Intervals in music: names, sizes and how to count them

An interval is the distance between two notes. Every melody is a string of intervals, and every chord is a stack of them. If you can name intervals, you can read music faster, build chords, understand scales and hear what is happening in a piece. Intervals are the vocabulary behind most of music theory.

Each interval has two parts to its name: a number and a quality. The number tells you how far apart the letters are. The quality tells you the exact size in half steps. This page explains both.

How do you find the number of an interval?

Count the letter names from the lower note to the upper note, including both ends. Ignore sharps and flats for this step. C to E is C, D, E, which is three letters, so it is a third. C to G is C, D, E, F, G, which is five letters, so it is a fifth. A note with itself is a unison, or first. Eight letters apart is an octave.

What is interval quality?

The number alone is not enough. C to E and C to E♭ are both thirds, but they sound different and have different sizes. Quality names the exact size. There are five qualities: perfect, major, minor, augmented and diminished.

Unisons, fourths, fifths and octaves can be perfect. Seconds, thirds, sixths and sevenths can be major or minor. Any interval can be made one half step bigger (augmented) or smaller (diminished) than its usual size. A minor interval is one half step smaller than the major one. An augmented interval is one half step larger than major or perfect. A diminished interval is one half step smaller than minor or perfect.

How many half steps is each interval?

Count half steps on a keyboard, where each key (black or white) is one half step. See half steps and whole steps if you want a refresher. The table shows every interval within one octave above C.

What do the intervals look like?

Read more about specific intervals on their own pages, such as the major third, perfect fifth, tritone and octave.

What are melodic and harmonic intervals?

When two notes sound one after the other, the interval is melodic. When they sound together, it is harmonic. The name of the interval is the same either way. Melodic intervals can go up or down. Going down by a fifth from C lands on F, not G.

What is an interval inversion?

Turn an interval upside down by moving the lower note up an octave. The result is its inversion. Two rules help: the numbers always add up to 9, and the qualities swap. A third becomes a sixth, a fourth becomes a fifth, a second becomes a seventh. Major becomes minor, minor becomes major, augmented becomes diminished, and perfect stays perfect.

Which intervals are consonant and which are dissonant?

Some intervals sound stable and smooth. These are consonant. Others sound tense and want to move. These are dissonant. Traditionally, the unison, octave and perfect fifth are perfect consonances. Thirds and sixths are imperfect consonances. Seconds, sevenths and the tritone are dissonances. The perfect fourth is treated as consonant in some situations and dissonant in others, which is a point theory teachers like to debate.

Dissonant does not mean bad. Dissonance gives music its motion and drama, and a dissonance resolving into a consonance feels like a deep breath out.

What are compound intervals?

Intervals larger than an octave are compound. A ninth is an octave plus a second. A tenth is an octave plus a third. Chords such as a ninth chord use these. To name one, subtract 7 from the number: a ninth is a second, a tenth is a third.

How can you practice intervals?

1. Pick a starting note and count the letter names to the second note to find the number.
2. Count half steps and check the table for the quality.
3. Play each one on a piano or sing it, so that you connect the name with the sound.
4. Link each interval to a song you know, such as the first two notes of a familiar tune.

The best way to learn intervals is to hear them. Try the note trainer for practice and the music theory quiz to test yourself.

Interval chart

Check yourself

Related pages

• Tritone: the interval of six half steps
• Octave: the interval of twelve half steps
• Half steps and whole steps (semitones and tones)
• Piano chords: how to build and play them
• Major scales: how they work in all 12 keys
• Note reading trainer