Intervals in music
An interval is the distance between two notes, measured in half steps and named by how many letters it spans. C up to G is a perfect fifth (7 half steps); C up to E is a major third (4 half steps). There are 12 intervals within an octave. Tap each one to hear it.
Numbers: counting letter names
The number of an interval comes from the letters. Count from the bottom note to the top note and include both. C to D spans two letters, so it is a second. C to E spans three (C, D, E), so it is a third. C to G spans five, so it is a fifth. C up to the next C spans eight, which is why it is called an octave.
Letters decide the number even when sharps and flats are involved. C to E♭ is still a third, because it still spans C, D, E. C to D♯ sounds the same as C to E♭ on the piano, but it spans only two letters, so it is a second (an augmented second). That is why spelling matters in theory, even when it does not change the sound.
Qualities: counting half steps
The quality tells you the exact size. Count half steps (piano keys or guitar frets) between the two notes:
- Perfect: unisons, fourths, fifths and octaves. C to F is a perfect fourth (5 half steps), C to G a perfect fifth (7).
- Major and minor: seconds, thirds, sixths and sevenths. The minor version is one half step smaller. C to E is a major third (4); C to E♭ is a minor third (3).
- Augmented and diminished: one half step bigger than perfect or major, or one smaller than perfect or minor. C to F♯ is an augmented fourth; C to G♭ is a diminished fifth. Both are 6 half steps, the tritone.
A quick check for the major ones: every note of the major scale sits a major or perfect interval above its root. In C major that is D (M2), E (M3), F (P4), G (P5), A (M6), B (M7).
Consonance and dissonance
Some intervals sound settled and some sound tense. Octaves, fifths and unisons are the most stable, called perfect consonances. Thirds and sixths are sweet and full, called imperfect consonances; they are what make chords sound rich. Seconds, sevenths and the tritone are dissonant: they rub and want to move somewhere. The fourth sits in between; it sounds open on its own but tense over a bass note.
Dissonant does not mean bad. Tension is what gives music forward motion. A dominant seventh chord like G7 contains a tritone, and that tension is why it pulls so strongly back to C.
Inversions
Invert an interval by moving the bottom note up an octave. C up to E (a major third) becomes E up to C (a minor sixth). Two rules make inversions easy: the numbers always add up to 9 (third + sixth, second + seventh, fourth + fifth), and the half steps add up to 12. Major turns into minor and minor into major; perfect stays perfect; augmented turns into diminished.
Inversions explain why a fifth and a fourth feel related, and why chord inversions keep their identity. See triads and their inversions.
All 12 intervals from C
Melodic means one note after the other; harmonic means both at once. Open any interval for its page with every starting note, the staff, and guitar shapes.
| Interval | Short | Half steps | From C | Inverts to | Hear it |
|---|---|---|---|---|---|
| minor second | m2 | 1 | C–D♭ | major seventh | |
| major second | M2 | 2 | C–D | minor seventh | |
| minor third | m3 | 3 | C–E♭ | major sixth | |
| major third | M3 | 4 | C–E | minor sixth | |
| perfect fourth | P4 | 5 | C–F | perfect fifth | |
| tritone augmented fourth / diminished fifth | A4 | 6 | C–F♯ | tritone | |
| perfect fifth | P5 | 7 | C–G | perfect fourth | |
| minor sixth | m6 | 8 | C–A♭ | major third | |
| major sixth | M6 | 9 | C–A | minor third | |
| minor seventh | m7 | 10 | C–B♭ | major second | |
| major seventh | M7 | 11 | C–B | minor second | |
| octave | P8 | 12 | C–C | unison |
Intervals inside chords and scales
Chords are stacks of intervals. A major triad is a major third with a minor third on top: C, E, G in C major. A power chord is a root and a perfect fifth. Intervals larger than an octave are called compound: a ninth is an octave plus a second, which is where the D in C9 comes from.
Scales are strings of small intervals: the major scale is whole steps (major seconds) and half steps (minor seconds) in a fixed order. On guitar, most intervals have a fixed shape you can move anywhere on the neck; see guitar fretboard notes.
Ear training with intervals
- Pick two intervals that sound very different, such as the minor third and the perfect fifth.
- Tap each one melodically, then harmonically. Sing the top note back.
- Close your eyes, tap one at random, and name it. Check the label.
- When you get it right nine times out of ten, add one more interval.
- Practice going down as well as up; descending intervals sound different at first.
Related: music theory basics · scales · chords · circle of fifths
Interval questions
What is an interval in music?
The distance between two notes. It has a number (how many letter names it spans, counting both ends) and a quality (perfect, major, minor, augmented or diminished) that pins down the exact size in half steps.
How do you count intervals?
Count the letter names from the bottom note to the top note, including both. C to E is C, D, E: three letters, so a third. Then count half steps to get the quality: C to E is 4 half steps (a major third), C to E♭ is 3 (a minor third).
What are the perfect intervals?
The unison, the fourth, the fifth and the octave. They are called perfect because they have only one common size in the major scale and sound very stable. Seconds, thirds, sixths and sevenths come in major and minor sizes instead.
What is the tritone?
The interval of 6 half steps, exactly half an octave. From C it is F♯ (augmented fourth) or G♭ (diminished fifth). It is the most unstable interval and gives dominant seventh chords their pull. See the tritone page.
What is an interval inversion?
Flip the two notes so the bottom one goes up an octave. The numbers add up to 9 (a third becomes a sixth) and the half steps add up to 12. Major becomes minor, minor becomes major, and perfect stays perfect.
How can I learn to recognize intervals by ear?
Start with two contrasting pairs, like the major third and the perfect fifth. Play each one melodically (one note after the other) and harmonically (together), sing the top note, then have someone quiz you or use the buttons on this page with your eyes closed. Add one new interval at a time.
Every interval on this page is spelled and played by the site's theory engine. Updated September 2026.