What are Intervals in Music Theory?

What do pop songs, piano concertos, and rock music all have in common? Music intervals!

Found in chords, melodies, and harmonies, intervals are the building blocks of music. You’d be hard pressed to find music that doesn’t contain a few intervals. Any time you have more than one note, there’s an interval between those notes. 

Intervals tell musicians the distance between notes. Another way to think of an interval is the difference in frequency of two tones. Understanding how intervals function can help improve sight reading, ear training, and music composition. Keep reading to learn how to identify intervals, how to find them on the piano, and what makes them so important in music theory. 

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What are intervals in music theory?

A music interval is the distance in pitch between two notes. In music theory, intervals can either be harmonic or melodic. Harmonic intervals are found in chords, when two notes are played at the same time. Melodic intervals can be found in a sequence of notes, when notes are played one at a time, as in a melody.

How do you count intervals in music?

To identify an interval, count the number of steps on the musical scale between the two notes. The same rule applies to identifying intervals on sheet music: count the number of lines and spaces between each note, including the lines/spaces the current notes are on. We’ll take a look at identifying intervals in A Major on the staff. From A to itself, the interval is called a unison, or first. 

To identify an interval, start by counting the first note of the interval as one. A is one and the second note B is two, so the interval from A up to B is a major second. Using this logic, let’s move up the scale.

A up to C# is a major third.

A up to D is a perfect fourth.

A up to E is a perfect fifth.

A up to F# is a major sixth.

A up to G# is a major seventh.

A up to A is a perfect eighth. Eighths are also known as octaves.

Intervals can start on any note of the scale. For example, there can be a third built on F (F-A) or a fifth built on G (G-D).

How many intervals are there in piano? What are the different types of musical intervals?

Intervals have both a numerical name (second, third, etc) as well as a quality. Qualities explain exactly the type of interval: major, minor, perfect, augmented, or diminished. Why does this matter? Well, for example, here are two intervals that have the same numerical name but have different qualities: C up to Eb and C up to E natural. Both are thirds, yet C up to Eb is a minor third, whereas C up to E natural is a major third. To differentiate the two, we need to understand major and minor intervals. 

 How to identify a major/minor interval:

• First, take the lower note of the interval and think of it as the tonic (the first note of the scale). For example, C is the tonic in the C major scale, D is the tonic in the D major scale, etc. 
• Then, determine if the upper note belongs to the major scale built on that tonic note. If it does, it creates either a major or perfect interval above the tonic note. 
• If the note is not in the scale, determine the quality of the interval. It is a minor interval if it is a half step smaller than a major interval, and it is called a diminished interval if it is a half step smaller than a perfect interval.

Here’s a general guide to understanding interval qualities:

• Only seconds, thirds, sixths, and sevenths can have a major or minor quality. 
• Perfect intervals are unisons, fourths, fifths, and octaves.
• Any size of interval can be augmented (made one half-step larger) or diminished (one half-step smaller). 

Returning back to the example, C up to E is a major third because E is in the C major scale. Major thirds have four half steps while minor thirds have three half steps. C up to Eb is a minor third because Eb does not occur in the major scale and the interval is a half step smaller than the major third. 

How do you find intervals on a piano?

The piano keyboard is a great way to understand music intervals because you can visually see the distance between each note. This isn’t always the case with a flute or a saxophone! We’ll use the C major scale to demonstrate intervals on the piano. 

C is a perfect unison interval (no half-steps). 

C up to D is a major second (2 half-steps). 

C up to E is a major third (four half-steps).

C up to F is a perfect fourth (5 half-steps).

C up to G is a perfect fifth (seven half-steps).

C up to A is a major sixth (nine half-steps).

C up to B is a major seventh (eleven half-steps).

C up to the next C is a perfect octave (12 half-steps).

Here are a few more examples of other kinds of intervals. C up to Eb is an example of a minor third. The top note is lowered one half-step from the major third. A up to G# is an example of an augmented seventh. The top note is raised one half-step from the major seventh. 

Why are intervals important in piano?

Intervals help musicians understand the structure of music. When you are able to recognize an interval by sight, it makes playing and sight reading so much easier. Recognizing intervals by ear can help musicians compose, or help them remember and play melodies without needing sheet music. 

If you’d like to develop your interval listening skills, free websites like Teoria and EarMaster have ear training exercises to develop interval recognition. 

Next time you’re listening to your favorite song, think about the music intervals you hear. Are the sounds close together? Far apart? With time and regular practice, identifying intervals will start to feel natural and you’ll find a difference in how you read, play, and interpret music.