What Is an Interval
An interval is the distance between two notes. Not the notes themselves: the gap. This page is you measuring one, counting the keys yourself and pressing the one you land on, until the same count on a different starting note gives you the same answer.
- 2 measurements
- 13 inside an octave
- the unit of everything
read next
- Every interval
- The Note System
- What Is a Chord
- Consonance and Dissonance
An interval is a distance you can count.
Why does a third stay a third?
You counted seven keys up from C and landed on G. Then you counted seven up from F and landed on C. Different notes both times, and the card said perfect fifth both times.
That is what the number does: it counts letter names and nothing else. C up to E passes C, D and E, so it is a third. Put a flat on that E and it is still a third, because the letters did not move. The quality settles the rest, and four half steps is where it says major.
Go back up and count four from C, then three. One key, and you can hear which of the two you landed on.
The two measurements
- The number counts letter names
C up to E passes C, D and E, so it is a third. You count the note you start on as one. That is why the numbers always look one higher than you expect.
- The quality counts half steps
Four half steps makes that third major, three makes it minor. Same number, different size.
- A flat does not change the number
E flat is still a kind of E, so C to E flat is still some kind of third. The letter decides the number, the distance decides the quality.
- Perfect is used for four of them
The unison, fourth, fifth and octave have no major or minor version, because they come out the same whether you count up from the bottom note or down from the top.
Every distance inside one octave
Thirteen of them, measured from whichever note you start on. Pick a start note, click through, and the keyboard underneath shows you what you are hearing.
Where you run into this
- Two notes in a melody that keep the same distance when the song changes key
- A guitar capo, which moves every note and changes no interval
- A harmony vocal that sits a fixed distance above the lead
- Any chord at all, which is nothing but a stack of these distances
Keep going
Everything in sound and hearing
- The Note System
- What Is an Interval
- Tension and Expectation