’s first notes in your head and you have the interval from any starting note.
The octave in chords
Doubled in almost every chord: a pianist plays a chord’s root in both hands, an octave or two apart.
Every chord’s notes, to hear on a keyboard, are on piano chords.
An octave from every note
| From | Up an octave |
|---|---|
| C | C |
| C♯ | C♯ |
| D | D |
| E♭ | E♭ |
| E | E |
| F | F |
| F♯ | F♯ |
| G | G |
| A♭ | A♭ |
| A | A |
| B♭ | B♭ |
| B | B |
Questions about the octave
What is an octave in music?
An octave, also called a perfect octave or perfect eighth, is 12 half steps: from C up to C. The same note higher: the two blend so well they share a name, the upper one twice the frequency of the lower.
Why is it called an octave?
Because it is the eighth note of the scale: C D E F G A B C. Octo is Latin for eight.
What is the frequency of an octave?
Twice the lower note’s. A above middle C is 440 Hz, the A an octave up 880 Hz and the A an octave down 220 Hz.
What songs start with an octave?
"Somewhere Over the Rainbow" ("Some-where").
What is the inversion of an octave?
A unison: move the lower note up an octave and the two notes meet on the same pitch.
Other intervals
All of them side by side, with how to name one, are on the interval chart.
Put intervals in a song
Open the free editor with a beat playing, then draw a melody note by note in the piano roll and hear every leap. No account needed to start.
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