What an interval is
An interval is the distance between two notes. Its name has two parts: a number and a quality. This lesson is the number; the next one is the quality.
The number — count the letters, both ends included
From C up to E: say the letters — C, D, E — that's three letters, so it's a 3rd. From D up to A: D, E, F, G, A — five letters — a 5th. Always count the starting note as "1".
The number ignores sharps and flats. C→E and C→E♭ are both "some kind of 3rd" — the sharp only changes the quality.
On the staff there's a quick visual check: a 2nd is line-to-neighbouring-space; a 3rd is line-to-line or space-to-space (both noteheads on lines, or both in spaces); a 5th skips two.
Melodic or harmonic
The same interval can arrive two ways:
- melodically — one note then the other, as a leap in a tune;
- harmonically — both together, as a double stop or part of a chord.
On the violin, an interval is also a hand shape. A 3rd is two fingers close on adjacent strings; an octave is the wide 1st-and-4th-finger stretch across two strings. You'll feel common intervals long before you can name every one by ear.
Try it
Try
On the A string, play open A, then each finger in turn, naming the interval from A each time: A→B (1st finger) is a 2nd, A→C♯ (high 2) is a 3rd, A→D (3rd finger) is a 4th, A→E (4th finger, or the open E) is a 5th. Say the number out loud as you drop each finger.
Counting intervals
- 1
- 2
- 3
- 4
The usual mistake
Counting the gaps instead of the notes — saying C to D is a "1st" because you moved one step. Count the notes, and count the one you start on. C to D touches two letters, so it's a 2nd. C to C (same note) is a unison — a "1st".