In this guide
An interval describes the pitch distance between two notes. Count note names to find its number, then use the exact pitches to determine its quality. Notes played in succession form a melodic interval; notes played together form a harmonic interval.
For the specific 12-semitone interval, see what an octave is and how to find it.
An interval in music is the distance in pitch between two notes. For example, C to the next E above it is a major third; C to the next G above it is a perfect fifth. The notes can be played one after another or at the same time.
Interval names have two parts: a number, such as third or fifth, and a quality, such as major, minor or perfect. The Open University's interval lesson explains both parts and distinguishes melodic from harmonic intervals.
How to count an interval
- Count the note letters inclusively. From C to E, count C–D–E: that makes a third. From C to G, count C–D–E–F–G: that makes a fifth.
- Count the exact pitch distance. On a piano, each move to an adjacent key, including black keys, is one semitone (half step). C to E is four semitones; C to E♭ is three.
- Combine the number and quality. C–E is a major third, while C–E♭ is a minor third. They have the same number because both span the note letters C through E, but their exact pitch distances differ.
Count the letters and semitones separately: semitone count alone does not always determine the written name. In equal temperament, C–F♯ and C–G♭ use the same sounding keyboard keys but are written as an augmented fourth and a diminished fifth respectively. musictheory.net's interval-writing lesson illustrates this spelling distinction.
Common intervals from C
| Ascending notes | Interval | Semitones |
|---|---|---|
| C–D♭ | Minor second | 1 |
| C–D | Major second | 2 |
| C–E♭ | Minor third | 3 |
| C–E | Major third | 4 |
| C–F | Perfect fourth | 5 |
| C–G | Perfect fifth | 7 |
| C–C above | Octave | 12 |
These are ascending examples within one octave, not a list of every interval. An interval can also descend: E down to C spans a major third in the opposite direction. A unison describes the same pitch; an octave reaches the next note with the same letter name.
Melodic vs. harmonic intervals
Play C followed by E: you hear a melodic interval, because the notes occur in succession. Play C and E together: you hear a harmonic interval. The pitch relationship is still a major third; the distinction describes when the notes sound.
Intervals help describe melodic movement and harmony. A singer might move up a third between two notes, while two singers might sing a third apart. The exact performance and surrounding chords influence the sound; an interval name alone does not identify a whole chord or key.
Try a short listening exercise
- Play C and then E on a keyboard or another instrument. Count C–D–E and note that C–E spans four semitones.
- Play C and E♭. Both pairs are thirds, but the upper note is one semitone lower in the second pair. Compare their sounds.
- Play C and G, first separately and then together. Count the five letter names and seven semitones.
- Repeat starting on another pitch. For example, D–F♯ is also a major third: D–E–F is three letters and the pitches are four semitones apart.
You can build these distances from a scale, but an interval is the relationship between two notes rather than the whole scale. See what a scale in music is for major and minor note patterns.
Intervals and changing the pitch of audio
Musicians often describe transposition in semitones: raising all notes by two semitones moves each note up by a major second in pitch distance, though the written spelling depends on context. A whole recording may contain many notes and intervals; shifting the recording does not identify or isolate any particular one.
The audio pitch changer can shift a supported short local file by semitones while attempting to preserve tempo. Compare the actual output with the original: processing can change the sound. Check the tool's input and output limits and use audio you have permission to edit. For a musical key change, see how to change the key of a song.
Common questions
Is an interval always played upward?
No. Notes can move upward or downward, or sound together. Describe direction when it matters.
What is the smallest interval?
In the common twelve-note equal-tempered system, adjacent pitch classes are a semitone apart. Other tuning systems and musical traditions can use smaller pitch differences.
Are a third and a chord the same thing?
No. A third describes the relationship between two notes. A chord usually combines three or more notes, although terminology and musical context vary.